merge Benjamin's assertion-rewrite branch: all assertion related code is now part of py.test core distribution - the builtin assertion plugin to be precise.

See doc/assert.txt for details on how what has been improved.

CHANGELOG

@@ -1,6 +1,10 @@
-Changes between 2.0.3 and DEV
+Changes between 2.0.3 and 2.1.0.DEV
 ----------------------------------------------
 
+- merge Benjamin's assertionrewrite branch: now assertions
+  for test modules on python 2.6 and above are done by rewriting
+  the AST and saving the pyc file before the test module is imported.
+  see doc/assert.txt for more info.
 - fix issue43: improve doctests with better traceback reporting on
   unexpected exceptions
 - fix issue47: timing output in junitxml for test cases is now correct

_pytest/__init__.py

@@ -1,2 +1,2 @@
 #
-__version__ = '2.1.0.dev1'
+__version__ = '2.1.0.dev2'

_pytest/assertion/__init__.py

@@ -0,0 +1,128 @@
+"""
+support for presenting detailed information in failing assertions.
+"""
+import py
+import imp
+import marshal
+import struct
+import sys
+import pytest
+from _pytest.monkeypatch import monkeypatch
+from _pytest.assertion import reinterpret, util
+
+try:
+    from _pytest.assertion.rewrite import rewrite_asserts
+except ImportError:
+    rewrite_asserts = None
+else:
+    import ast
+
+def pytest_addoption(parser):
+    group = parser.getgroup("debugconfig")
+    group.addoption('--assertmode', action="store", dest="assertmode",
+                    choices=("on", "old", "off", "default"), default="default",
+                    metavar="on|old|off",
+                    help="""control assertion debugging tools.
+'off' performs no assertion debugging.
+'old' reinterprets the expressions in asserts to glean information.
+'on' (the default) rewrites the assert statements in test modules to provide
+sub-expression results.""")
+    group.addoption('--no-assert', action="store_true", default=False,
+        dest="noassert", help="DEPRECATED equivalent to --assertmode=off")
+    group.addoption('--nomagic', action="store_true", default=False,
+        dest="nomagic", help="DEPRECATED equivalent to --assertmode=off")
+
+class AssertionState:
+    """State for the assertion plugin."""
+
+    def __init__(self, config, mode):
+        self.mode = mode
+        self.trace = config.trace.root.get("assertion")
+
+def pytest_configure(config):
+    warn_about_missing_assertion()
+    mode = config.getvalue("assertmode")
+    if config.getvalue("noassert") or config.getvalue("nomagic"):
+        if mode not in ("off", "default"):
+            raise pytest.UsageError("assertion options conflict")
+        mode = "off"
+    elif mode == "default":
+        mode = "on"
+    if mode != "off":
+        def callbinrepr(op, left, right):
+            hook_result = config.hook.pytest_assertrepr_compare(
+                config=config, op=op, left=left, right=right)
+            for new_expl in hook_result:
+                if new_expl:
+                    return '\n~'.join(new_expl)
+        m = monkeypatch()
+        config._cleanup.append(m.undo)
+        m.setattr(py.builtin.builtins, 'AssertionError',
+                  reinterpret.AssertionError)
+        m.setattr(util, '_reprcompare', callbinrepr)
+    if mode == "on" and rewrite_asserts is None:
+        mode = "old"
+    config._assertstate = AssertionState(config, mode)
+    config._assertstate.trace("configured with mode set to %r" % (mode,))
+
+def _write_pyc(co, source_path):
+    if hasattr(imp, "cache_from_source"):
+        # Handle PEP 3147 pycs.
+        pyc = py.path(imp.cache_from_source(source_math))
+        pyc.dirname.ensure(dir=True)
+    else:
+        pyc = source_path + "c"
+    mtime = int(source_path.mtime())
+    fp = pyc.open("wb")
+    try:
+        fp.write(imp.get_magic())
+        fp.write(struct.pack("<l", mtime))
+        marshal.dump(co, fp)
+    finally:
+        fp.close()
+    return pyc
+
+def before_module_import(mod):
+    if mod.config._assertstate.mode != "on":
+        return
+    # Some deep magic: load the source, rewrite the asserts, and write a
+    # fake pyc, so that it'll be loaded when the module is imported.
+    source = mod.fspath.read()
+    try:
+        tree = ast.parse(source)
+    except SyntaxError:
+        # Let this pop up again in the real import.
+        mod.config._assertstate.trace("failed to parse: %r" % (mod.fspath,))
+        return
+    rewrite_asserts(tree)
+    try:
+        co = compile(tree, str(mod.fspath), "exec")
+    except SyntaxError:
+        # It's possible that this error is from some bug in the assertion
+        # rewriting, but I don't know of a fast way to tell.
+        mod.config._assertstate.trace("failed to compile: %r" % (mod.fspath,))
+        return
+    mod._pyc = _write_pyc(co, mod.fspath)
+    mod.config._assertstate.trace("wrote pyc: %r" % (mod._pyc,))
+
+def after_module_import(mod):
+    if not hasattr(mod, "_pyc"):
+        return
+    state = mod.config._assertstate
+    try:
+        mod._pyc.remove()
+    except py.error.ENOENT:
+        state.trace("couldn't find pyc: %r" % (mod._pyc,))
+    else:
+        state.trace("removed pyc: %r" % (mod._pyc,))
+
+def warn_about_missing_assertion():
+    try:
+        assert False
+    except AssertionError:
+        pass
+    else:
+        sys.stderr.write("WARNING: failing tests may report as passing because "
+        "assertions are turned off!  (are you using python -O?)\n")
+
+pytest_assertrepr_compare = util.assertrepr_compare

