test_ok1/_pytest/assertion/rewrite.py

601 lines
22 KiB
Python

"""Rewrite assertion AST to produce nice error messages"""
import ast
import errno
import itertools
import imp
import marshal
import os
import struct
import sys
import types
import py
from _pytest.assertion import util
# Windows gives ENOENT in places *nix gives ENOTDIR.
if sys.platform.startswith("win"):
PATH_COMPONENT_NOT_DIR = errno.ENOENT
else:
PATH_COMPONENT_NOT_DIR = errno.ENOTDIR
# py.test caches rewritten pycs in __pycache__.
if hasattr(imp, "get_tag"):
PYTEST_TAG = imp.get_tag() + "-PYTEST"
else:
if hasattr(sys, "pypy_version_info"):
impl = "pypy"
elif sys.platform == "java":
impl = "jython"
else:
impl = "cpython"
ver = sys.version_info
PYTEST_TAG = "%s-%s%s-PYTEST" % (impl, ver[0], ver[1])
del ver, impl
PYC_EXT = ".py" + "c" if __debug__ else "o"
PYC_TAIL = "." + PYTEST_TAG + PYC_EXT
REWRITE_NEWLINES = sys.version_info[:2] != (2, 7) and sys.version_info < (3, 2)
class AssertionRewritingHook(object):
"""PEP302 Import hook which rewrites asserts."""
def __init__(self):
self.session = None
self.modules = {}
def set_session(self, session):
self.fnpats = session.config.getini("python_files")
self.session = session
def find_module(self, name, path=None):
if self.session is None:
return None
sess = self.session
state = sess.config._assertstate
state.trace("find_module called for: %s" % name)
names = name.rsplit(".", 1)
lastname = names[-1]
pth = None
if path is not None and len(path) == 1:
pth = path[0]
if pth is None:
try:
fd, fn, desc = imp.find_module(lastname, path)
except ImportError:
return None
if fd is not None:
fd.close()
tp = desc[2]
if tp == imp.PY_COMPILED:
if hasattr(imp, "source_from_cache"):
fn = imp.source_from_cache(fn)
else:
fn = fn[:-1]
elif tp != imp.PY_SOURCE:
# Don't know what this is.
return None
else:
fn = os.path.join(pth, name.rpartition(".")[2] + ".py")
fn_pypath = py.path.local(fn)
# Is this a test file?
if not sess.isinitpath(fn):
# We have to be very careful here because imports in this code can
# trigger a cycle.
self.session = None
try:
for pat in self.fnpats:
if fn_pypath.fnmatch(pat):
state.trace("matched test file %r" % (fn,))
break
else:
return None
finally:
self.session = sess
else:
state.trace("matched test file (was specified on cmdline): %r" %
(fn,))
# The requested module looks like a test file, so rewrite it. This is
# the most magical part of the process: load the source, rewrite the
# asserts, and load the rewritten source. We also cache the rewritten
# module code in a special pyc. We must be aware of the possibility of
# concurrent py.test processes rewriting and loading pycs. To avoid
# tricky race conditions, we maintain the following invariant: The
# cached pyc is always a complete, valid pyc. Operations on it must be
# atomic. POSIX's atomic rename comes in handy.
write = not sys.dont_write_bytecode
cache_dir = os.path.join(fn_pypath.dirname, "__pycache__")
if write:
try:
os.mkdir(cache_dir)
except OSError:
e = sys.exc_info()[1].errno
if e == errno.EEXIST:
# Either the __pycache__ directory already exists (the
# common case) or it's blocked by a non-dir node. In the
# latter case, we'll ignore it in _write_pyc.
pass
elif e == PATH_COMPONENT_NOT_DIR:
# One of the path components was not a directory, likely
# because we're in a zip file.
write = False
elif e == errno.EACCES:
state.trace("read only directory: %r" % fn_pypath.dirname)
write = False
else:
raise
cache_name = fn_pypath.basename[:-3] + PYC_TAIL
pyc = os.path.join(cache_dir, cache_name)
# Notice that even if we're in a read-only directory, I'm going
# to check for a cached pyc. This may not be optimal...
co = _read_pyc(fn_pypath, pyc)
if co is None:
state.trace("rewriting %r" % (fn,))
co = _rewrite_test(state, fn_pypath)
if co is None:
# Probably a SyntaxError in the test.
return None
if write:
_make_rewritten_pyc(state, fn_pypath, pyc, co)
else:
state.trace("found cached rewritten pyc for %r" % (fn,))
self.modules[name] = co, pyc
return self
def load_module(self, name):
co, pyc = self.modules.pop(name)
