"""Utilities for assertion debugging"""
import pprint
import _pytest._code
import py
try:
from collections import Sequence
except ImportError:
Sequence = list
BuiltinAssertionError = py.builtin.builtins.AssertionError
u = py.builtin._totext
# The _reprcompare attribute on the util module is used by the new assertion
# interpretation code and assertion rewriter to detect this plugin was
# loaded and in turn call the hooks defined here as part of the
# DebugInterpreter.
_reprcompare = None
# the re-encoding is needed for python2 repr
# with non-ascii characters (see issue 877 and 1379)
def ecu(s):
try:
return u(s, 'utf-8', 'replace')
except TypeError:
return s
def format_explanation(explanation):
"""This formats an explanation
Normally all embedded newlines are escaped, however there are
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.
"""
explanation = ecu(explanation)
explanation = _collapse_false(explanation)
lines = _split_explanation(explanation)
result = _format_lines(lines)
return u('\n').join(result)
def _collapse_false(explanation):
"""Collapse expansions of False
So this strips out any "assert False\n{where False = ...\n}"
blocks.
"""
where = 0
while True:
start = where = explanation.find("False\n{False = ", where)
if where == -1:
break
level = 0
prev_c = explanation[start]
for i, c in enumerate(explanation[start:]):
if prev_c + c == "\n{":
level += 1
elif prev_c + c == "\n}":
level -= 1
if not level:
break
prev_c = c
else:
raise AssertionError("unbalanced braces: %r" % (explanation,))
end = start + i
where = end
if explanation[end - 1] == '\n':
explanation = (explanation[:start] + explanation[start+15:end-1] +
explanation[end+1:])
where -= 17
return explanation
def _split_explanation(explanation):
"""Return a list of individual lines in the explanation
This will return a list of lines split on '\n{', '\n}' and '\n~'.
Any other newlines will be escaped and appear in the line as the
literal '\n' characters.
"""
raw_lines = (explanation or u('')).split('\n')
lines = [raw_lines[0]]
for l in raw_lines[1:]:
if l and l[0] in ['{', '}', '~', '>']:
lines.append(l)
else:
lines[-1] += '\\n' + l
return lines
def _format_lines(lines):
"""Format the individual lines
This will replace the '{', '}' and '~' characters of our mini
formatting language with the proper 'where ...', 'and ...' and ' +
...' text, taking care of indentation along the way.
Return a list of formatted lines.
"""
result = lines[:1]
stack = [0]
stackcnt = [0]
for line in lines[1:]:
if line.startswith('{'):
if stackcnt[-1]:
s = u('and ')
else:
s = u('where ')
stack.append(len(result))
stackcnt[-1] += 1
stackcnt.append(0)
result.append(u(' +') + u(' ')*(len(stack)-1) + s + line[1:])
elif line.startswith('}'):
stack.pop()
stackcnt.pop()
result[stack[-1]] += line[1:]
else:
assert line[0] in ['~', '>']
stack[-1] += 1
indent = len(stack) if line.startswith('~') else len(stack) - 1
result.append(u(' ')*indent + line[1:])
assert len(stack) == 1
return result
# Provide basestring in python3
try:
basestring = basestring
except NameError:
basestring = str
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))
summary = u('%s %s %s') % (ecu(left_repr), op, ecu(right_repr))
issequence = lambda x: (isinstance(x, (list, tuple, Sequence)) and
not isinstance(x, basestring))
istext = lambda x: isinstance(x, basestring)
isdict = lambda x: isinstance(x, dict)
isset = lambda x: isinstance(x, (set, frozenset))
def isiterable(obj):
try:
iter(obj)
return not istext(obj)
except TypeError:
return False
verbose = config.getoption('verbose')
explanation = None
try:
if op == '==':
if istext(left) and istext(right):
explanation = _diff_text(left, right, verbose)
else:
if issequence(left) and issequence(right):
explanation = _compare_eq_sequence(left, right, verbose)
elif isset(left) and isset(right):
explanation = _compare_eq_set(left, right, verbose)
elif isdict(left) and isdict(right):
explanation = _compare_eq_dict(left, right, verbose)
if isiterable(left) and isiterable(right):
expl = _compare_eq_iterable(left, right, verbose)
if explanation is not None:
explanation.extend(expl)
else:
explanation = expl
elif op == 'not in':
if istext(left) and istext(right):
explanation = _notin_text(left, right, verbose)
except Exception:
explanation = [
u('(pytest_assertion plugin: representation of details failed. '
'Probably an object has a faulty __repr__.)'),
u(_pytest._code.ExceptionInfo())]
if not explanation:
return None
return [summary] + explanation
def _diff_text(left, right, verbose=False):
"""Return the explanation for the diff between text or bytes
Unless --verbose is used this will skip leading and trailing
characters which are identical to keep the diff minimal.