_pytest/assertion/newinterpret.py

@@ -0,0 +1,339 @@
+"""
+Find intermediate evalutation results in assert statements through builtin AST.
+This should replace oldinterpret.py eventually.
+"""
+
+import sys
+import ast
+
+import py
+from _pytest.assertion import util
+from _pytest.assertion.reinterpret import BuiltinAssertionError
+
+
+if sys.platform.startswith("java") and sys.version_info < (2, 5, 2):
+    # See http://bugs.jython.org/issue1497
+    _exprs = ("BoolOp", "BinOp", "UnaryOp", "Lambda", "IfExp", "Dict",
+              "ListComp", "GeneratorExp", "Yield", "Compare", "Call",
+              "Repr", "Num", "Str", "Attribute", "Subscript", "Name",
+              "List", "Tuple")
+    _stmts = ("FunctionDef", "ClassDef", "Return", "Delete", "Assign",
+              "AugAssign", "Print", "For", "While", "If", "With", "Raise",
+              "TryExcept", "TryFinally", "Assert", "Import", "ImportFrom",
+              "Exec", "Global", "Expr", "Pass", "Break", "Continue")
+    _expr_nodes = set(getattr(ast, name) for name in _exprs)
+    _stmt_nodes = set(getattr(ast, name) for name in _stmts)
+    def _is_ast_expr(node):
+        return node.__class__ in _expr_nodes
+    def _is_ast_stmt(node):
+        return node.__class__ in _stmt_nodes
+else:
+    def _is_ast_expr(node):
+        return isinstance(node, ast.expr)
+    def _is_ast_stmt(node):
+        return isinstance(node, ast.stmt)
+
+
+class Failure(Exception):
+    """Error found while interpreting AST."""
+
+    def __init__(self, explanation=""):
+        self.cause = sys.exc_info()
+        self.explanation = explanation
+
+
+def interpret(source, frame, should_fail=False):
+    mod = ast.parse(source)
+    visitor = DebugInterpreter(frame)
+    try:
+        visitor.visit(mod)
+    except Failure:
+        failure = sys.exc_info()[1]
+        return getfailure(failure)
+    if should_fail:
+        return ("(assertion failed, but when it was re-run for "
+                "printing intermediate values, it did not fail.  Suggestions: "
+                "compute assert expression before the assert or use --no-assert)")
+
+def run(offending_line, frame=None):
+    if frame is None:
+        frame = py.code.Frame(sys._getframe(1))
+    return interpret(offending_line, frame)
+
+def getfailure(failure):
+    explanation = util.format_explanation(failure.explanation)
+    value = failure.cause[1]
+    if str(value):
+        lines = explanation.splitlines()
+        if not lines:
+            lines.append("")
+        lines[0] += " << %s" % (value,)
+        explanation = "\n".join(lines)
+    text = "%s: %s" % (failure.cause[0].__name__, explanation)
+    if text.startswith("AssertionError: assert "):
+        text = text[16:]
+    return text
+
+
+operator_map = {
+    ast.BitOr : "|",
+    ast.BitXor : "^",
+    ast.BitAnd : "&",
+    ast.LShift : "<<",
+    ast.RShift : ">>",
+    ast.Add : "+",
+    ast.Sub : "-",
+    ast.Mult : "*",
+    ast.Div : "/",
+    ast.FloorDiv : "//",
+    ast.Mod : "%",
+    ast.Eq : "==",
+    ast.NotEq : "!=",
+    ast.Lt : "<",
+    ast.LtE : "<=",
+    ast.Gt : ">",
+    ast.GtE : ">=",
+    ast.Pow : "**",
+    ast.Is : "is",
+    ast.IsNot : "is not",
+    ast.In : "in",
+    ast.NotIn : "not in"
+}
+
+unary_map = {
+    ast.Not : "not %s",
+    ast.Invert : "~%s",
+    ast.USub : "-%s",
+    ast.UAdd : "+%s"
+}
+
+
+class DebugInterpreter(ast.NodeVisitor):
+    """Interpret AST nodes to gleam useful debugging information. """
+
+    def __init__(self, frame):
+        self.frame = frame
+
+    def generic_visit(self, node):
+        # Fallback when we don't have a special implementation.
+        if _is_ast_expr(node):
+            mod = ast.Expression(node)
+            co = self._compile(mod)
+            try:
+                result = self.frame.eval(co)
+            except Exception:
+                raise Failure()
+            explanation = self.frame.repr(result)
+            return explanation, result
+        elif _is_ast_stmt(node):
+            mod = ast.Module([node])
+            co = self._compile(mod, "exec")
+            try:
+                self.frame.exec_(co)
+            except Exception:
+                raise Failure()
+            return None, None
+        else:
+            raise AssertionError("can't handle %s" %(node,))
+
+    def _compile(self, source, mode="eval"):
+        return compile(source, "<assertion interpretation>", mode)
+
+    def visit_Expr(self, expr):
+        return self.visit(expr.value)
+
+    def visit_Module(self, mod):
+        for stmt in mod.body:
+            self.visit(stmt)
+
+    def visit_Name(self, name):
+        explanation, result = self.generic_visit(name)
+        # See if the name is local.
+        source = "%r in locals() is not globals()" % (name.id,)
+        co = self._compile(source)
+        try:
+            local = self.frame.eval(co)
+        except Exception:
+            # have to assume it isn't
+            local = False
+        if not local:
+            return name.id, result
+        return explanation, result
+
+    def visit_Compare(self, comp):
+        left = comp.left
+        left_explanation, left_result = self.visit(left)
+        for op, next_op in zip(comp.ops, comp.comparators):
+            next_explanation, next_result = self.visit(next_op)
+            op_symbol = operator_map[op.__class__]
+            explanation = "%s %s %s" % (left_explanation, op_symbol,
+                                        next_explanation)
+            source = "__exprinfo_left %s __exprinfo_right" % (op_symbol,)
+            co = self._compile(source)
+            try:
+                result = self.frame.eval(co, __exprinfo_left=left_result,
+                                         __exprinfo_right=next_result)
+            except Exception:
+                raise Failure(explanation)
+            try:
+                if not result:
+                    break
+            except KeyboardInterrupt:
+                raise
+            except:
+                break
+            left_explanation, left_result = next_explanation, next_result
+
+        if util._reprcompare is not None:
+            res = util._reprcompare(op_symbol, left_result, next_result)
+            if res:
+                explanation = res
+        return explanation, result
+
+    def visit_BoolOp(self, boolop):
+        is_or = isinstance(boolop.op, ast.Or)
+        explanations = []
+        for operand in boolop.values:
+            explanation, result = self.visit(operand)
+            explanations.append(explanation)
+            if result == is_or:
+                break
+        name = is_or and " or " or " and "
+        explanation = "(" + name.join(explanations) + ")"
+        return explanation, result
+
+    def visit_UnaryOp(self, unary):
+        pattern = unary_map[unary.op.__class__]
+        operand_explanation, operand_result = self.visit(unary.operand)
+        explanation = pattern % (operand_explanation,)
+        co = self._compile(pattern % ("__exprinfo_expr",))
+        try:
+            result = self.frame.eval(co, __exprinfo_expr=operand_result)
+        except Exception:
+            raise Failure(explanation)
+        return explanation, result
+
+    def visit_BinOp(self, binop):
+        left_explanation, left_result = self.visit(binop.left)
+        right_explanation, right_result = self.visit(binop.right)
+        symbol = operator_map[binop.op.__class__]
+        explanation = "(%s %s %s)" % (left_explanation, symbol,
+                                      right_explanation)
+        source = "__exprinfo_left %s __exprinfo_right" % (symbol,)
+        co = self._compile(source)
+        try:
+            result = self.frame.eval(co, __exprinfo_left=left_result,
+                                     __exprinfo_right=right_result)
+        except Exception:
+            raise Failure(explanation)
+        return explanation, result
+
+    def visit_Call(self, call):
+        func_explanation, func = self.visit(call.func)
+        arg_explanations = []
+        ns = {"__exprinfo_func" : func}
+        arguments = []
+        for arg in call.args:
+            arg_explanation, arg_result = self.visit(arg)
+            arg_name = "__exprinfo_%s" % (len(ns),)
+            ns[arg_name] = arg_result
+            arguments.append(arg_name)
+            arg_explanations.append(arg_explanation)
+        for keyword in call.keywords:
+            arg_explanation, arg_result = self.visit(keyword.value)
+            arg_name = "__exprinfo_%s" % (len(ns),)
+            ns[arg_name] = arg_result
+            keyword_source = "%s=%%s" % (keyword.arg)
+            arguments.append(keyword_source % (arg_name,))
+            arg_explanations.append(keyword_source % (arg_explanation,))
+        if call.starargs:
+            arg_explanation, arg_result = self.visit(call.starargs)
+            arg_name = "__exprinfo_star"
+            ns[arg_name] = arg_result
+            arguments.append("*%s" % (arg_name,))
+            arg_explanations.append("*%s" % (arg_explanation,))
+        if call.kwargs:
+            arg_explanation, arg_result = self.visit(call.kwargs)
+            arg_name = "__exprinfo_kwds"
+            ns[arg_name] = arg_result
+            arguments.append("**%s" % (arg_name,))
+            arg_explanations.append("**%s" % (arg_explanation,))
+        args_explained = ", ".join(arg_explanations)
+        explanation = "%s(%s)" % (func_explanation, args_explained)
+        args = ", ".join(arguments)
+        source = "__exprinfo_func(%s)" % (args,)
+        co = self._compile(source)
+        try:
+            result = self.frame.eval(co, **ns)
+        except Exception:
+            raise Failure(explanation)
+        pattern = "%s\n{%s = %s\n}"
+        rep = self.frame.repr(result)
+        explanation = pattern % (rep, rep, explanation)
+        return explanation, result
+
+    def _is_builtin_name(self, name):
+        pattern = "%r not in globals() and %r not in locals()"
+        source = pattern % (name.id, name.id)
+        co = self._compile(source)
+        try:
+            return self.frame.eval(co)
+        except Exception:
+            return False
+
+    def visit_Attribute(self, attr):
+        if not isinstance(attr.ctx, ast.Load):
+            return self.generic_visit(attr)
+        source_explanation, source_result = self.visit(attr.value)
+        explanation = "%s.%s" % (source_explanation, attr.attr)
+        source = "__exprinfo_expr.%s" % (attr.attr,)
+        co = self._compile(source)
+        try:
+            result = self.frame.eval(co, __exprinfo_expr=source_result)
+        except Exception:
+            raise Failure(explanation)
+        explanation = "%s\n{%s = %s.%s\n}" % (self.frame.repr(result),
+                                              self.frame.repr(result),
+                                              source_explanation, attr.attr)
+        # Check if the attr is from an instance.
+        source = "%r in getattr(__exprinfo_expr, '__dict__', {})"
+        source = source % (attr.attr,)
+        co = self._compile(source)
+        try:
+            from_instance = self.frame.eval(co, __exprinfo_expr=source_result)
+        except Exception:
+            from_instance = True
+        if from_instance:
+            rep = self.frame.repr(result)
+            pattern = "%s\n{%s = %s\n}"
+            explanation = pattern % (rep, rep, explanation)
+        return explanation, result
+
+    def visit_Assert(self, assrt):
+        test_explanation, test_result = self.visit(assrt.test)
+        if test_explanation.startswith("False\n{False =") and \
+                test_explanation.endswith("\n"):
+            test_explanation = test_explanation[15:-2]
+        explanation = "assert %s" % (test_explanation,)
+        if not test_result:
+            try:
+                raise BuiltinAssertionError
+            except Exception:
+                raise Failure(explanation)
+        return explanation, test_result
+
+    def visit_Assign(self, assign):
+        value_explanation, value_result = self.visit(assign.value)
+        explanation = "... = %s" % (value_explanation,)
+        name = ast.Name("__exprinfo_expr", ast.Load(),
+                        lineno=assign.value.lineno,
+                        col_offset=assign.value.col_offset)
+        new_assign = ast.Assign(assign.targets, name, lineno=assign.lineno,
+                                col_offset=assign.col_offset)
+        mod = ast.Module([new_assign])
+        co = self._compile(mod, "exec")
+        try:
+            self.frame.exec_(co, __exprinfo_expr=value_result)
+        except Exception:
+            raise Failure(explanation)
+        return explanation, value_result

