ExpectedException now more useful.

NEWS

@@ -39,6 +39,10 @@ Improvements
 * Correctly display non-ASCII unicode output on terminals that claim to have a
   unicode encoding. (Martin [gz], #804122)
 
+* ``ExpectedException`` now matches any exception of the given type by
+  default, and also allows specifying a ``Matcher`` rather than a mere regular
+  expression. (Jonathan Lange, #791889)
+
 * ``FixtureSuite`` added, allows test suites to run with a given fixture.
   (Jonathan Lange)
 

doc/for-test-authors.rst

@@ -160,9 +160,10 @@ particular errors.  ``ExpectedException`` does just that.  For example::
           silly.square('orange')
 
 The first argument to ``ExpectedException`` is the type of exception you
-expect to see raised.  The second argument is an optional regular expression,
-if provided, the ``str()`` of the raised exception must match the regular
-expression.
+expect to see raised.  The second argument is optional, and can be either a
+regular expression or a matcher. If it is a regular expression, the ``str()``
+of the raised exception must match the regular expression. If it is a matcher,
+then the raised exception object must match it.
 
 
 assertIn, assertNotIn

testtools/matchers.py

@@ -421,7 +421,7 @@ class MatchesException(Matcher):
         Matcher.__init__(self)
         self.expected = exception
         if istext(value_re):
-            value_re = AfterPreproccessing(str, MatchesRegex(value_re))
+            value_re = AfterPreproccessing(str, MatchesRegex(value_re), False)
         self.value_re = value_re
         self._is_instance = type(self.expected) not in classtypes()
 
@@ -824,9 +824,19 @@ class AfterPreprocessing(object):
           return AfterPreprocessing(_read, Equals(content))
     """
 
-    def __init__(self, preprocessor, matcher):
+    def __init__(self, preprocessor, matcher, annotate=True):
+        """Create an AfterPreprocessing matcher.
+
+        :param preprocessor: A function called with the matchee before
+            matching.
+        :param matcher: What to match the preprocessed matchee against.
+        :param annotate: Whether or not to annotate the matcher with
+            something explaining how we transformed the matchee. Defaults
+            to True.
+        """
         self.preprocessor = preprocessor
         self.matcher = matcher
+        self.annotate = annotate
 
     def _str_preprocessor(self):
         if isinstance(self.preprocessor, types.FunctionType):
@@ -839,9 +849,13 @@ class AfterPreprocessing(object):
 
     def match(self, value):
         after = self.preprocessor(value)
-        return Annotate(
-            "after %s on %r" % (self._str_preprocessor(), value),
-            self.matcher).match(after)
+        if self.annotate:
+            matcher = Annotate(
+                "after %s on %r" % (self._str_preprocessor(), value),
+                self.matcher)
+        else:
+            matcher = self.matcher
+        return matcher.match(after)
 
 # This is the old, deprecated. spelling of the name, kept for backwards
 # compatibility.

testtools/testcase.py

@@ -16,7 +16,6 @@ __all__ = [
 
 import copy
 import itertools
-import re
 import sys
 import types
 import unittest
@@ -29,6 +28,7 @@ from testtools.compat import advance_iterator
 from testtools.matchers import (
     Annotate,
     Equals,
+    MatchesException,
     Is,
     Not,
     )
@@ -754,7 +754,7 @@ class ExpectedException:
     exception is raised, an AssertionError will be raised.
     """
 
-    def __init__(self, exc_type, value_re):
+    def __init__(self, exc_type, value_re=None):
         """Construct an `ExpectedException`.
 
         :param exc_type: The type of exception to expect.
@@ -772,9 +772,11 @@ class ExpectedException:
             raise AssertionError('%s not raised.' % self.exc_type.__name__)
         if exc_type != self.exc_type:
             return False
-        if not re.match(self.value_re, str(exc_value)):
-            raise AssertionError('"%s" does not match "%s".' %
-                                 (str(exc_value), self.value_re))
+        if self.value_re:
+            matcher = MatchesException(self.exc_type, self.value_re)
+            mismatch = matcher.match((exc_type, exc_value, traceback))
+            if mismatch:
+                raise AssertionError(mismatch.describe())
         return True
 
 

testtools/tests/test_matchers.py

@@ -258,10 +258,8 @@ class TestMatchesExceptionTypeReInterface(TestCase, TestMatchersInterface):
          MatchesException(Exception, 'fo.'))
         ]
     describe_examples = [
-        # XXX: This is kind of a crappy message. Need to change
-        # AfterPreproccessing.
-        ("'bar' does not match 'fo.': after %r on %r"
-         % (str, error_bar[1]), error_bar, MatchesException(ValueError, "fo.")),
+        ("'bar' does not match 'fo.'",
+         error_bar, MatchesException(ValueError, "fo.")),
         ]
 
 
@@ -736,9 +734,10 @@ class TestAfterPreprocessing(TestCase, TestMatchersInterface):
         ]
 
     describe_examples = [
-        ("1 != 0: after <function parity> on 2",
-         2,
+        ("1 != 0: after <function parity> on 2", 2,
          AfterPreprocessing(parity, Equals(1))),
+        ("1 != 0", 2,
+         AfterPreprocessing(parity, Equals(1), annotate=False)),
         ]
 
 

testtools/tests/test_with_with.py

@@ -8,6 +8,11 @@ from testtools import (
     ExpectedException,
     TestCase,
     )
+from testtools.matchers import (
+    AfterPreprocessing,
+    Equals,
+    )
+
 
 class TestExpectedException(TestCase):
     """Test the ExpectedException context manager."""
@@ -16,13 +21,30 @@ class TestExpectedException(TestCase):
         with ExpectedException(ValueError, 'tes.'):
             raise ValueError('test')
 
+    def test_pass_on_raise_matcher(self):
+        with ExpectedException(
+            ValueError, AfterPreprocessing(str, Equals('test'))):
+            raise ValueError('test')
+
     def test_raise_on_text_mismatch(self):
         try:
             with ExpectedException(ValueError, 'tes.'):
                 raise ValueError('mismatch')
         except AssertionError:
             e = sys.exc_info()[1]
-            self.assertEqual('"mismatch" does not match "tes.".', str(e))
+            self.assertEqual("'mismatch' does not match 'tes.'", str(e))
+        else:
+            self.fail('AssertionError not raised.')
+
+    def test_raise_on_general_mismatch(self):
+        matcher = AfterPreprocessing(str, Equals('test'))
+        value_error = ValueError('mismatch')
+        try:
+            with ExpectedException(ValueError, matcher):
+                raise value_error
+        except AssertionError:
+            e = sys.exc_info()[1]
+            self.assertEqual(matcher.match(value_error).describe(), str(e))
         else:
             self.fail('AssertionError not raised.')
 
@@ -45,3 +67,7 @@ class TestExpectedException(TestCase):
             self.assertEqual('TypeError not raised.', str(e))
         else:
             self.fail('AssertionError not raised.')
+
+    def test_pass_on_raise_any_message(self):
+        with ExpectedException(ValueError):
+            raise ValueError('whatever')