If the input are bytes they will be safely converted to text.
"""
from difflib import ndiff
explanation = []
if isinstance(left, py.builtin.bytes):
left = u(repr(left)[1:-1]).replace(r'\n', '\n')
if isinstance(right, py.builtin.bytes):
right = u(repr(right)[1:-1]).replace(r'\n', '\n')
if not verbose:
i = 0 # just in case left or right has zero length
for i in range(min(len(left), len(right))):
if left[i] != right[i]:
break
if i > 42:
i -= 10 # Provide some context
explanation = [u('Skipping %s identical leading '
'characters in diff, use -v to show') % i]
left = left[i:]
right = right[i:]
if len(left) == len(right):
for i in range(len(left)):
if left[-i] != right[-i]:
break
if i > 42:
i -= 10 # Provide some context
explanation += [u('Skipping %s identical trailing '
'characters in diff, use -v to show') % i]
left = left[:-i]
right = right[:-i]
explanation += [line.strip('\n')
for line in ndiff(left.splitlines(),
right.splitlines())]
return explanation
def _compare_eq_iterable(left, right, verbose=False):
if not verbose:
return [u('Use -v to get the full diff')]
# dynamic import to speedup pytest
import difflib
try:
left_formatting = pprint.pformat(left).splitlines()
right_formatting = pprint.pformat(right).splitlines()
explanation = [u('Full diff:')]
except Exception:
# hack: PrettyPrinter.pformat() in python 2 fails when formatting items that can't be sorted(), ie, calling
# sorted() on a list would raise. See issue #718.
# As a workaround, the full diff is generated by using the repr() string of each item of each container.
left_formatting = sorted(repr(x) for x in left)
right_formatting = sorted(repr(x) for x in right)
explanation = [u('Full diff (fallback to calling repr on each item):')]
explanation.extend(line.strip() for line in difflib.ndiff(left_formatting, right_formatting))
return explanation
def _compare_eq_sequence(left, right, verbose=False):
explanation = []
for i in range(min(len(left), len(right))):
if left[i] != right[i]:
explanation += [u('At index %s diff: %r != %r')
% (i, left[i], right[i])]
break
if len(left) > len(right):
explanation += [u('Left contains more items, first extra item: %s')
% py.io.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)],)]
return explanation
def _compare_eq_set(left, right, verbose=False):
explanation = []
diff_left = left - right
diff_right = right - left
if diff_left:
explanation.append(u('Extra items in the left set:'))
for item in diff_left:
explanation.append(py.io.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))
return explanation
def _compare_eq_dict(left, right, verbose=False):
explanation = []
common = set(left).intersection(set(right))
same = dict((k, left[k]) for k in common if left[k] == right[k])
if same and not verbose:
explanation += [u('Omitting %s identical items, use -v to show') %
len(same)]
elif same:
explanation += [u('Common items:')]
explanation += pprint.pformat(same).splitlines()
diff = set(k for k in common if left[k] != right[k])
if diff:
explanation += [u('Differing items:')]
for k in diff:
explanation += [py.io.saferepr({k: left[k]}) + ' != ' +
py.io.saferepr({k: right[k]})]
extra_left = set(left) - set(right)
if extra_left:
explanation.append(u('Left contains more items:'))
explanation.extend(pprint.pformat(
dict((k, left[k]) for k in extra_left)).splitlines())
extra_right = set(right) - set(left)
if extra_right:
explanation.append(u('Right contains more items:'))
explanation.extend(pprint.pformat(
dict((k, right[k]) for k in extra_right)).splitlines())
return explanation
def _notin_text(term, text, verbose=False):
index = text.find(term)
head = text[:index]
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)]
for line in diff:
if line.startswith(u('Skipping')):
continue
if line.startswith(u('- ')):
continue
if line.startswith(u('+ ')):
newdiff.append(u(' ') + line[2:])
else:
newdiff.append(line)
return newdiff