# I wish I could just call imp.load_compiled here, but __file__ has to
# be set properly. In Python 3.2+, this all would be handled correctly
# by load_compiled.
mod = sys.modules[name] = imp.new_module(name)
try:
mod.__file__ = co.co_filename
# Normally, this attribute is 3.2+.
mod.__cached__ = pyc
py.builtin.exec_(co, mod.__dict__)
except:
del sys.modules[name]
raise
return sys.modules[name]
def _write_pyc(co, source_path, pyc):
# Technically, we don't have to have the same pyc format as
# (C)Python, since these "pycs" should never be seen by builtin
# import. However, there's little reason deviate, and I hope
# sometime to be able to use imp.load_compiled to load them. (See
# the comment in load_module above.)
mtime = int(source_path.mtime())
try:
fp = open(pyc, "wb")
except IOError:
err = sys.exc_info()[1].errno
if err == PATH_COMPONENT_NOT_DIR:
# This happens when we get a EEXIST in find_module creating the
# __pycache__ directory and __pycache__ is by some non-dir node.
return False
raise
try:
fp.write(imp.get_magic())
fp.write(struct.pack("<l", mtime))
marshal.dump(co, fp)
finally:
fp.close()
return True
RN = "\r\n".encode("utf-8")
N = "\n".encode("utf-8")
def _rewrite_test(state, fn):
"""Try to read and rewrite *fn* and return the code object."""
try:
source = fn.read("rb")
except EnvironmentError:
return None
# On Python versions which are not 2.7 and less than or equal to 3.1, the
# parser expects *nix newlines.
if REWRITE_NEWLINES:
source = source.replace(RN, N) + N
try:
tree = ast.parse(source)
except SyntaxError:
# Let this pop up again in the real import.
state.trace("failed to parse: %r" % (fn,))
return None
rewrite_asserts(tree)
try:
co = compile(tree, fn.strpath, "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.
state.trace("failed to compile: %r" % (fn,))
return None
return co
def _make_rewritten_pyc(state, fn, pyc, co):
"""Try to dump rewritten code to *pyc*."""
if sys.platform.startswith("win"):
# Windows grants exclusive access to open files and doesn't have atomic
# rename, so just write into the final file.
_write_pyc(co, fn, pyc)
else:
# When not on windows, assume rename is atomic. Dump the code object
# into a file specific to this process and atomically replace it.
proc_pyc = pyc + "." + str(os.getpid())
if _write_pyc(co, fn, proc_pyc):
os.rename(proc_pyc, pyc)
def _read_pyc(source, pyc):
"""Possibly read a py.test pyc containing rewritten code.
Return rewritten code if successful or None if not.
"""
try:
fp = open(pyc, "rb")
except IOError:
return None
try:
try:
mtime = int(source.mtime())
data = fp.read(8)
except EnvironmentError:
return None
# Check for invalid or out of date pyc file.
if (len(data) != 8 or data[:4] != imp.get_magic() or
struct.unpack("<l", data[4:])[0] != mtime):
return None
co = marshal.load(fp)
if not isinstance(co, types.CodeType):
# That's interesting....
return None
return co
finally:
fp.close()
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(explanations, is_or):
return "(" + (is_or and " or " or " and ").join(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: "%%", # escaped for string formatting
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 or
item.module != "__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 = [mod]
while nodes:
node = nodes.pop()
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.append(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.cond_chain = ()
self.variables = []
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_)
# Clear temporary variables by setting them to None.
if self.variables:
variables = [ast.Name(name, ast.Store())
for name in self.variables]
clear = ast.Assign(variables, ast.Name("None", ast.Load()))
self.statements.append(clear)
# 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):
res_var = self.variable()
expl_list = self.assign(ast.List([], ast.Load()))
app = ast.Attribute(expl_list, "append", ast.Load())
is_or = int(isinstance(boolop.op, ast.Or))
body = save = self.statements
fail_save = self.on_failure
levels = len(boolop.values) - 1
self.push_format_context()
# Process each operand, short-circuting if needed.
for i, v in enumerate(boolop.values):
if i:
fail_inner = []
self.on_failure.append(ast.If(cond, fail_inner, []))
self.on_failure = fail_inner
self.push_format_context()
res, expl = self.visit(v)
body.append(ast.Assign([ast.Name(res_var, ast.Store())], res))
expl_format = self.pop_format_context(ast.Str(expl))
call = ast.Call(app, [expl_format], [], None, None)
self.on_failure.append(ast.Expr(call))
if i < levels:
cond = res
if is_or:
cond = ast.UnaryOp(ast.Not(), cond)
inner = []
self.statements.append(ast.If(cond, inner, []))
self.statements = body = inner
self.statements = save
self.on_failure = fail_save
expl_template = self.helper("format_boolop", expl_list, ast.Num(is_or))
expl = self.pop_format_context(expl_template)
return ast.Name(res_var, ast.Load()), 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.kwargs)
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))