Merge pull request #4657 from asottile/py_io_saferepr

copy saferepr from pylib

.pre-commit-config.yaml

@@ -54,5 +54,5 @@ repos:
     -   id: py-deprecated
         name: py library is deprecated
         language: pygrep
-        entry: '\bpy\.(builtin\.|code\.|std\.)'
+        entry: '\bpy\.(builtin\.|code\.|std\.|io\.saferepr)'
         types: [python]

changelog/4657.trivial.rst

@@ -0,0 +1 @@
+Copy saferepr from pylib

setup.cfg

@@ -36,10 +36,11 @@ platforms = unix, linux, osx, cygwin, win32
 zip_safe = no
 packages =
     _pytest
-    _pytest.assertion
     _pytest._code
-    _pytest.mark
+    _pytest._io
+    _pytest.assertion
     _pytest.config
+    _pytest.mark
 
 py_modules = pytest
 python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*

src/_pytest/_code/code.py

@@ -18,6 +18,7 @@ import six
 from six import text_type
 
 import _pytest
+from _pytest._io.saferepr import saferepr
 from _pytest.compat import _PY2
 from _pytest.compat import _PY3
 from _pytest.compat import PY35
@@ -144,7 +145,7 @@ class Frame(object):
     def repr(self, object):
         """ return a 'safe' (non-recursive, one-line) string repr for 'object'
         """
-        return py.io.saferepr(object)
+        return saferepr(object)
 
     def is_true(self, object):
         return object
@@ -423,7 +424,7 @@ class ExceptionInfo(object):
         if exprinfo is None and isinstance(tup[1], AssertionError):
             exprinfo = getattr(tup[1], "msg", None)
             if exprinfo is None:
-                exprinfo = py.io.saferepr(tup[1])
+                exprinfo = saferepr(tup[1])
             if exprinfo and exprinfo.startswith(cls._assert_start_repr):
                 _striptext = "AssertionError: "
 
@@ -620,7 +621,7 @@ class FormattedExcinfo(object):
         return source
 
     def _saferepr(self, obj):
-        return py.io.saferepr(obj)
+        return saferepr(obj)
 
     def repr_args(self, entry):
         if self.funcargs:

src/_pytest/_io/saferepr.py

@@ -0,0 +1,72 @@
+import sys
+
+from six.moves import reprlib
+
+
+class SafeRepr(reprlib.Repr):
+    """subclass of repr.Repr that limits the resulting size of repr()
+    and includes information on exceptions raised during the call.
+    """
+
+    def repr(self, x):
+        return self._callhelper(reprlib.Repr.repr, self, x)
+
+    def repr_unicode(self, x, level):
+        # Strictly speaking wrong on narrow builds
+        def repr(u):
+            if "'" not in u:
+                return u"'%s'" % u
+            elif '"' not in u:
+                return u'"%s"' % u
+            else:
+                return u"'%s'" % u.replace("'", r"\'")
+
+        s = repr(x[: self.maxstring])
+        if len(s) > self.maxstring:
+            i = max(0, (self.maxstring - 3) // 2)
+            j = max(0, self.maxstring - 3 - i)
+            s = repr(x[:i] + x[len(x) - j :])
+            s = s[:i] + "..." + s[len(s) - j :]
+        return s
+
+    def repr_instance(self, x, level):
+        return self._callhelper(repr, x)
+
+    def _callhelper(self, call, x, *args):
+        try:
+            # Try the vanilla repr and make sure that the result is a string
+            s = call(x, *args)
+        except Exception:
+            cls, e, tb = sys.exc_info()
+            exc_name = getattr(cls, "__name__", "unknown")
+            try:
+                exc_info = str(e)
+            except Exception:
+                exc_info = "unknown"
+            return '<[%s("%s") raised in repr()] %s object at 0x%x>' % (
+                exc_name,
+                exc_info,
+                x.__class__.__name__,
+                id(x),
+            )
+        else:
+            if len(s) > self.maxsize:
+                i = max(0, (self.maxsize - 3) // 2)
+                j = max(0, self.maxsize - 3 - i)
+                s = s[:i] + "..." + s[len(s) - j :]
+            return s
+
+
+def saferepr(obj, maxsize=240):
+    """return a size-limited safe repr-string for the given object.
+    Failing __repr__ functions of user instances will be represented
+    with a short exception info and 'saferepr' generally takes
+    care to never raise exceptions itself.  This function is a wrapper
+    around the Repr/reprlib functionality of the standard 2.6 lib.
+    """
+    # review exception handling
+    srepr = SafeRepr()
+    srepr.maxstring = maxsize
+    srepr.maxsize = maxsize
+    srepr.maxother = 160
+    return srepr.repr(obj)

