237 lines
7.8 KiB
Python
237 lines
7.8 KiB
Python
"""
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support for presented detailed information in failing assertions.
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"""
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import py
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import imp
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import marshal
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import struct
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import sys
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from _pytest.monkeypatch import monkeypatch
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try:
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from _pytest.assertrewrite import rewrite_asserts
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except ImportError:
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rewrite_asserts = None
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else:
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import ast
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def pytest_addoption(parser):
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group = parser.getgroup("debugconfig")
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group._addoption('--no-assert', action="store_true", default=False,
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dest="noassert",
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help="disable python assert expression reinterpretation."),
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def pytest_configure(config):
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global rewrite_asserts
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# The _reprcompare attribute on the py.code module is used by
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# py._code._assertionnew to detect this plugin was loaded and in
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# turn call the hooks defined here as part of the
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# DebugInterpreter.
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m = monkeypatch()
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config._cleanup.append(m.undo)
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warn_about_missing_assertion()
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if not config.getvalue("noassert") and not config.getvalue("nomagic"):
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def callbinrepr(op, left, right):
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hook_result = config.hook.pytest_assertrepr_compare(
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config=config, op=op, left=left, right=right)
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for new_expl in hook_result:
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if new_expl:
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return '\n~'.join(new_expl)
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m.setattr(py.builtin.builtins,
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'AssertionError', py.code._AssertionError)
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m.setattr(py.code, '_reprcompare', callbinrepr)
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else:
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rewrite_asserts = None
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def _write_pyc(co, source_path):
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if hasattr(imp, "cache_from_source"):
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# Handle PEP 3147 pycs.
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pyc = py.path(imp.cache_from_source(source_math))
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pyc.dirname.ensure(dir=True)
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else:
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pyc = source_path + "c"
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mtime = int(source_path.mtime())
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fp = pyc.open("wb")
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try:
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fp.write(imp.get_magic())
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fp.write(struct.pack("<l", mtime))
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marshal.dump(co, fp)
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finally:
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fp.close()
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return pyc
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def pytest_pycollect_before_module_import(mod):
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if rewrite_asserts is None:
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return
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# Some deep magic: load the source, rewrite the asserts, and write a
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# fake pyc, so that it'll be loaded further down this function.
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source = mod.fspath.read()
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try:
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tree = ast.parse(source)
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except SyntaxError:
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# Let this pop up again in the real import.
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return
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rewrite_asserts(tree)
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try:
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co = compile(tree, str(mod.fspath), "exec")
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except SyntaxError:
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# It's possible that this error is from some bug in the assertion
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# rewriting, but I don't know of a fast way to tell.
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return
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mod._pyc = _write_pyc(co, mod.fspath)
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def pytest_pycollect_after_module_import(mod):
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if rewrite_asserts is None or not hasattr(mod, "_pyc"):
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return
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# Remove our tweaked pyc to avoid subtle bugs.
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try:
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mod._pyc.remove()
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except py.error.ENOENT:
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pass
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def warn_about_missing_assertion():
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try:
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assert False
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except AssertionError:
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pass
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else:
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sys.stderr.write("WARNING: failing tests may report as passing because "
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"assertions are turned off! (are you using python -O?)\n")
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# Provide basestring in python3
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try:
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basestring = basestring
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except NameError:
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basestring = str
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def pytest_assertrepr_compare(op, left, right):
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"""return specialised explanations for some operators/operands"""
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width = 80 - 15 - len(op) - 2 # 15 chars indentation, 1 space around op
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left_repr = py.io.saferepr(left, maxsize=int(width/2))
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right_repr = py.io.saferepr(right, maxsize=width-len(left_repr))
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summary = '%s %s %s' % (left_repr, op, right_repr)
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issequence = lambda x: isinstance(x, (list, tuple))
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istext = lambda x: isinstance(x, basestring)
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isdict = lambda x: isinstance(x, dict)
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isset = lambda x: isinstance(x, set)
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explanation = None
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try:
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if op == '==':
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if istext(left) and istext(right):
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explanation = _diff_text(left, right)
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elif issequence(left) and issequence(right):
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explanation = _compare_eq_sequence(left, right)
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elif isset(left) and isset(right):
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explanation = _compare_eq_set(left, right)
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elif isdict(left) and isdict(right):
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explanation = _diff_text(py.std.pprint.pformat(left),
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py.std.pprint.pformat(right))
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elif op == 'not in':
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if istext(left) and istext(right):
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explanation = _notin_text(left, right)
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except py.builtin._sysex:
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raise
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except:
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excinfo = py.code.ExceptionInfo()
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explanation = ['(pytest_assertion plugin: representation of '
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'details failed. Probably an object has a faulty __repr__.)',
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str(excinfo)
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]
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if not explanation:
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return None
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# Don't include pageloads of data, should be configurable
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if len(''.join(explanation)) > 80*8:
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explanation = ['Detailed information too verbose, truncated']
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return [summary] + explanation
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def _diff_text(left, right):
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"""Return the explanation for the diff between text
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This will skip leading and trailing characters which are
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identical to keep the diff minimal.
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"""
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explanation = []
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i = 0 # just in case left or right has zero length
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for i in range(min(len(left), len(right))):
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if left[i] != right[i]:
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break
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if i > 42:
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i -= 10 # Provide some context
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explanation = ['Skipping %s identical '
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'leading characters in diff' % i]
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left = left[i:]
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right = right[i:]
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if len(left) == len(right):
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for i in range(len(left)):
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if left[-i] != right[-i]:
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break
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if i > 42:
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i -= 10 # Provide some context
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explanation += ['Skipping %s identical '
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'trailing characters in diff' % i]
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left = left[:-i]
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right = right[:-i]
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explanation += [line.strip('\n')
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for line in py.std.difflib.ndiff(left.splitlines(),
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right.splitlines())]
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return explanation
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def _compare_eq_sequence(left, right):
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explanation = []
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for i in range(min(len(left), len(right))):
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if left[i] != right[i]:
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explanation += ['At index %s diff: %r != %r' %
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(i, left[i], right[i])]
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break
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if len(left) > len(right):
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explanation += ['Left contains more items, '
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'first extra item: %s' % py.io.saferepr(left[len(right)],)]
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elif len(left) < len(right):
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explanation += ['Right contains more items, '
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'first extra item: %s' % py.io.saferepr(right[len(left)],)]
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return explanation # + _diff_text(py.std.pprint.pformat(left),
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# py.std.pprint.pformat(right))
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def _compare_eq_set(left, right):
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explanation = []
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diff_left = left - right
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diff_right = right - left
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if diff_left:
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explanation.append('Extra items in the left set:')
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for item in diff_left:
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explanation.append(py.io.saferepr(item))
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if diff_right:
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explanation.append('Extra items in the right set:')
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for item in diff_right:
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explanation.append(py.io.saferepr(item))
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return explanation
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def _notin_text(term, text):
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index = text.find(term)
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head = text[:index]
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tail = text[index+len(term):]
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correct_text = head + tail
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diff = _diff_text(correct_text, text)
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newdiff = ['%s is contained here:' % py.io.saferepr(term, maxsize=42)]
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for line in diff:
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if line.startswith('Skipping'):
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continue
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if line.startswith('- '):
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continue
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if line.startswith('+ '):
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newdiff.append(' ' + line[2:])
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else:
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newdiff.append(line)
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return newdiff
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