_pytest/assertion/oldinterpret.py

@@ -0,0 +1,556 @@
+import py
+import sys, inspect
+from compiler import parse, ast, pycodegen
+from _pytest.assertion.util import format_explanation
+from _pytest.assertion.reinterpret import BuiltinAssertionError
+
+passthroughex = py.builtin._sysex
+
+class Failure:
+    def __init__(self, node):
+        self.exc, self.value, self.tb = sys.exc_info()
+        self.node = node
+
+class View(object):
+    """View base class.
+
+    If C is a subclass of View, then C(x) creates a proxy object around
+    the object x.  The actual class of the proxy is not C in general,
+    but a *subclass* of C determined by the rules below.  To avoid confusion
+    we call view class the class of the proxy (a subclass of C, so of View)
+    and object class the class of x.
+
+    Attributes and methods not found in the proxy are automatically read on x.
+    Other operations like setting attributes are performed on the proxy, as
+    determined by its view class.  The object x is available from the proxy
+    as its __obj__ attribute.
+
+    The view class selection is determined by the __view__ tuples and the
+    optional __viewkey__ method.  By default, the selected view class is the
+    most specific subclass of C whose __view__ mentions the class of x.
+    If no such subclass is found, the search proceeds with the parent
+    object classes.  For example, C(True) will first look for a subclass
+    of C with __view__ = (..., bool, ...) and only if it doesn't find any
+    look for one with __view__ = (..., int, ...), and then ..., object,...
+    If everything fails the class C itself is considered to be the default.
+
+    Alternatively, the view class selection can be driven by another aspect
+    of the object x, instead of the class of x, by overriding __viewkey__.
+    See last example at the end of this module.
+    """
+
+    _viewcache = {}
+    __view__ = ()
+
+    def __new__(rootclass, obj, *args, **kwds):
+        self = object.__new__(rootclass)
+        self.__obj__ = obj
+        self.__rootclass__ = rootclass
+        key = self.__viewkey__()
+        try:
+            self.__class__ = self._viewcache[key]
+        except KeyError:
+            self.__class__ = self._selectsubclass(key)
+        return self
+
+    def __getattr__(self, attr):
+        # attributes not found in the normal hierarchy rooted on View
+        # are looked up in the object's real class
+        return getattr(self.__obj__, attr)
+
+    def __viewkey__(self):
+        return self.__obj__.__class__
+
+    def __matchkey__(self, key, subclasses):
+        if inspect.isclass(key):
+            keys = inspect.getmro(key)
+        else:
+            keys = [key]
+        for key in keys:
+            result = [C for C in subclasses if key in C.__view__]
+            if result:
+                return result
+        return []
+
+    def _selectsubclass(self, key):
+        subclasses = list(enumsubclasses(self.__rootclass__))
+        for C in subclasses:
+            if not isinstance(C.__view__, tuple):
+                C.__view__ = (C.__view__,)
+        choices = self.__matchkey__(key, subclasses)
+        if not choices:
+            return self.__rootclass__
+        elif len(choices) == 1:
+            return choices[0]
+        else:
+            # combine the multiple choices
+            return type('?', tuple(choices), {})
+
+    def __repr__(self):
+        return '%s(%r)' % (self.__rootclass__.__name__, self.__obj__)
+
+
+def enumsubclasses(cls):
+    for subcls in cls.__subclasses__():
+        for subsubclass in enumsubclasses(subcls):
+            yield subsubclass
+    yield cls
+
+
+class Interpretable(View):
+    """A parse tree node with a few extra methods."""
+    explanation = None
+
+    def is_builtin(self, frame):
+        return False
+
+    def eval(self, frame):
+        # fall-back for unknown expression nodes
+        try:
+            expr = ast.Expression(self.__obj__)
+            expr.filename = '<eval>'
+            self.__obj__.filename = '<eval>'
+            co = pycodegen.ExpressionCodeGenerator(expr).getCode()
+            result = frame.eval(co)
+        except passthroughex:
+            raise
+        except:
+            raise Failure(self)
+        self.result = result
+        self.explanation = self.explanation or frame.repr(self.result)
+
+    def run(self, frame):
+        # fall-back for unknown statement nodes
+        try:
+            expr = ast.Module(None, ast.Stmt([self.__obj__]))
+            expr.filename = '<run>'
+            co = pycodegen.ModuleCodeGenerator(expr).getCode()
+            frame.exec_(co)
+        except passthroughex:
+            raise
+        except:
+            raise Failure(self)
+
+    def nice_explanation(self):
+        return format_explanation(self.explanation)
+
+
+class Name(Interpretable):
+    __view__ = ast.Name
+
+    def is_local(self, frame):
+        source = '%r in locals() is not globals()' % self.name
+        try:
+            return frame.is_true(frame.eval(source))
+        except passthroughex:
+            raise
+        except:
+            return False
+
+    def is_global(self, frame):
+        source = '%r in globals()' % self.name
+        try:
+            return frame.is_true(frame.eval(source))
+        except passthroughex:
+            raise
+        except:
+            return False
+
+    def is_builtin(self, frame):
+        source = '%r not in locals() and %r not in globals()' % (
+            self.name, self.name)
+        try:
+            return frame.is_true(frame.eval(source))
+        except passthroughex:
+            raise
+        except:
+            return False
+
+    def eval(self, frame):
+        super(Name, self).eval(frame)
+        if not self.is_local(frame):
+            self.explanation = self.name
+
+class Compare(Interpretable):
+    __view__ = ast.Compare
+
+    def eval(self, frame):
+        expr = Interpretable(self.expr)
+        expr.eval(frame)
+        for operation, expr2 in self.ops:
+            if hasattr(self, 'result'):
+                # shortcutting in chained expressions
+                if not frame.is_true(self.result):
+                    break
+            expr2 = Interpretable(expr2)
+            expr2.eval(frame)
+            self.explanation = "%s %s %s" % (
+                expr.explanation, operation, expr2.explanation)
+            source = "__exprinfo_left %s __exprinfo_right" % operation
+            try:
+                self.result = frame.eval(source,
+                                         __exprinfo_left=expr.result,
+                                         __exprinfo_right=expr2.result)
+            except passthroughex:
+                raise
+            except:
+                raise Failure(self)
+            expr = expr2
+
+class And(Interpretable):
+    __view__ = ast.And
+
+    def eval(self, frame):
+        explanations = []
+        for expr in self.nodes:
+            expr = Interpretable(expr)
+            expr.eval(frame)
+            explanations.append(expr.explanation)
+            self.result = expr.result
+            if not frame.is_true(expr.result):
+                break
+        self.explanation = '(' + ' and '.join(explanations) + ')'
+
+class Or(Interpretable):
+    __view__ = ast.Or
+
+    def eval(self, frame):
+        explanations = []
+        for expr in self.nodes:
+            expr = Interpretable(expr)
+            expr.eval(frame)
+            explanations.append(expr.explanation)
+            self.result = expr.result
+            if frame.is_true(expr.result):
+                break
+        self.explanation = '(' + ' or '.join(explanations) + ')'
+
+
+# == Unary operations ==
+keepalive = []
+for astclass, astpattern in {
+    ast.Not    : 'not __exprinfo_expr',
+    ast.Invert : '(~__exprinfo_expr)',
+    }.items():
+
+    class UnaryArith(Interpretable):
+        __view__ = astclass
+
+        def eval(self, frame, astpattern=astpattern):
+            expr = Interpretable(self.expr)
+            expr.eval(frame)
+            self.explanation = astpattern.replace('__exprinfo_expr',
+                                                  expr.explanation)
+            try:
+                self.result = frame.eval(astpattern,
+                                         __exprinfo_expr=expr.result)
+            except passthroughex:
+                raise
+            except:
+                raise Failure(self)
+
+    keepalive.append(UnaryArith)
+
+# == Binary operations ==
+for astclass, astpattern in {
+    ast.Add    : '(__exprinfo_left + __exprinfo_right)',
+    ast.Sub    : '(__exprinfo_left - __exprinfo_right)',
+    ast.Mul    : '(__exprinfo_left * __exprinfo_right)',
+    ast.Div    : '(__exprinfo_left / __exprinfo_right)',
+    ast.Mod    : '(__exprinfo_left % __exprinfo_right)',
+    ast.Power  : '(__exprinfo_left ** __exprinfo_right)',
+    }.items():
+
+    class BinaryArith(Interpretable):
+        __view__ = astclass
+
+        def eval(self, frame, astpattern=astpattern):
+            left = Interpretable(self.left)
+            left.eval(frame)
+            right = Interpretable(self.right)
+            right.eval(frame)
+            self.explanation = (astpattern
+                                .replace('__exprinfo_left',  left .explanation)
+                                .replace('__exprinfo_right', right.explanation))
+            try:
+                self.result = frame.eval(astpattern,
+                                         __exprinfo_left=left.result,
+                                         __exprinfo_right=right.result)
+            except passthroughex:
+                raise
+            except:
+                raise Failure(self)
+
+    keepalive.append(BinaryArith)
+
+
+class CallFunc(Interpretable):
+    __view__ = ast.CallFunc
+
+    def is_bool(self, frame):
+        source = 'isinstance(__exprinfo_value, bool)'
+        try:
+            return frame.is_true(frame.eval(source,
+                                            __exprinfo_value=self.result))
+        except passthroughex:
+            raise
+        except:
+            return False
+
+    def eval(self, frame):
+        node = Interpretable(self.node)
+        node.eval(frame)
+        explanations = []
+        vars = {'__exprinfo_fn': node.result}
+        source = '__exprinfo_fn('
+        for a in self.args:
+            if isinstance(a, ast.Keyword):
+                keyword = a.name
+                a = a.expr
+            else:
+                keyword = None
+            a = Interpretable(a)
+            a.eval(frame)
+            argname = '__exprinfo_%d' % len(vars)
+            vars[argname] = a.result
+            if keyword is None:
+                source += argname + ','
+                explanations.append(a.explanation)
+            else:
+                source += '%s=%s,' % (keyword, argname)
+                explanations.append('%s=%s' % (keyword, a.explanation))
+        if self.star_args:
+            star_args = Interpretable(self.star_args)
+            star_args.eval(frame)
+            argname = '__exprinfo_star'
+            vars[argname] = star_args.result
+            source += '*' + argname + ','
+            explanations.append('*' + star_args.explanation)
+        if self.dstar_args:
+            dstar_args = Interpretable(self.dstar_args)
+            dstar_args.eval(frame)
+            argname = '__exprinfo_kwds'
+            vars[argname] = dstar_args.result
+            source += '**' + argname + ','
+            explanations.append('**' + dstar_args.explanation)
+        self.explanation = "%s(%s)" % (
+            node.explanation, ', '.join(explanations))
+        if source.endswith(','):
+            source = source[:-1]
+        source += ')'
+        try:
+            self.result = frame.eval(source, **vars)
+        except passthroughex:
+            raise
+        except:
+            raise Failure(self)
+        if not node.is_builtin(frame) or not self.is_bool(frame):
+            r = frame.repr(self.result)
+            self.explanation = '%s\n{%s = %s\n}' % (r, r, self.explanation)
+
+class Getattr(Interpretable):
+    __view__ = ast.Getattr
+
+    def eval(self, frame):
+        expr = Interpretable(self.expr)
+        expr.eval(frame)
+        source = '__exprinfo_expr.%s' % self.attrname
+        try:
+            self.result = frame.eval(source, __exprinfo_expr=expr.result)
+        except passthroughex:
+            raise
+        except:
+            raise Failure(self)
+        self.explanation = '%s.%s' % (expr.explanation, self.attrname)
+        # if the attribute comes from the instance, its value is interesting
+        source = ('hasattr(__exprinfo_expr, "__dict__") and '
+                  '%r in __exprinfo_expr.__dict__' % self.attrname)
+        try:
+            from_instance = frame.is_true(
+                frame.eval(source, __exprinfo_expr=expr.result))
+        except passthroughex:
+            raise
+        except:
+            from_instance = True
+        if from_instance:
+            r = frame.repr(self.result)
+            self.explanation = '%s\n{%s = %s\n}' % (r, r, self.explanation)
+
+# == Re-interpretation of full statements ==
+
+class Assert(Interpretable):
+    __view__ = ast.Assert
+
+    def run(self, frame):
+        test = Interpretable(self.test)
+        test.eval(frame)
+        # simplify 'assert False where False = ...'
+        if (test.explanation.startswith('False\n{False = ') and
+            test.explanation.endswith('\n}')):
+            test.explanation = test.explanation[15:-2]
+        # print the result as  'assert <explanation>'
+        self.result = test.result
+        self.explanation = 'assert ' + test.explanation
+        if not frame.is_true(test.result):
+            try:
+                raise BuiltinAssertionError
+            except passthroughex:
+                raise
+            except:
+                raise Failure(self)
+
+class Assign(Interpretable):
+    __view__ = ast.Assign
+
+    def run(self, frame):
+        expr = Interpretable(self.expr)
+        expr.eval(frame)
+        self.result = expr.result
+        self.explanation = '... = ' + expr.explanation
+        # fall-back-run the rest of the assignment
+        ass = ast.Assign(self.nodes, ast.Name('__exprinfo_expr'))
+        mod = ast.Module(None, ast.Stmt([ass]))
+        mod.filename = '<run>'
+        co = pycodegen.ModuleCodeGenerator(mod).getCode()
+        try:
+            frame.exec_(co, __exprinfo_expr=expr.result)
+        except passthroughex:
+            raise
+        except:
+            raise Failure(self)
+
+class Discard(Interpretable):
+    __view__ = ast.Discard
+
+    def run(self, frame):
+        expr = Interpretable(self.expr)
+        expr.eval(frame)
+        self.result = expr.result
+        self.explanation = expr.explanation
+
+class Stmt(Interpretable):
+    __view__ = ast.Stmt
+
+    def run(self, frame):
+        for stmt in self.nodes:
+            stmt = Interpretable(stmt)
+            stmt.run(frame)
+
+
+def report_failure(e):
+    explanation = e.node.nice_explanation()
+    if explanation:
+        explanation = ", in: " + explanation
+    else:
+        explanation = ""
+    sys.stdout.write("%s: %s%s\n" % (e.exc.__name__, e.value, explanation))
+
+def check(s, frame=None):
+    if frame is None:
+        frame = sys._getframe(1)
+        frame = py.code.Frame(frame)
+    expr = parse(s, 'eval')
+    assert isinstance(expr, ast.Expression)
+    node = Interpretable(expr.node)
+    try:
+        node.eval(frame)
+    except passthroughex:
+        raise
+    except Failure:
+        e = sys.exc_info()[1]
+        report_failure(e)
+    else:
+        if not frame.is_true(node.result):
+            sys.stderr.write("assertion failed: %s\n" % node.nice_explanation())
+
+
+###########################################################
+# API / Entry points
+# #########################################################
+
+def interpret(source, frame, should_fail=False):
+    module = Interpretable(parse(source, 'exec').node)
+    #print "got module", module
+    if isinstance(frame, py.std.types.FrameType):
+        frame = py.code.Frame(frame)
+    try:
+        module.run(frame)
+    except Failure:
+        e = sys.exc_info()[1]
+        return getfailure(e)
+    except passthroughex:
+        raise
+    except:
+        import traceback
+        traceback.print_exc()
+    if should_fail:
+        return ("(assertion failed, but when it was re-run for "
+                "printing intermediate values, it did not fail.  Suggestions: "
+                "compute assert expression before the assert or use --nomagic)")
+    else:
+        return None
+
+def getmsg(excinfo):
+    if isinstance(excinfo, tuple):
+        excinfo = py.code.ExceptionInfo(excinfo)
+    #frame, line = gettbline(tb)
+    #frame = py.code.Frame(frame)
+    #return interpret(line, frame)
+
+    tb = excinfo.traceback[-1]
+    source = str(tb.statement).strip()
+    x = interpret(source, tb.frame, should_fail=True)
+    if not isinstance(x, str):
+        raise TypeError("interpret returned non-string %r" % (x,))
+    return x
+
+def getfailure(e):
+    explanation = e.node.nice_explanation()
+    if str(e.value):
+        lines = explanation.split('\n')
+        lines[0] += "  << %s" % (e.value,)
+        explanation = '\n'.join(lines)
+    text = "%s: %s" % (e.exc.__name__, explanation)
+    if text.startswith('AssertionError: assert '):
+        text = text[16:]
+    return text
+
+def run(s, frame=None):
+    if frame is None:
+        frame = sys._getframe(1)
+        frame = py.code.Frame(frame)
+    module = Interpretable(parse(s, 'exec').node)
+    try:
+        module.run(frame)
+    except Failure:
+        e = sys.exc_info()[1]
+        report_failure(e)
+
+
+if __name__ == '__main__':
+    # example:
+    def f():
+        return 5
+    def g():
+        return 3
+    def h(x):
+        return 'never'
+    check("f() * g() == 5")
+    check("not f()")
+    check("not (f() and g() or 0)")
+    check("f() == g()")
+    i = 4
+    check("i == f()")
+    check("len(f()) == 0")
+    check("isinstance(2+3+4, float)")
+
+    run("x = i")
+    check("x == 5")
+
+    run("assert not f(), 'oops'")
+    run("a, b, c = 1, 2")
+    run("a, b, c = f()")
+
+    check("max([f(),g()]) == 4")
+    check("'hello'[g()] == 'h'")
+    run("'guk%d' % h(f())")

