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+# Copyright (c) 2009 Jonathan M. Lange. See LICENSE for details.
+
+"""Matchers, a way to express complex assertions outside the testcase.
+
+Inspired by 'hamcrest'.
+
+Matcher provides the abstract API that all matchers need to implement.
+
+Bundled matchers are listed in __all__: a list can be obtained by running
+$ python -c 'import testtools.matchers; print testtools.matchers.__all__'
+"""
+
+__metaclass__ = type
+__all__ = [
+ 'DocTestMatches',
+ 'Equals',
+ 'MatchesAny',
+ ]
+
+import doctest
+
+
+class Matcher:
+ """A pattern matcher.
+
+ A Matcher must implement match and __str__ to be used by
+ testtools.TestCase.assertThat. Matcher.match(thing) returns None when
+ thing is completely matched, and a Mismatch object otherwise.
+
+ Matchers can be useful outside of test cases, as they are simply a
+ pattern matching language expressed as objects.
+
+ testtools.matchers is inspired by hamcrest, but is pythonic rather than
+ a Java transcription.
+ """
+
+ def match(self, something):
+ """Return None if this matcher matches something, a Mismatch otherwise.
+ """
+ raise NotImplementedError(self.match)
+
+ def __str__(self):
+ """Get a sensible human representation of the matcher.
+
+ This should include the parameters given to the matcher and any
+ state that would affect the matches operation.
+ """
+ raise NotImplementedError(self.__str__)
+
+
+class Mismatch:
+ """An object describing a mismatch detected by a Matcher."""
+
+ def describe(self):
+ """Describe the mismatch.
+
+ This should be either a human-readable string or castable to a string.
+ """
+ raise NotImplementedError(self.describe_difference)
+
+
+class DocTestMatches:
+ """See if a string matches a doctest example."""
+
+ def __init__(self, example, flags=0):
+ """Create a DocTestMatches to match example.
+
+ :param example: The example to match e.g. 'foo bar baz'
+ :param flags: doctest comparison flags to match on. e.g.
+ doctest.ELLIPSIS.
+ """
+ if not example.endswith('\n'):
+ example += '\n'
+ self.want = example # required variable name by doctest.
+ self.flags = flags
+ self._checker = doctest.OutputChecker()
+
+ def __str__(self):
+ if self.flags:
+ flagstr = ", flags=%d" % self.flags
+ else:
+ flagstr = ""
+ return 'DocTestMatches(%r%s)' % (self.want, flagstr)
+
+ def _with_nl(self, actual):
+ result = str(actual)
+ if not result.endswith('\n'):
+ result += '\n'
+ return result
+
+ def match(self, actual):
+ with_nl = self._with_nl(actual)
+ if self._checker.check_output(self.want, with_nl, self.flags):
+ return None
+ return DocTestMismatch(self, with_nl)
+
+ def _describe_difference(self, with_nl):
+ return self._checker.output_difference(self, with_nl, self.flags)
+
+
+class DocTestMismatch:
+ """Mismatch object for DocTestMatches."""
+
+ def __init__(self, matcher, with_nl):
+ self.matcher = matcher
+ self.with_nl = with_nl
+
+ def describe(self):
+ return self.matcher._describe_difference(self.with_nl)
+
+
+class Equals:
+ """Matches if the items are equal."""
+
+ def __init__(self, expected):
+ self.expected = expected
+
+ def match(self, other):
+ if self.expected == other:
+ return None
+ return EqualsMismatch(self.expected, other)
+
+ def __str__(self):
+ return "Equals(%r)" % self.expected
+
+
+class EqualsMismatch:
+ """Two things differed."""
+
+ def __init__(self, expected, other):
+ self.expected = expected
+ self.other = other
+
+ def describe(self):
+ return "%r != %r" % (self.expected, self.other)
+
+
+class MatchesAny:
+ """Matches if any of the matchers it is created with match."""
+
+ def __init__(self, *matchers):
+ self.matchers = matchers
+
+ def match(self, matchee):
+ results = []
+ for matcher in self.matchers:
+ mismatch = matcher.match(matchee)
+ if mismatch is None:
+ return None
+ results.append(mismatch)
+ return MismatchesAll(results)
+
+ def __str__(self):
+ return "MatchesAny(%s)" % ', '.join([
+ str(matcher) for matcher in self.matchers])
+
+
+class MismatchesAll:
+ """A mismatch with many child mismatches."""
+
+ def __init__(self, mismatches):
+ self.mismatches = mismatches
+
+ def describe(self):
+ descriptions = ["Differences: ["]
+ for mismatch in self.mismatches:
+ descriptions.append(mismatch.describe())
+ descriptions.append("]\n")
+ return '\n'.join(descriptions)