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Diffstat (limited to 'python/pytest/_pytest/assertion/util.py')
| -rw-r--r-- | python/pytest/_pytest/assertion/util.py | 332 |
1 files changed, 332 insertions, 0 deletions
diff --git a/python/pytest/_pytest/assertion/util.py b/python/pytest/_pytest/assertion/util.py new file mode 100644 index 000000000..f2f23efea --- /dev/null +++ b/python/pytest/_pytest/assertion/util.py @@ -0,0 +1,332 @@ +"""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 |