_pytest/assertion/reinterpret.py

@@ -0,0 +1,48 @@
+import sys
+import py
+
+BuiltinAssertionError = py.builtin.builtins.AssertionError
+
+class AssertionError(BuiltinAssertionError):
+    def __init__(self, *args):
+        BuiltinAssertionError.__init__(self, *args)
+        if args:
+            try:
+                self.msg = str(args[0])
+            except py.builtin._sysex:
+                raise
+            except:
+                self.msg = "<[broken __repr__] %s at %0xd>" %(
+                    args[0].__class__, id(args[0]))
+        else:
+            f = py.code.Frame(sys._getframe(1))
+            try:
+                source = f.code.fullsource
+                if source is not None:
+                    try:
+                        source = source.getstatement(f.lineno, assertion=True)
+                    except IndexError:
+                        source = None
+                    else:
+                        source = str(source.deindent()).strip()
+            except py.error.ENOENT:
+                source = None
+                # this can also occur during reinterpretation, when the
+                # co_filename is set to "<run>".
+            if source:
+                self.msg = reinterpret(source, f, should_fail=True)
+            else:
+                self.msg = "<could not determine information>"
+            if not self.args:
+                self.args = (self.msg,)
+
+if sys.version_info > (3, 0):
+    AssertionError.__module__ = "builtins"
+    reinterpret_old = "old reinterpretation not available for py3"
+else:
+    from _pytest.assertion.oldinterpret import interpret as reinterpret_old
+if sys.version_info >= (2, 6) or (sys.platform.startswith("java")):
+    from _pytest.assertion.newinterpret import interpret as reinterpret
+else:
+    reinterpret = reinterpret_old
+

_pytest/assertion/rewrite.py

@@ -0,0 +1,340 @@
+"""Rewrite assertion AST to produce nice error messages"""
+
+import ast
+import collections
+import itertools
+import sys
+
+import py
+from _pytest.assertion import util
+
+
+def rewrite_asserts(mod):
+    """Rewrite the assert statements in mod."""
+    AssertionRewriter().run(mod)
+
+
+_saferepr = py.io.saferepr
+from _pytest.assertion.util import format_explanation as _format_explanation
+
+def _format_boolop(operands, explanations, is_or):
+    show_explanations = []
+    for operand, expl in zip(operands, explanations):
+        show_explanations.append(expl)
+        if operand == is_or:
+            break
+    return "(" + (is_or and " or " or " and ").join(show_explanations) + ")"
+
+def _call_reprcompare(ops, results, expls, each_obj):
+    for i, res, expl in zip(range(len(ops)), results, expls):
+        try:
+            done = not res
+        except Exception:
+            done = True
+        if done:
+            break
+    if util._reprcompare is not None:
+        custom = util._reprcompare(ops[i], each_obj[i], each_obj[i + 1])
+        if custom is not None:
+            return custom
+    return expl
+
+
+unary_map = {
+    ast.Not : "not %s",
+    ast.Invert : "~%s",
+    ast.USub : "-%s",
+    ast.UAdd : "+%s"
+}
+
+binop_map = {
+    ast.BitOr : "|",
+    ast.BitXor : "^",
+    ast.BitAnd : "&",
+    ast.LShift : "<<",
+    ast.RShift : ">>",
+    ast.Add : "+",
+    ast.Sub : "-",
+    ast.Mult : "*",
+    ast.Div : "/",
+    ast.FloorDiv : "//",
+    ast.Mod : "%",
+    ast.Eq : "==",
+    ast.NotEq : "!=",
+    ast.Lt : "<",
+    ast.LtE : "<=",
+    ast.Gt : ">",
+    ast.GtE : ">=",
+    ast.Pow : "**",
+    ast.Is : "is",
+    ast.IsNot : "is not",
+    ast.In : "in",
+    ast.NotIn : "not in"
+}
+
+
+def set_location(node, lineno, col_offset):
+    """Set node location information recursively."""
+    def _fix(node, lineno, col_offset):
+        if "lineno" in node._attributes:
+            node.lineno = lineno
+        if "col_offset" in node._attributes:
+            node.col_offset = col_offset
+        for child in ast.iter_child_nodes(node):
+            _fix(child, lineno, col_offset)
+    _fix(node, lineno, col_offset)
+    return node
+
+
+class AssertionRewriter(ast.NodeVisitor):
+
+    def run(self, mod):
+        """Find all assert statements in *mod* and rewrite them."""
+        if not mod.body:
+            # Nothing to do.
+            return
+        # Insert some special imports at the top of the module but after any
+        # docstrings and __future__ imports.
+        aliases = [ast.alias(py.builtin.builtins.__name__, "@py_builtins"),
+                   ast.alias("_pytest.assertion.rewrite", "@pytest_ar")]
+        expect_docstring = True
+        pos = 0
+        lineno = 0
+        for item in mod.body:
+            if (expect_docstring and isinstance(item, ast.Expr) and
+                isinstance(item.value, ast.Str)):
+                doc = item.value.s
+                if "PYTEST_DONT_REWRITE" in doc:
+                    # The module has disabled assertion rewriting.
+                    return
+                lineno += len(doc) - 1
+                expect_docstring = False
+            elif (not isinstance(item, ast.ImportFrom) or item.level > 0 and
+                  item.identifier != "__future__"):
+                lineno = item.lineno
+                break
+            pos += 1
+        imports = [ast.Import([alias], lineno=lineno, col_offset=0)
+                   for alias in aliases]
+        mod.body[pos:pos] = imports
+        # Collect asserts.
+        nodes = collections.deque([mod])
+        while nodes:
+            node = nodes.popleft()
+            for name, field in ast.iter_fields(node):
+                if isinstance(field, list):
+                    new = []
+                    for i, child in enumerate(field):
+                        if isinstance(child, ast.Assert):
+                            # Transform assert.
+                            new.extend(self.visit(child))
+                        else:
+                            new.append(child)
+                            if isinstance(child, ast.AST):
+                                nodes.append(child)
+                    setattr(node, name, new)
+                elif (isinstance(field, ast.AST) and
+                      # Don't recurse into expressions as they can't contain
+                      # asserts.
+                      not isinstance(field, ast.expr)):
+                    nodes.append(field)
+
+    def variable(self):
+        """Get a new variable."""
+        # Use a character invalid in python identifiers to avoid clashing.
+        name = "@py_assert" + str(next(self.variable_counter))
+        self.variables.add(name)
+        return name
+
+    def assign(self, expr):
+        """Give *expr* a name."""
+        name = self.variable()
+        self.statements.append(ast.Assign([ast.Name(name, ast.Store())], expr))
+        return ast.Name(name, ast.Load())
+
+    def display(self, expr):
+        """Call py.io.saferepr on the expression."""
+        return self.helper("saferepr", expr)
+
+    def helper(self, name, *args):
+        """Call a helper in this module."""
+        py_name = ast.Name("@pytest_ar", ast.Load())
+        attr = ast.Attribute(py_name, "_" + name, ast.Load())
+        return ast.Call(attr, list(args), [], None, None)
+
+    def builtin(self, name):
+        """Return the builtin called *name*."""
+        builtin_name = ast.Name("@py_builtins", ast.Load())
+        return ast.Attribute(builtin_name, name, ast.Load())
+
+    def explanation_param(self, expr):
+        specifier = "py" + str(next(self.variable_counter))
+        self.explanation_specifiers[specifier] = expr
+        return "%(" + specifier + ")s"
+
+    def push_format_context(self):
+        self.explanation_specifiers = {}
+        self.stack.append(self.explanation_specifiers)
+
+    def pop_format_context(self, expl_expr):
+        current = self.stack.pop()
+        if self.stack:
+            self.explanation_specifiers = self.stack[-1]
+        keys = [ast.Str(key) for key in current.keys()]
+        format_dict = ast.Dict(keys, list(current.values()))
+        form = ast.BinOp(expl_expr, ast.Mod(), format_dict)
+        name = "@py_format" + str(next(self.variable_counter))
+        self.on_failure.append(ast.Assign([ast.Name(name, ast.Store())], form))
+        return ast.Name(name, ast.Load())
+
+    def generic_visit(self, node):
+        """Handle expressions we don't have custom code for."""
+        assert isinstance(node, ast.expr)
+        res = self.assign(node)
+        return res, self.explanation_param(self.display(res))
+
+    def visit_Assert(self, assert_):
+        if assert_.msg:
+            # There's already a message. Don't mess with it.
+            return [assert_]
+        self.statements = []
+        self.variables = set()
+        self.variable_counter = itertools.count()
+        self.stack = []
+        self.on_failure = []
+        self.push_format_context()
+        # Rewrite assert into a bunch of statements.
+        top_condition, explanation = self.visit(assert_.test)
+        # Create failure message.
+        body = self.on_failure
+        negation = ast.UnaryOp(ast.Not(), top_condition)
+        self.statements.append(ast.If(negation, body, []))
+        explanation = "assert " + explanation
+        template = ast.Str(explanation)
+        msg = self.pop_format_context(template)
+        fmt = self.helper("format_explanation", msg)
+        err_name = ast.Name("AssertionError", ast.Load())
+        exc = ast.Call(err_name, [fmt], [], None, None)
+        if sys.version_info[0] >= 3:
+            raise_ = ast.Raise(exc, None)
+        else:
+            raise_ = ast.Raise(exc, None, None)
+        body.append(raise_)
+        # Delete temporary variables.
+        names = [ast.Name(name, ast.Del()) for name in self.variables]
+        if names:
+            delete = ast.Delete(names)
+            self.statements.append(delete)
+        # Fix line numbers.
+        for stmt in self.statements:
+            set_location(stmt, assert_.lineno, assert_.col_offset)
+        return self.statements
+
+    def visit_Name(self, name):
+        # Check if the name is local or not.
+        locs = ast.Call(self.builtin("locals"), [], [], None, None)
+        globs = ast.Call(self.builtin("globals"), [], [], None, None)
+        ops = [ast.In(), ast.IsNot()]
+        test = ast.Compare(ast.Str(name.id), ops, [locs, globs])
+        expr = ast.IfExp(test, self.display(name), ast.Str(name.id))
+        return name, self.explanation_param(expr)
+
+    def visit_BoolOp(self, boolop):
+        operands = []
+        explanations = []
+        self.push_format_context()
+        for operand in boolop.values:
+            res, explanation = self.visit(operand)
+            operands.append(res)
+            explanations.append(explanation)
+        expls = ast.Tuple([ast.Str(expl) for expl in explanations], ast.Load())
+        is_or = ast.Num(isinstance(boolop.op, ast.Or))
+        expl_template = self.helper("format_boolop",
+                                    ast.Tuple(operands, ast.Load()), expls,
+                                    is_or)
+        expl = self.pop_format_context(expl_template)
+        res = self.assign(ast.BoolOp(boolop.op, operands))
+        return res, self.explanation_param(expl)
+
+    def visit_UnaryOp(self, unary):
+        pattern = unary_map[unary.op.__class__]
+        operand_res, operand_expl = self.visit(unary.operand)
+        res = self.assign(ast.UnaryOp(unary.op, operand_res))
+        return res, pattern % (operand_expl,)
+
+    def visit_BinOp(self, binop):
+        symbol = binop_map[binop.op.__class__]
+        left_expr, left_expl = self.visit(binop.left)
+        right_expr, right_expl = self.visit(binop.right)
+        explanation = "(%s %s %s)" % (left_expl, symbol, right_expl)
+        res = self.assign(ast.BinOp(left_expr, binop.op, right_expr))
+        return res, explanation
+
+    def visit_Call(self, call):
+        new_func, func_expl = self.visit(call.func)
+        arg_expls = []
+        new_args = []
+        new_kwargs = []
+        new_star = new_kwarg = None
+        for arg in call.args:
+            res, expl = self.visit(arg)
+            new_args.append(res)
+            arg_expls.append(expl)
+        for keyword in call.keywords:
+            res, expl = self.visit(keyword.value)
+            new_kwargs.append(ast.keyword(keyword.arg, res))
+            arg_expls.append(keyword.arg + "=" + expl)
+        if call.starargs:
+            new_star, expl = self.visit(call.starargs)
+            arg_expls.append("*" + expl)
+        if call.kwargs:
+            new_kwarg, expl = self.visit(call.kwarg)
+            arg_expls.append("**" + expl)
+        expl = "%s(%s)" % (func_expl, ', '.join(arg_expls))
+        new_call = ast.Call(new_func, new_args, new_kwargs, new_star, new_kwarg)
+        res = self.assign(new_call)
+        res_expl = self.explanation_param(self.display(res))
+        outer_expl = "%s\n{%s = %s\n}" % (res_expl, res_expl, expl)
+        return res, outer_expl
+
+    def visit_Attribute(self, attr):
+        if not isinstance(attr.ctx, ast.Load):
+            return self.generic_visit(attr)
+        value, value_expl = self.visit(attr.value)
+        res = self.assign(ast.Attribute(value, attr.attr, ast.Load()))
+        res_expl = self.explanation_param(self.display(res))
+        pat = "%s\n{%s = %s.%s\n}"
+        expl = pat % (res_expl, res_expl, value_expl, attr.attr)
+        return res, expl
+
+    def visit_Compare(self, comp):
+        self.push_format_context()
+        left_res, left_expl = self.visit(comp.left)
+        res_variables = [self.variable() for i in range(len(comp.ops))]
+        load_names = [ast.Name(v, ast.Load()) for v in res_variables]
+        store_names = [ast.Name(v, ast.Store()) for v in res_variables]
+        it = zip(range(len(comp.ops)), comp.ops, comp.comparators)
+        expls = []
+        syms = []
+        results = [left_res]
+        for i, op, next_operand in it:
+            next_res, next_expl = self.visit(next_operand)
+            results.append(next_res)
+            sym = binop_map[op.__class__]
+            syms.append(ast.Str(sym))
+            expl = "%s %s %s" % (left_expl, sym, next_expl)
+            expls.append(ast.Str(expl))
+            res_expr = ast.Compare(left_res, [op], [next_res])
+            self.statements.append(ast.Assign([store_names[i]], res_expr))
+            left_res, left_expl = next_res, next_expl
+        # Use py.code._reprcompare if that's available.
+        expl_call = self.helper("call_reprcompare",
+                                ast.Tuple(syms, ast.Load()),
+                                ast.Tuple(load_names, ast.Load()),
+                                ast.Tuple(expls, ast.Load()),
+                                ast.Tuple(results, ast.Load()))
+        if len(comp.ops) > 1:
+            res = ast.BoolOp(ast.And(), load_names)
+        else:
+            res = load_names[0]
+        return res, self.explanation_param(self.pop_format_context(expl_call))