src/_pytest/assertion/rewrite.py

@@ -19,6 +19,7 @@ import atomicwrites
 import py
 import six
 
+from _pytest._io.saferepr import saferepr
 from _pytest.assertion import util
 from _pytest.compat import spec_from_file_location
 from _pytest.pathlib import fnmatch_ex
@@ -484,7 +485,7 @@ def _saferepr(obj):
     JSON reprs.
 
     """
-    r = py.io.saferepr(obj)
+    r = saferepr(obj)
     # only occurs in python2.x, repr must return text in python3+
     if isinstance(r, bytes):
         # Represent unprintable bytes as `\x##`
@@ -503,7 +504,7 @@ def _format_assertmsg(obj):
 
     For strings this simply replaces newlines with '\n~' so that
     util.format_explanation() will preserve them instead of escaping
-    newlines.  For other objects py.io.saferepr() is used first.
+    newlines.  For other objects saferepr() is used first.
 
     """
     # reprlib appears to have a bug which means that if a string
@@ -512,7 +513,7 @@ def _format_assertmsg(obj):
     # However in either case we want to preserve the newline.
     replaces = [(u"\n", u"\n~"), (u"%", u"%%")]
     if not isinstance(obj, six.string_types):
-        obj = py.io.saferepr(obj)
+        obj = saferepr(obj)
         replaces.append((u"\\n", u"\n~"))
 
     if isinstance(obj, bytes):
@@ -753,7 +754,7 @@ class AssertionRewriter(ast.NodeVisitor):
         return ast.Name(name, ast.Load())
 
     def display(self, expr):
-        """Call py.io.saferepr on the expression."""
+        """Call saferepr on the expression."""
         return self.helper("saferepr", expr)
 
     def helper(self, name, *args):

src/_pytest/assertion/util.py

@@ -5,11 +5,11 @@ from __future__ import print_function
 
 import pprint
 
-import py
 import six
 
 import _pytest._code
 from ..compat import Sequence
+from _pytest._io.saferepr import saferepr
 
 # The _reprcompare attribute on the util module is used by the new assertion
 # interpretation code and assertion rewriter to detect this plugin was
@@ -105,8 +105,8 @@ except NameError:
 def assertrepr_compare(config, 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))
-    right_repr = py.io.saferepr(right, maxsize=width - len(left_repr))
+    left_repr = saferepr(left, maxsize=int(width // 2))
+    right_repr = saferepr(right, maxsize=width - len(left_repr))
 
     summary = u"%s %s %s" % (ecu(left_repr), op, ecu(right_repr))
 
@@ -282,12 +282,12 @@ def _compare_eq_sequence(left, right, verbose=False):
     if len(left) > len(right):
         explanation += [
             u"Left contains more items, first extra item: %s"
-            % py.io.saferepr(left[len(right)])
+            % saferepr(left[len(right)])
         ]
     elif len(left) < len(right):
         explanation += [
             u"Right contains more items, first extra item: %s"
-            % py.io.saferepr(right[len(left)])
+            % saferepr(right[len(left)])
         ]
     return explanation
 
@@ -299,11 +299,11 @@ def _compare_eq_set(left, right, verbose=False):
     if diff_left:
         explanation.append(u"Extra items in the left set:")
         for item in diff_left:
-            explanation.append(py.io.saferepr(item))
+            explanation.append(saferepr(item))
     if diff_right:
         explanation.append(u"Extra items in the right set:")
         for item in diff_right:
-            explanation.append(py.io.saferepr(item))
+            explanation.append(saferepr(item))
     return explanation
 
