"""Utilities for assertion debugging""" from __future__ import absolute_import, division, print_function u = str # 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 # Provide basestring in python3 try: basestring = basestring except NameError: basestring = str def saferepr(obj, maxsize=None): s = repr(obj) if maxsize is not None: s = s[:maxsize] return s def callbinrepr(op, left, right): new_expl = assertrepr_compare(op, left, right) new_expl = [line.replace("\n", "\\n") for line in new_expl] res = "\n~".join(new_expl) res = res.replace("%", "%%") return res def assertrepr_compare(op, left, right, verbose=False): """Return specialised explanations for some operators/operands""" width = 80 - 15 - len(op) - 2 # 15 chars indentation, 1 space around op left_repr = saferepr(left, maxsize=int(width // 2)) right_repr = saferepr(right, maxsize=width - len(left_repr)) summary = u('%s %s %s') % (left_repr, op, right_repr) def issequence(x): return hasattr(x, '__iter__') and not isinstance(x, basestring) def istext(x): return isinstance(x, basestring) def isdict(x): return isinstance(x, dict) def isset(x): return isinstance(x, (set, frozenset)) def isiterable(obj): try: iter(obj) return not istext(obj) except TypeError: return False 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 as err: explanation = [ '(pytest assertion: representation of details failed. ' 'Probably an object has a faulty __repr__.)', str(err)] 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 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 = ['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 += ['Skipping %s identical trailing ' 'characters in diff, use -v to show' % i] left = left[:-i] right = right[:-i] keepends = True explanation += [line.strip('\n') for line in ndiff(left.splitlines(keepends), right.splitlines(keepends))] return explanation def _compare_eq_iterable(left, right, verbose=False): if not verbose: return ['Use -v to get the full diff'] # dynamic import to speedup pytest import difflib, pprint try: left_formatting = pprint.pformat(left).splitlines() right_formatting = pprint.pformat(right).splitlines() explanation = ['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 = ['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') % saferepr(left[len(right)],)] elif len(left) < len(right): explanation += [ u('Right contains more items, first extra item: %s') % 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(saferepr(item)) if diff_right: explanation.append(u('Extra items in the right set:')) for item in diff_right: explanation.append(saferepr(item)) return explanation def _compare_eq_dict(left, right, verbose=False): import pprint explanation = [] common = set(left).intersection(set(right)) same = dict((k, left[k]) for k in common if left[k] == right[k]) if same and verbose < 2: explanation += [u('Omitting %s identical items, use -vv 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 += [saferepr({k: left[k]}) + ' != ' + 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:') % 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