_pytest/assertion/util.py

@@ -1,43 +1,57 @@
-"""
+"""Utilities for assertion debugging"""
-support for presented detailed information in failing assertions.
+
-"""
 import py
-import sys
-from _pytest.monkeypatch import monkeypatch
 
-def pytest_addoption(parser):
-    group = parser.getgroup("debugconfig")
-    group._addoption('--no-assert', action="store_true", default=False,
-        dest="noassert",
-        help="disable python assert expression reinterpretation."),
 
-def pytest_configure(config):
+# The _reprcompare attribute on the util module is used by the new assertion
-    # The _reprcompare attribute on the py.code module is used by
+# interpretation code and assertion rewriter to detect this plugin was
-    # py._code._assertionnew to detect this plugin was loaded and in
+# loaded and in turn call the hooks defined here as part of the
-    # turn call the hooks defined here as part of the
+# DebugInterpreter.
-    # DebugInterpreter.
+_reprcompare = None
-    m = monkeypatch()
-    config._cleanup.append(m.undo)
-    warn_about_missing_assertion()
-    if not config.getvalue("noassert") and not config.getvalue("nomagic"):
-        def callbinrepr(op, left, right):
-            hook_result = config.hook.pytest_assertrepr_compare(
-                config=config, op=op, left=left, right=right)
-            for new_expl in hook_result:
-                if new_expl:
-                    return '\n~'.join(new_expl)
-        m.setattr(py.builtin.builtins,
-                  'AssertionError', py.code._AssertionError)
-        m.setattr(py.code, '_reprcompare', callbinrepr)
 
-def warn_about_missing_assertion():
+def format_explanation(explanation):
-    try:
+    """This formats an explanation
-        assert False
+
-    except AssertionError:
+    Normally all embedded newlines are escaped, however there are
-        pass
+    three exceptions: \n{, \n} and \n~.  The first two are intended
+    cover nested explanations, see function and attribute explanations
+    for examples (.visit_Call(), visit_Attribute()).  The last one is
+    for when one explanation needs to span multiple lines, e.g. when
+    displaying diffs.
+    """
+    raw_lines = (explanation or '').split('\n')
+    # escape newlines not followed by {, } and ~
+    lines = [raw_lines[0]]
+    for l in raw_lines[1:]:
+        if l.startswith('{') or l.startswith('}') or l.startswith('~'):
+            lines.append(l)
         else:
-        sys.stderr.write("WARNING: failing tests may report as passing because "
+            lines[-1] += '\\n' + l
-        "assertions are turned off!  (are you using python -O?)\n")
+
+    result = lines[:1]
+    stack = [0]
+    stackcnt = [0]
+    for line in lines[1:]:
+        if line.startswith('{'):
+            if stackcnt[-1]:
+                s = 'and   '
+            else:
+                s = 'where '
+            stack.append(len(result))
+            stackcnt[-1] += 1
+            stackcnt.append(0)
+            result.append(' +' + '  '*(len(stack)-1) + s + line[1:])
+        elif line.startswith('}'):
+            assert line.startswith('}')
+            stack.pop()
+            stackcnt.pop()
+            result[stack[-1]] += line[1:]
+        else:
+            assert line.startswith('~')
+            result.append('  '*len(stack) + line[1:])
+    assert len(stack) == 1
+    return '\n'.join(result)
+
 
 # Provide basestring in python3
 try:
@@ -46,7 +60,7 @@ except NameError:
     basestring = str
 
 
-def pytest_assertrepr_compare(op, left, right):
+def assertrepr_compare(op, left, right):
     """return specialised explanations for some operators/operands"""
     width = 80 - 15 - len(op) - 2 # 15 chars indentation, 1 space around op
     left_repr = py.io.saferepr(left, maxsize=int(width/2))

_pytest/helpconfig.py

@@ -16,9 +16,6 @@ def pytest_addoption(parser):
     group.addoption('--traceconfig',
                action="store_true", dest="traceconfig", default=False,
                help="trace considerations of conftest.py files."),
-    group._addoption('--nomagic',
-               action="store_true", dest="nomagic", default=False,
-               help="don't reinterpret asserts, no traceback cutting. ")
     group.addoption('--debug',
                action="store_true", dest="debug", default=False,
                help="generate and show internal debugging information.")

_pytest/main.py

@@ -46,23 +46,22 @@ def pytest_addoption(parser):
 
 
 def pytest_namespace():
-    return dict(collect=dict(Item=Item, Collector=Collector, File=File))
+    collect = dict(Item=Item, Collector=Collector, File=File, Session=Session)
+    return dict(collect=collect)
         
 def pytest_configure(config):
     py.test.config = config # compatibiltiy
     if config.option.exitfirst:
         config.option.maxfail = 1
 
-def pytest_cmdline_main(config):
+def wrap_session(config, doit):
-    """ default command line protocol for initialization, session,
+    """Skeleton command line program"""
-    running tests and reporting. """
     session = Session(config)
     session.exitstatus = EXIT_OK
     try:
         config.pluginmanager.do_configure(config)
         config.hook.pytest_sessionstart(session=session)
-        config.hook.pytest_collection(session=session)
+        doit(config, session)
-        config.hook.pytest_runtestloop(session=session)
     except pytest.UsageError:
         raise
     except KeyboardInterrupt:
@@ -82,13 +81,17 @@ def pytest_cmdline_main(config):
     config.pluginmanager.do_unconfigure(config)
     return session.exitstatus
 
+def pytest_cmdline_main(config):
+    return wrap_session(config, _main)
+
+def _main(config, session):
+    """ default command line protocol for initialization, session,
+    running tests and reporting. """
+    config.hook.pytest_collection(session=session)
+    config.hook.pytest_runtestloop(session=session)
+
 def pytest_collection(session):
-    session.perform_collect()
+    return session.perform_collect()
-    hook = session.config.hook
-    hook.pytest_collection_modifyitems(session=session,
-        config=session.config, items=session.items)
-    hook.pytest_collection_finish(session=session)
-    return True
 
 def pytest_runtestloop(session):
     if session.config.option.collectonly:
@@ -374,6 +377,16 @@ class Session(FSCollector):
         return HookProxy(fspath, self.config)
 
     def perform_collect(self, args=None, genitems=True):
+        hook = self.config.hook
+        try:
+            items = self._perform_collect(args, genitems)
+            hook.pytest_collection_modifyitems(session=self,
+                config=self.config, items=items)
+        finally:
+            hook.pytest_collection_finish(session=self)
+        return items
+
+    def _perform_collect(self, args, genitems):
         if args is None:
             args = self.config.args
         self.trace("perform_collect", self, args)

_pytest/pytester.py

@@ -6,7 +6,7 @@ import re
 import inspect
 import time
 from fnmatch import fnmatch
-from _pytest.main import Session
+from _pytest.main import Session, EXIT_OK
 from py.builtin import print_
 from _pytest.core import HookRelay
 
