285 lines
9.8 KiB
Python
285 lines
9.8 KiB
Python
"""Utilities for assertion debugging"""
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import pprint
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import py
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try:
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from collections import Sequence
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except ImportError:
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Sequence = list
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BuiltinAssertionError = py.builtin.builtins.AssertionError
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u = py.builtin._totext
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# The _reprcompare attribute on the util module is used by the new assertion
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# interpretation code and assertion rewriter to detect this plugin was
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# loaded and in turn call the hooks defined here as part of the
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# DebugInterpreter.
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_reprcompare = None
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def format_explanation(explanation):
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"""This formats an explanation
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Normally all embedded newlines are escaped, however there are
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three exceptions: \n{, \n} and \n~. The first two are intended
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cover nested explanations, see function and attribute explanations
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for examples (.visit_Call(), visit_Attribute()). The last one is
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for when one explanation needs to span multiple lines, e.g. when
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displaying diffs.
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"""
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explanation = _collapse_false(explanation)
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lines = _split_explanation(explanation)
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result = _format_lines(lines)
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return u('\n').join(result)
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def _collapse_false(explanation):
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"""Collapse expansions of False
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So this strips out any "assert False\n{where False = ...\n}"
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blocks.
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"""
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where = 0
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while True:
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start = where = explanation.find("False\n{False = ", where)
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if where == -1:
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break
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level = 0
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for i, c in enumerate(explanation[start:]):
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if c == "{":
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level += 1
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elif c == "}":
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level -= 1
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if not level:
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break
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else:
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raise AssertionError("unbalanced braces: %r" % (explanation,))
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end = start + i
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where = end
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if explanation[end - 1] == '\n':
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explanation = (explanation[:start] + explanation[start+15:end-1] +
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explanation[end+1:])
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where -= 17
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return explanation
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def _split_explanation(explanation):
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"""Return a list of individual lines in the explanation
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This will return a list of lines split on '\n{', '\n}' and '\n~'.
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Any other newlines will be escaped and appear in the line as the
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literal '\n' characters.
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"""
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raw_lines = (explanation or u('')).split('\n')
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lines = [raw_lines[0]]
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for l in raw_lines[1:]:
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if l and l[0] in ['{', '}', '~', '>']:
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lines.append(l)
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else:
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lines[-1] += '\\n' + l
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return lines
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def _format_lines(lines):
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"""Format the individual lines
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This will replace the '{', '}' and '~' characters of our mini
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formatting language with the proper 'where ...', 'and ...' and ' +
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...' text, taking care of indentation along the way.
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Return a list of formatted lines.
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"""
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result = lines[:1]
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stack = [0]
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stackcnt = [0]
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for line in lines[1:]:
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if line.startswith('{'):
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if stackcnt[-1]:
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s = u('and ')
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else:
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s = u('where ')
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stack.append(len(result))
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stackcnt[-1] += 1
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stackcnt.append(0)
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result.append(u(' +') + u(' ')*(len(stack)-1) + s + line[1:])
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elif line.startswith('}'):
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stack.pop()
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stackcnt.pop()
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result[stack[-1]] += line[1:]
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else:
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assert line[0] in ['~', '>']
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stack[-1] += 1
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indent = len(stack) if line.startswith('~') else len(stack) - 1
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result.append(u(' ')*indent + line[1:])
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assert len(stack) == 1
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return result
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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 assertrepr_compare(config, 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 = u('%s %s %s') % (left_repr, op, right_repr)
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issequence = lambda x: (isinstance(x, (list, tuple, Sequence))
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and not isinstance(x, basestring))
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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, frozenset))
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verbose = config.getoption('verbose')
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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, verbose)
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elif issequence(left) and issequence(right):
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explanation = _compare_eq_sequence(left, right, verbose)
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elif isset(left) and isset(right):
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explanation = _compare_eq_set(left, right, verbose)
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elif isdict(left) and isdict(right):
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explanation = _compare_eq_dict(left, right, verbose)
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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, verbose)
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except Exception:
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explanation = [
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u('(pytest_assertion plugin: representation of details failed. '
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'Probably an object has a faulty __repr__.)'),
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u(py.code.ExceptionInfo())]
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if not explanation:
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return None
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return [summary] + explanation
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def _diff_text(left, right, verbose=False):
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"""Return the explanation for the diff between text or bytes
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Unless --verbose is used this will skip leading and trailing
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characters which are identical to keep the diff minimal.
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If the input are bytes they will be safely converted to text.
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"""
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from difflib import ndiff
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explanation = []
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if isinstance(left, py.builtin.bytes):
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left = u(repr(left)[1:-1]).replace(r'\n', '\n')
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if isinstance(right, py.builtin.bytes):
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right = u(repr(right)[1:-1]).replace(r'\n', '\n')
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if not verbose:
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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 = [u('Skipping %s identical leading '
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'characters in diff, use -v to show') % 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 += [u('Skipping %s identical trailing '
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'characters in diff, use -v to show') % 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 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, verbose=False):
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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 += [u('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 += [u('Left contains more items, first extra item: %s')
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% py.io.saferepr(left[len(right)],)]
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elif len(left) < len(right):
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explanation += [
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u('Right contains more items, first extra item: %s') %
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py.io.saferepr(right[len(left)],)]
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return explanation # + _diff_text(pprint.pformat(left),
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# pprint.pformat(right))
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def _compare_eq_set(left, right, verbose=False):
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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(u('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(u('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 _compare_eq_dict(left, right, verbose=False):
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explanation = []
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common = set(left).intersection(set(right))
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same = dict((k, left[k]) for k in common if left[k] == right[k])
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if same and not verbose:
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explanation += [u('Omitting %s identical items, use -v to show') %
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len(same)]
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elif same:
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explanation += [u('Common items:')]
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explanation += pprint.pformat(same).splitlines()
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diff = set(k for k in common if left[k] != right[k])
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if diff:
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explanation += [u('Differing items:')]
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for k in diff:
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explanation += [py.io.saferepr({k: left[k]}) + ' != ' +
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py.io.saferepr({k: right[k]})]
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extra_left = set(left) - set(right)
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if extra_left:
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explanation.append(u('Left contains more items:'))
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explanation.extend(pprint.pformat(
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dict((k, left[k]) for k in extra_left)).splitlines())
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extra_right = set(right) - set(left)
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if extra_right:
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explanation.append(u('Right contains more items:'))
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explanation.extend(pprint.pformat(
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dict((k, right[k]) for k in extra_right)).splitlines())
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return explanation
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def _notin_text(term, text, verbose=False):
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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, verbose)
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newdiff = [u('%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(u('Skipping')):
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continue
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if line.startswith(u('- ')):
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continue
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if line.startswith(u('+ ')):
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newdiff.append(u(' ') + line[2:])
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else:
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newdiff.append(line)
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return newdiff
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