 
@@ -320,9 +320,7 @@ def _compare_eq_dict(left, right, verbose=False):
     if diff:
         explanation += [u"Differing items:"]
         for k in diff:
-            explanation += [
-                py.io.saferepr({k: left[k]}) + " != " + py.io.saferepr({k: right[k]})
-            ]
+            explanation += [saferepr({k: left[k]}) + " != " + saferepr({k: right[k]})]
     extra_left = set(left) - set(right)
     if extra_left:
         explanation.append(u"Left contains more items:")
@@ -376,7 +374,7 @@ def _notin_text(term, text, verbose=False):
     tail = text[index + len(term) :]
     correct_text = head + tail
     diff = _diff_text(correct_text, text, verbose)
-    newdiff = [u"%s is contained here:" % py.io.saferepr(term, maxsize=42)]
+    newdiff = [u"%s is contained here:" % saferepr(term, maxsize=42)]
     for line in diff:
         if line.startswith(u"Skipping"):
             continue

src/_pytest/compat.py

@@ -17,6 +17,7 @@ import six
 from six import text_type
 
 import _pytest
+from _pytest._io.saferepr import saferepr
 from _pytest.outcomes import fail
 from _pytest.outcomes import TEST_OUTCOME
 
@@ -294,7 +295,7 @@ def get_real_func(obj):
     else:
         raise ValueError(
             ("could not find real function of {start}\nstopped at {current}").format(
-                start=py.io.saferepr(start_obj), current=py.io.saferepr(obj)
+                start=saferepr(start_obj), current=saferepr(obj)
             )
         )
     if isinstance(obj, functools.partial):

src/_pytest/pytester.py

@@ -20,6 +20,7 @@ import six
 
 import pytest
 from _pytest._code import Source
+from _pytest._io.saferepr import saferepr
 from _pytest.assertion.rewrite import AssertionRewritingHook
 from _pytest.capture import MultiCapture
 from _pytest.capture import SysCapture
@@ -1225,9 +1226,7 @@ def getdecoded(out):
     try:
         return out.decode("utf-8")
     except UnicodeDecodeError:
-        return "INTERNAL not-utf8-decodeable, truncated string:\n%s" % (
-            py.io.saferepr(out),
-        )
+        return "INTERNAL not-utf8-decodeable, truncated string:\n%s" % (saferepr(out),)
 
 
 class LineComp(object):

testing/io/test_saferepr.py

@@ -0,0 +1,66 @@
+# -*- coding: utf-8 -*-
+from _pytest._io.saferepr import saferepr
+
+
+def test_simple_repr():
+    assert saferepr(1) == "1"
+    assert saferepr(None) == "None"
+
+
+def test_maxsize():
+    s = saferepr("x" * 50, maxsize=25)
+    assert len(s) == 25
+    expected = repr("x" * 10 + "..." + "x" * 10)
+    assert s == expected
+
+
+def test_maxsize_error_on_instance():
+    class A:
+        def __repr__():
+            raise ValueError("...")
+
+    s = saferepr(("*" * 50, A()), maxsize=25)
+    assert len(s) == 25
+    assert s[0] == "(" and s[-1] == ")"
+
+
+def test_exceptions():
+    class BrokenRepr:
+        def __init__(self, ex):
+            self.ex = ex
+
+        def __repr__(self):
+            raise self.ex
+
+    class BrokenReprException(Exception):
+        __str__ = None
+        __repr__ = None
+
+    assert "Exception" in saferepr(BrokenRepr(Exception("broken")))
+    s = saferepr(BrokenReprException("really broken"))
+    assert "TypeError" in s
+    assert "TypeError" in saferepr(BrokenRepr("string"))
+
+    s2 = saferepr(BrokenRepr(BrokenReprException("omg even worse")))
+    assert "NameError" not in s2
+    assert "unknown" in s2
+
+
+def test_big_repr():
+    from _pytest._io.saferepr import SafeRepr
+
+    assert len(saferepr(range(1000))) <= len("[" + SafeRepr().maxlist * "1000" + "]")
+
+
+def test_repr_on_newstyle():
+    class Function(object):
+        def __repr__(self):
+            return "<%s>" % (self.name)
+
+    assert saferepr(Function())
+
+
+def test_unicode():
+    val = u"£€"
+    reprval = u"'£€'"
+    assert saferepr(val) == reprval