@@ -292,13 +292,19 @@ class TmpTestdir:
         assert '::' not in str(arg)
         p = py.path.local(arg)
         x = session.fspath.bestrelpath(p)
-        return session.perform_collect([x], genitems=False)[0]
+        config.hook.pytest_sessionstart(session=session)
+        res = session.perform_collect([x], genitems=False)[0]
+        config.hook.pytest_sessionfinish(session=session, exitstatus=EXIT_OK)
+        return res
 
     def getpathnode(self, path):
-        config = self.parseconfig(path)
+        config = self.parseconfigure(path)
         session = Session(config)
         x = session.fspath.bestrelpath(path)
-        return session.perform_collect([x], genitems=False)[0]
+        config.hook.pytest_sessionstart(session=session)
+        res = session.perform_collect([x], genitems=False)[0]
+        config.hook.pytest_sessionfinish(session=session, exitstatus=EXIT_OK)
+        return res
 
     def genitems(self, colitems):
         session = colitems[0].session
@@ -312,7 +318,9 @@ class TmpTestdir:
         config = self.parseconfigure(*args)
         rec = self.getreportrecorder(config)
         session = Session(config)
+        config.hook.pytest_sessionstart(session=session)
         session.perform_collect()
+        config.hook.pytest_sessionfinish(session=session, exitstatus=EXIT_OK)
         return session.items, rec
 
     def runitem(self, source):
@@ -382,6 +390,8 @@ class TmpTestdir:
             c.basetemp = py.path.local.make_numbered_dir(prefix="reparse",
                 keep=0, rootdir=self.tmpdir, lock_timeout=None)
             c.parse(args)
+            c.pluginmanager.do_configure(c)
+            self.request.addfinalizer(lambda: c.pluginmanager.do_unconfigure(c))
             return c
         finally:
             py.test.config = oldconfig

_pytest/python.py

@@ -4,6 +4,7 @@ import inspect
 import sys
 import pytest
 from py._code.code import TerminalRepr
+from _pytest import assertion
 
 import _pytest
 cutdir = py.path.local(_pytest.__file__).dirpath()
@@ -226,8 +227,12 @@ class Module(pytest.File, PyCollectorMixin):
 
     def _importtestmodule(self):
         # we assume we are only called once per module
+        assertion.before_module_import(self)
+        try:
             try:
                 mod = self.fspath.pyimport(ensuresyspath=True)
+            finally:
+                assertion.after_module_import(self)
         except SyntaxError:
             excinfo = py.code.ExceptionInfo()
             raise self.CollectError(excinfo.getrepr(style="short"))
@@ -374,7 +379,7 @@ class Generator(FunctionMixin, PyCollectorMixin, pytest.Collector):
         # test generators are seen as collectors but they also
         # invoke setup/teardown on popular request
         # (induced by the common "test_*" naming shared with normal tests)
-        self.config._setupstate.prepare(self)
+        self.session._setupstate.prepare(self)
         # see FunctionMixin.setup and test_setupstate_is_preserved_134
         self._preservedparent = self.parent.obj
         l = []
@@ -726,7 +731,7 @@ class FuncargRequest:
 
     def _addfinalizer(self, finalizer, scope):
         colitem = self._getscopeitem(scope)
-        self.config._setupstate.addfinalizer(
+        self._pyfuncitem.session._setupstate.addfinalizer(
             finalizer=finalizer, colitem=colitem)
 
     def __repr__(self):
@@ -747,8 +752,10 @@ class FuncargRequest:
         raise self.LookupError(msg)
 
 def showfuncargs(config):
-    from _pytest.main import Session
+    from _pytest.main import wrap_session
-    session = Session(config)
+    return wrap_session(config, _showfuncargs_main)
+
+def _showfuncargs_main(config, session):
     session.perform_collect()
     if session.items:
         plugins = session.items[0].getplugins()

_pytest/runner.py

@@ -14,12 +14,10 @@ def pytest_namespace():
 #
 # pytest plugin hooks
 
-# XXX move to pytest_sessionstart and fix py.test owns tests
+def pytest_sessionstart(session):
-def pytest_configure(config):
+    session._setupstate = SetupState()
-    config._setupstate = SetupState()
 
 def pytest_sessionfinish(session, exitstatus):
-    if hasattr(session.config, '_setupstate'):
     hook = session.config.hook
     rep = hook.pytest__teardown_final(session=session)
     if rep:
@@ -46,16 +44,16 @@ def runtestprotocol(item, log=True):
     return reports
 
 def pytest_runtest_setup(item):
-    item.config._setupstate.prepare(item)
+    item.session._setupstate.prepare(item)
 
 def pytest_runtest_call(item):
     item.runtest()
 
 def pytest_runtest_teardown(item):
-    item.config._setupstate.teardown_exact(item)
+    item.session._setupstate.teardown_exact(item)
 
 def pytest__teardown_final(session):
-    call = CallInfo(session.config._setupstate.teardown_all, when="teardown")
+    call = CallInfo(session._setupstate.teardown_all, when="teardown")
     if call.excinfo:
         ntraceback = call.excinfo.traceback .cut(excludepath=py._pydir)
         call.excinfo.traceback = ntraceback.filter()

doc/assert.txt

@@ -18,8 +18,8 @@ following::
     def test_function():
         assert f() == 4
 
-to assert that your object returns a certain value. If this
+to assert that your function returns a certain value. If this assertion fails
-assertion fails you will see the value of ``x``::
+you will see the value of ``x``::
 
     $ py.test test_assert1.py
     =========================== test session starts ============================
@@ -39,22 +39,12 @@ assertion fails you will see the value of ``x``::
     test_assert1.py:5: AssertionError
     ========================= 1 failed in 0.02 seconds =========================
 
-Reporting details about the failing assertion is achieved by re-evaluating
+py.test has support for showing the values of the most common subexpressions
-the assert expression and recording the intermediate values.
+including calls, attributes, comparisons, and binary and unary operators. This
+allows you to use the idiomatic python constructs without boilerplate code while
+not losing introspection information.
 
-Note: If evaluating the assert expression has side effects you may get a
+See :ref:`assert-details` for more information on assertion introspection.
-warning that the intermediate values could not be determined safely.  A
-common example of this issue is an assertion which reads from a file::
-
-        assert f.read() != '...'
-
-If this assertion fails then the re-evaluation will probably succeed!
-This is because ``f.read()`` will return an empty string when it is
-called the second time during the re-evaluation.  However, it is
-easy to rewrite the assertion and avoid any trouble::
-
-        content = f.read()
-        assert content != '...'
 
 
 assertions about expected exceptions
@@ -137,6 +127,66 @@ Special comparisons are done for a number of cases:
 
 See the :ref:`reporting demo <tbreportdemo>` for many more examples.
 
+
+.. _assert-details:
+
+Assertion introspection details
+-------------------------------
+
+Reporting details about the failing assertion is achieved either by rewriting
+assert statements before they are run or re-evaluating the assert expression and
+recording the intermediate values. Which technique is used depends on the
+location of the assert, py.test's configuration, and Python version being used
+to run py.test.
+
+By default, if the Python version is greater than or equal to 2.6, py.test
+rewrites assert statements in test modules. Rewritten assert statements put
+introspection information into the assertion failure message. Note py.test only
+rewrites test modules directly discovered by its test collection process, so
+asserts in supporting modules will not be rewritten.
+
+.. note::
+
+   py.test rewrites test modules as it collects tests from them. It does this by
+   writing a new pyc file which Python loads when the test module is
+   imported. If the module has already been loaded (it is in sys.modules),
+   though, Python will not load the rewritten module. This means if a test
+   module imports another test module which has not already been rewritten, then
+   py.test will not be able to rewrite the second module.
+
+If an assert statement has not been rewritten or the Python version is less than
+2.6, py.test falls back on assert reinterpretation. In assert reinterpretation,
+py.test walks the frame of the function containing the assert statement to
+discover sub-expression results of the failing assert statement. You can force
+py.test to always use assertion reinterpretation by passing the
+``--assertmode=old`` option.
+
+Assert reinterpretation has a caveat not present with assert rewriting: If
+evaluating the assert expression has side effects you may get a warning that the
+intermediate values could not be determined safely.  A common example of this
+issue is an assertion which reads from a file::
+
+        assert f.read() != '...'
+
+If this assertion fails then the re-evaluation will probably succeed!
+This is because ``f.read()`` will return an empty string when it is
+called the second time during the re-evaluation.  However, it is
+easy to rewrite the assertion and avoid any trouble::
+
+        content = f.read()
+        assert content != '...'
+
+All assert introspection can be turned off by passing ``--assertmode=off``.
+
+.. versionadded:: 2.1
+
+   Add assert rewriting as an alternate introspection technique.
+
+.. versionchanged:: 2.1
+
+   Introduce the ``--assertmode`` option. Deprecate ``--no-assert`` and
+   ``--nomagic``.
+
 ..
     Defining your own comparison
     ----------------------------------------------

doc/faq.txt

@@ -47,13 +47,17 @@ customizable testing frameworks for Python.   However,
 ``py.test`` still uses many metaprogramming techniques and
 reading its source is thus likely not something for Python beginners.
 
-A second "magic" issue arguably the assert statement re-intepreation:
+A second "magic" issue arguably the assert statement debugging feature. When
-When an ``assert`` statement fails, py.test re-interprets the expression
+loading test modules py.test rewrites the source code of assert statements. When
-to show intermediate values if a test fails.  If your expression
+a rewritten assert statement fails, its error message has more information than
-has side effects (better to avoid them anyway!) the intermediate values
+the original. py.test also has a second assert debugging technique. When an
-may not be the same, obfuscating the initial error (this is also
+``assert`` statement that was missed by the rewriter fails, py.test
-explained at the command line if it happens).
+re-interprets the expression to show intermediate values if a test fails. This
-``py.test --no-assert`` turns off assert re-interpretation.
+second technique suffers from caveat that the rewriting does not: If your
+expression has side effects (better to avoid them anyway!)  the intermediate
+values may not be the same, confusing the reinterpreter and obfuscating the
+initial error (this is also explained at the command line if it happens).
+You can turn off all assertion debugging with ``py.test --assertmode=off``.
 
 .. _`py namespaces`: index.html
 .. _`py/__init__.py`: http://bitbucket.org/hpk42/py-trunk/src/trunk/py/__init__.py

setup.py

@@ -22,14 +22,14 @@ def main():
         name='pytest',
         description='py.test: simple powerful testing with Python',
         long_description = long_description,
-        version='2.1.0.dev1',
+        version='2.1.0.dev2',
         url='http://pytest.org',
         license='MIT license',
         platforms=['unix', 'linux', 'osx', 'cygwin', 'win32'],
         author='holger krekel, Guido Wesdorp, Carl Friedrich Bolz, Armin Rigo, Maciej Fijalkowski & others',
         author_email='holger at merlinux.eu',
         entry_points= make_entry_points(),
-        install_requires=['py>1.4.1'],
+        install_requires=['py>1.4.3'],
         classifiers=['Development Status :: 5 - Production/Stable',
                      'Intended Audience :: Developers',
                      'License :: OSI Approved :: MIT License',

testing/test_assertinterpret.py

@@ -0,0 +1,327 @@
+"PYTEST_DONT_REWRITE"
+import pytest, py
+
+from _pytest.assertion import util
+
+def exvalue():
+    return py.std.sys.exc_info()[1]
+
+def f():
+    return 2
+
+def test_not_being_rewritten():
+    assert "@py_builtins" not in globals()
+
+def test_assert():
+    try:
+        assert f() == 3
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith('assert 2 == 3\n')
+
+def test_assert_with_explicit_message():
+    try:
+        assert f() == 3, "hello"
+    except AssertionError:
+        e = exvalue()
+        assert e.msg == 'hello'
+
+def test_assert_within_finally():
+    class A:
+        def f():
+            pass
+    excinfo = py.test.raises(TypeError, """
+        try:
+            A().f()
+        finally:
+            i = 42
+    """)
+    s = excinfo.exconly()
+    assert s.find("takes no argument") != -1
+
+    #def g():
+    #    A.f()
+    #excinfo = getexcinfo(TypeError, g)
+    #msg = getmsg(excinfo)
+    #assert msg.find("must be called with A") != -1
+
+
+def test_assert_multiline_1():
+    try:
+        assert (f() ==
+                3)
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith('assert 2 == 3\n')
+
+def test_assert_multiline_2():
+    try:
+        assert (f() == (4,
+                   3)[-1])
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith('assert 2 ==')
+
+def test_in():
+    try:
+        assert "hi" in [1, 2]
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith("assert 'hi' in")
+
+def test_is():
+    try:
+        assert 1 is 2
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith("assert 1 is 2")
+
+
+@py.test.mark.skipif("sys.version_info < (2,6)")
+def test_attrib():
+    class Foo(object):
+        b = 1
+    i = Foo()
+    try:
+        assert i.b == 2
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith("assert 1 == 2")
+
+@py.test.mark.skipif("sys.version_info < (2,6)")
+def test_attrib_inst():
+    class Foo(object):
+        b = 1
+    try:
+        assert Foo().b == 2
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith("assert 1 == 2")
+
+def test_len():
+    l = list(range(42))
+    try:
+        assert len(l) == 100
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert s.startswith("assert 42 == 100")
+        assert "where 42 = len([" in s
+
+def test_assert_non_string_message():
+    class A:
+        def __str__(self):
+            return "hello"
+    try:
+        assert 0 == 1, A()
+    except AssertionError:
+        e = exvalue()
+        assert e.msg == "hello"
+
+def test_assert_keyword_arg():
+    def f(x=3):
+        return False
+    try:
+        assert f(x=5)
+    except AssertionError:
+        e = exvalue()
+        assert "x=5" in e.msg
+
+# These tests should both fail, but should fail nicely...
+class WeirdRepr:
+    def __repr__(self):
+        return '<WeirdRepr\nsecond line>'
+
+def bug_test_assert_repr():
+    v = WeirdRepr()
+    try:
+        assert v == 1
+    except AssertionError:
+        e = exvalue()
+        assert e.msg.find('WeirdRepr') != -1
+        assert e.msg.find('second line') != -1
+        assert 0
+
+def test_assert_non_string():
+    try:
+        assert 0, ['list']
+    except AssertionError:
+        e = exvalue()
+        assert e.msg.find("list") != -1
+
+def test_assert_implicit_multiline():
+    try:
+        x = [1,2,3]
+        assert x != [1,
+           2, 3]
+    except AssertionError:
+        e = exvalue()
+        assert e.msg.find('assert [1, 2, 3] !=') != -1
+
+
+def test_assert_with_brokenrepr_arg():
+    class BrokenRepr:
+        def __repr__(self): 0 / 0
+    e = AssertionError(BrokenRepr())
+    if e.msg.find("broken __repr__") == -1:
+        py.test.fail("broken __repr__ not handle correctly")
+
+def test_multiple_statements_per_line():
+    try:
+        a = 1; assert a == 2
+    except AssertionError:
+        e = exvalue()
+        assert "assert 1 == 2" in e.msg
+
+def test_power():
+    try:
+        assert 2**3 == 7
+    except AssertionError:
+        e = exvalue()
+        assert "assert (2 ** 3) == 7" in e.msg
+
+
+class TestView:
+
+    def setup_class(cls):
+        cls.View = pytest.importorskip("_pytest.assertion.oldinterpret").View
+
+    def test_class_dispatch(self):
+        ### Use a custom class hierarchy with existing instances
+
+        class Picklable(self.View):
+            pass
+
+        class Simple(Picklable):
+            __view__ = object
+            def pickle(self):
+                return repr(self.__obj__)
+
+        class Seq(Picklable):
+            __view__ = list, tuple, dict
+            def pickle(self):
+                return ';'.join(
+                    [Picklable(item).pickle() for item in self.__obj__])
+
+        class Dict(Seq):
+            __view__ = dict
+            def pickle(self):
+                return Seq.pickle(self) + '!' + Seq(self.values()).pickle()
+
+        assert Picklable(123).pickle() == '123'
+        assert Picklable([1,[2,3],4]).pickle() == '1;2;3;4'
+        assert Picklable({1:2}).pickle() == '1!2'
+
+    def test_viewtype_class_hierarchy(self):
+        # Use a custom class hierarchy based on attributes of existing instances
+        class Operation:
+            "Existing class that I don't want to change."
+            def __init__(self, opname, *args):
+                self.opname = opname
+                self.args = args
+
+        existing = [Operation('+', 4, 5),
+                    Operation('getitem', '', 'join'),
+                    Operation('setattr', 'x', 'y', 3),
+                    Operation('-', 12, 1)]
+
+        class PyOp(self.View):
+            def __viewkey__(self):
+                return self.opname
+            def generate(self):
+                return '%s(%s)' % (self.opname, ', '.join(map(repr, self.args)))
+
+        class PyBinaryOp(PyOp):
+            __view__ = ('+', '-', '*', '/')
+            def generate(self):
+                return '%s %s %s' % (self.args[0], self.opname, self.args[1])
+
+        codelines = [PyOp(op).generate() for op in existing]
+        assert codelines == ["4 + 5", "getitem('', 'join')",
+            "setattr('x', 'y', 3)", "12 - 1"]
+
+@py.test.mark.skipif("sys.version_info < (2,6)")
+def test_assert_customizable_reprcompare(monkeypatch):
+    monkeypatch.setattr(util, '_reprcompare', lambda *args: 'hello')
+    try:
+        assert 3 == 4
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert "hello" in s
+
+def test_assert_long_source_1():
+    try:
+        assert len == [
+            (None, ['somet text', 'more text']),
+        ]
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert 're-run' not in s
+        assert 'somet text' in s
+
+def test_assert_long_source_2():
+    try:
+        assert(len == [
+            (None, ['somet text', 'more text']),
+        ])
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert 're-run' not in s
+        assert 'somet text' in s
+
+def test_assert_raise_alias(testdir):
+    testdir.makepyfile("""
+    "PYTEST_DONT_REWRITE"
+    import sys
+    EX = AssertionError
+    def test_hello():
+        raise EX("hello"
+            "multi"
+            "line")
+    """)
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines([
+        "*def test_hello*",
+        "*raise EX*",
+        "*1 failed*",
+    ])
+
+
+@pytest.mark.skipif("sys.version_info < (2,5)")
+def test_assert_raise_subclass():
+    class SomeEx(AssertionError):
+        def __init__(self, *args):
+            super(SomeEx, self).__init__()
+    try:
+        raise SomeEx("hello")
+    except AssertionError:
+        s = str(exvalue())
+        assert 're-run' not in s
+        assert 'could not determine' in s
+
+def test_assert_raises_in_nonzero_of_object_pytest_issue10():
+    class A(object):
+        def __nonzero__(self):
+            raise ValueError(42)
+        def __lt__(self, other):
+            return A()
+        def __repr__(self):
+            return "<MY42 object>"
+    def myany(x):
+        return True
+    try:
+        assert not(myany(A() < 0))
+    except AssertionError:
+        e = exvalue()
+        s = str(e)
+        assert "<MY42 object> < 0" in s

testing/test_assertion.py

@@ -2,11 +2,12 @@ import sys
 
 import py, pytest
 import _pytest.assertion as plugin
+from _pytest.assertion import reinterpret, util
 
 needsnewassert = pytest.mark.skipif("sys.version_info < (2,6)")
 
 def interpret(expr):
-    return py.code._reinterpret(expr, py.code.Frame(sys._getframe(1)))
+    return reinterpret.reinterpret(expr, py.code.Frame(sys._getframe(1)))
 
 class TestBinReprIntegration:
     pytestmark = needsnewassert
@@ -25,7 +26,7 @@ class TestBinReprIntegration:
                 self.right = right
         mockhook = MockHook()
         monkeypatch = request.getfuncargvalue("monkeypatch")
-        monkeypatch.setattr(py.code, '_reprcompare', mockhook)
+        monkeypatch.setattr(util, '_reprcompare', mockhook)
         return mockhook
 
     def test_pytest_assertrepr_compare_called(self, hook):
@@ -40,13 +41,13 @@ class TestBinReprIntegration:
         assert hook.right == [0, 2]
 
     def test_configure_unconfigure(self, testdir, hook):
-        assert hook == py.code._reprcompare
+        assert hook == util._reprcompare
         config = testdir.parseconfig()
         plugin.pytest_configure(config)
-        assert hook != py.code._reprcompare
+        assert hook != util._reprcompare
         from _pytest.config import pytest_unconfigure
         pytest_unconfigure(config)
-        assert hook == py.code._reprcompare
+        assert hook == util._reprcompare
 
 def callequal(left, right):
     return plugin.pytest_assertrepr_compare('==', left, right)
@@ -119,6 +120,10 @@ class TestAssert_reprcompare:
         expl = ' '.join(callequal('foo', 'bar'))
         assert 'raised in repr()' not in expl
 
+@pytest.mark.skipif("config._assertstate.mode != 'on'")
+def test_rewritten():
+    assert "@py_builtins" in globals()
+
 def test_reprcompare_notin():
     detail = plugin.pytest_assertrepr_compare('not in', 'foo', 'aaafoobbb')[1:]
     assert detail == ["'foo' is contained here:", '  aaafoobbb', '?    +++']
@@ -159,7 +164,7 @@ def test_sequence_comparison_uses_repr(testdir):
     ])
 
 
-def test_functional(testdir):
+def test_assertion_options(testdir):
     testdir.makepyfile("""
         def test_hello():
             x = 3
@@ -167,8 +172,30 @@ def test_functional(testdir):
     """)
     result = testdir.runpytest()
     assert "3 == 4" in result.stdout.str()
-    result = testdir.runpytest("--no-assert")
+    off_options = (("--no-assert",),
+                   ("--nomagic",),
+                   ("--no-assert", "--nomagic"),
+                   ("--assertmode=off",),
+                   ("--assertmode=off", "--no-assert"),
+                   ("--assertmode=off", "--nomagic"),
+                   ("--assertmode=off," "--no-assert", "--nomagic"))
+    for opt in off_options:
+        result = testdir.runpytest(*opt)
         assert "3 == 4" not in result.stdout.str()
+    for mode in "on", "old":
+        for other_opt in off_options[:3]:
+            opt = ("--assertmode=" + mode,) + other_opt
+            result = testdir.runpytest(*opt)
+            assert result.ret == 3
+            assert "assertion options conflict" in result.stderr.str()
+
+def test_old_assert_mode(testdir):
+    testdir.makepyfile("""
+        def test_in_old_mode():
+            assert "@py_builtins" not in globals()
+    """)
+    result = testdir.runpytest("--assertmode=old")
+    assert result.ret == 0
 
 def test_triple_quoted_string_issue113(testdir):
     testdir.makepyfile("""
@@ -221,3 +248,10 @@ def test_warn_missing(testdir):
     result.stderr.fnmatch_lines([
         "*WARNING*assertion*",
     ])
+
+def test_load_fake_pyc(testdir):
+    path = testdir.makepyfile("x = 'hello'")
+    co = compile("x = 'bye'", str(path), "exec")
+    plugin._write_pyc(co, path)
+    mod = path.pyimport()
+    assert mod.x == "bye"

testing/test_assertrewrite.py

@@ -0,0 +1,256 @@
+import sys
+import py
+import pytest
+
+ast = pytest.importorskip("ast")
+
+from _pytest.assertion import util
+from _pytest.assertion.rewrite import rewrite_asserts
+
+
+def setup_module(mod):
+    mod._old_reprcompare = util._reprcompare
+    py.code._reprcompare = None
+
+def teardown_module(mod):
+    util._reprcompare = mod._old_reprcompare
+    del mod._old_reprcompare
+
+
+def rewrite(src):
+    tree = ast.parse(src)
+    rewrite_asserts(tree)
+    return tree
+
+def getmsg(f, extra_ns=None, must_pass=False):
+    """Rewrite the assertions in f, run it, and get the failure message."""
+    src = '\n'.join(py.code.Code(f).source().lines)
+    mod = rewrite(src)
+    code = compile(mod, "<test>", "exec")
+    ns = {}
+    if extra_ns is not None:
+        ns.update(extra_ns)
+    py.builtin.exec_(code, ns)
+    func = ns[f.__name__]
+    try:
+        func()
+    except AssertionError:
+        if must_pass:
+            pytest.fail("shouldn't have raised")
+        s = str(sys.exc_info()[1])
+        if not s.startswith("assert"):
+            return "AssertionError: " + s
+        return s
+    else:
+        if not must_pass:
+            pytest.fail("function didn't raise at all")
+
+
+class TestAssertionRewrite:
+
+    def test_place_initial_imports(self):
+        s = """'Doc string'\nother = stuff"""
+        m = rewrite(s)
+        assert isinstance(m.body[0], ast.Expr)
+        assert isinstance(m.body[0].value, ast.Str)
+        for imp in m.body[1:3]:
+            assert isinstance(imp, ast.Import)
+            assert imp.lineno == 2
+            assert imp.col_offset == 0
+        assert isinstance(m.body[3], ast.Assign)
+        s = """from __future__ import with_statement\nother_stuff"""
+        m = rewrite(s)
+        assert isinstance(m.body[0], ast.ImportFrom)
+        for imp in m.body[1:3]:
+            assert isinstance(imp, ast.Import)
+            assert imp.lineno == 2
+            assert imp.col_offset == 0
+        assert isinstance(m.body[3], ast.Expr)
+        s = """'doc string'\nfrom __future__ import with_statement\nother"""
+        m = rewrite(s)
+        assert isinstance(m.body[0], ast.Expr)
+        assert isinstance(m.body[0].value, ast.Str)
+        assert isinstance(m.body[1], ast.ImportFrom)
+        for imp in m.body[2:4]:
+            assert isinstance(imp, ast.Import)
+            assert imp.lineno == 3
+            assert imp.col_offset == 0
+        assert isinstance(m.body[4], ast.Expr)
+
+    def test_dont_rewrite(self):
+        s = """'PYTEST_DONT_REWRITE'\nassert 14"""
+        m = rewrite(s)
+        assert len(m.body) == 2
+        assert isinstance(m.body[0].value, ast.Str)
+        assert isinstance(m.body[1], ast.Assert)
+        assert m.body[1].msg is None
+
+    def test_name(self):
+        def f():
+            assert False
+        assert getmsg(f) == "assert False"
+        def f():
+            f = False
+            assert f
+        assert getmsg(f) == "assert False"
+        def f():
+            assert a_global
+        assert getmsg(f, {"a_global" : False}) == "assert a_global"
+
+    def test_assert_already_has_message(self):
+        def f():
+            assert False, "something bad!"
+        assert getmsg(f) == "AssertionError: something bad!"
+
+    def test_boolop(self):
+        def f():
+            f = g = False
+            assert f and g
+        assert getmsg(f) == "assert (False)"
+        def f():
+            f = True
+            g = False
+            assert f and g
+        assert getmsg(f) == "assert (True and False)"
+        def f():
+            f = False
+            g = True
+            assert f and g
+        assert getmsg(f) == "assert (False)"
+        def f():
+            f = g = False
+            assert f or g
+        assert getmsg(f) == "assert (False or False)"
+        def f():
+            f = True
+            g = False
+            assert f or g
+        getmsg(f, must_pass=True)
+
+    def test_short_circut_evaluation(self):
+        pytest.xfail("complicated fix; I'm not sure if it's important")
+        def f():
+            assert True or explode
+        getmsg(f, must_pass=True)
+
+    def test_unary_op(self):
+        def f():
+            x = True
+            assert not x
+        assert getmsg(f) == "assert not True"
+        def f():
+            x = 0
+            assert ~x + 1
+        assert getmsg(f) == "assert (~0 + 1)"
+        def f():
+            x = 3
+            assert -x + x
+        assert getmsg(f) == "assert (-3 + 3)"
+        def f():
+            x = 0
+            assert +x + x
+        assert getmsg(f) == "assert (+0 + 0)"
+
+    def test_binary_op(self):
+        def f():
+            x = 1
+            y = -1
+            assert x + y
+        assert getmsg(f) == "assert (1 + -1)"
+
+    def test_call(self):
+        def g(a=42, *args, **kwargs):
+            return False
+        ns = {"g" : g}
+        def f():
+            assert g()
+        assert getmsg(f, ns) == """assert False
+ +  where False = g()"""
+        def f():
+            assert g(1)
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1)"""
+        def f():
+            assert g(1, 2)
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, 2)"""
+        def f():
+            assert g(1, g=42)
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, g=42)"""
+        def f():
+            assert g(1, 3, g=23)
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, 3, g=23)"""
+
+    def test_attribute(self):
+        class X(object):
+            g = 3
+        ns = {"X" : X, "x" : X()}
+        def f():
+            assert not x.g
+        assert getmsg(f, ns) == """assert not 3
+ +  where 3 = x.g"""
+        def f():
+            x.a = False
+            assert x.a
+        assert getmsg(f, ns) == """assert False
+ +  where False = x.a"""
+
+    def test_comparisons(self):
+        def f():
+            a, b = range(2)
+            assert b < a
+        assert getmsg(f) == """assert 1 < 0"""
+        def f():
+            a, b, c = range(3)
+            assert a > b > c
+        assert getmsg(f) == """assert 0 > 1"""
+        def f():
+            a, b, c = range(3)
+            assert a < b > c
+        assert getmsg(f) == """assert 1 > 2"""
+        def f():
+            a, b, c = range(3)
+            assert a < b <= c
+        getmsg(f, must_pass=True)
+        def f():
+            a, b, c = range(3)
+            assert a < b
+            assert b < c
+        getmsg(f, must_pass=True)
+
+    def test_len(self):
+        def f():
+            l = list(range(10))
+            assert len(l) == 11
+        assert getmsg(f).startswith("""assert 10 == 11
+ +  where 10 = len([""")
+
+    def test_custom_reprcompare(self, monkeypatch):
+        def my_reprcompare(op, left, right):
+            return "42"
+        monkeypatch.setattr(util, "_reprcompare", my_reprcompare)
+        def f():
+            assert 42 < 3
+        assert getmsg(f) == "assert 42"
+        def my_reprcompare(op, left, right):
+            return "%s %s %s" % (left, op, right)
+        monkeypatch.setattr(util, "_reprcompare", my_reprcompare)
+        def f():
+            assert 1 < 3 < 5 <= 4 < 7
+        assert getmsg(f) == "assert 5 <= 4"
+
+    def test_assert_raising_nonzero_in_comparison(self):
+        def f():
+            class A(object):
+                def __nonzero__(self):
+                    raise ValueError(42)
+                def __lt__(self, other):
+                    return A()
+                def __repr__(self):
+                    return "<MY42 object>"
+            def myany(x):
+                return False
+            assert myany(A() < 0)
+        assert "<MY42 object> < 0" in getmsg(f)

testing/test_collection.py

@@ -313,7 +313,7 @@ class TestSession:
     def test_collect_topdir(self, testdir):
         p = testdir.makepyfile("def test_func(): pass")
         id = "::".join([p.basename, "test_func"])
-        config = testdir.parseconfig(id)
+        config = testdir.parseconfigure(id)
         topdir = testdir.tmpdir
         rcol = Session(config)
         assert topdir == rcol.fspath
@@ -328,7 +328,7 @@ class TestSession:
     def test_collect_protocol_single_function(self, testdir):
         p = testdir.makepyfile("def test_func(): pass")
         id = "::".join([p.basename, "test_func"])
-        config = testdir.parseconfig(id)
+        config = testdir.parseconfigure(id)
         topdir = testdir.tmpdir
         rcol = Session(config)
         assert topdir == rcol.fspath
@@ -363,7 +363,7 @@ class TestSession:
                    p.basename + "::TestClass::()",
                    normid,
                    ]:
-            config = testdir.parseconfig(id)
+            config = testdir.parseconfigure(id)
             rcol = Session(config=config)
             rcol.perform_collect()
             items = rcol.items
@@ -388,7 +388,7 @@ class TestSession:
         """ % p.basename)
         id = p.basename
 
-        config = testdir.parseconfig(id)
+        config = testdir.parseconfigure(id)
         rcol = Session(config)
         hookrec = testdir.getreportrecorder(config)
         rcol.perform_collect()
@@ -413,7 +413,7 @@ class TestSession:
         aaa = testdir.mkpydir("aaa")
         test_aaa = aaa.join("test_aaa.py")
         p.move(test_aaa)
-        config = testdir.parseconfig()
+        config = testdir.parseconfigure()
         rcol = Session(config)
         hookrec = testdir.getreportrecorder(config)
         rcol.perform_collect()
@@ -437,7 +437,7 @@ class TestSession:
         p.move(test_bbb)
 
         id = "."
-        config = testdir.parseconfig(id)
+        config = testdir.parseconfigure(id)
         rcol = Session(config)
         hookrec = testdir.getreportrecorder(config)
         rcol.perform_collect()
@@ -455,7 +455,7 @@ class TestSession:
 
     def test_serialization_byid(self, testdir):
         p = testdir.makepyfile("def test_func(): pass")
-        config = testdir.parseconfig()
+        config = testdir.parseconfigure()
         rcol = Session(config)
         rcol.perform_collect()
         items = rcol.items
@@ -476,7 +476,7 @@ class TestSession:
                     pass
         """)
         arg = p.basename + ("::TestClass::test_method")
-        config = testdir.parseconfig(arg)
+        config = testdir.parseconfigure(arg)
         rcol = Session(config)
         rcol.perform_collect()
         items = rcol.items

testing/test_python.py

@@ -705,11 +705,11 @@ class TestRequest:
             def test_func(something): pass
         """)
         req = funcargs.FuncargRequest(item)
-        req.config._setupstate.prepare(item) # XXX
+        req._pyfuncitem.session._setupstate.prepare(item) # XXX
         req._fillfuncargs()
         # successively check finalization calls
         teardownlist = item.getparent(pytest.Module).obj.teardownlist
-        ss = item.config._setupstate
+        ss = item.session._setupstate
         assert not teardownlist
         ss.teardown_exact(item)
         print(ss.stack)
@@ -834,11 +834,11 @@ class TestRequestCachedSetup:
         ret1 = req1.cached_setup(setup, teardown, scope="function")
         assert l == ['setup']
         # artificial call of finalizer
-        req1.config._setupstate._callfinalizers(item1)
+        req1._pyfuncitem.session._setupstate._callfinalizers(item1)
         assert l == ["setup", "teardown"]
         ret2 = req1.cached_setup(setup, teardown, scope="function")
         assert l == ["setup", "teardown", "setup"]
-        req1.config._setupstate._callfinalizers(item1)
+        req1._pyfuncitem.session._setupstate._callfinalizers(item1)
         assert l == ["setup", "teardown", "setup", "teardown"]
 
     def test_request_cached_setup_two_args(self, testdir):