Tests for the argument captor

callee/base.py

@@ -104,6 +104,8 @@ class BaseMatcher(object):
     This class shouldn't be used directly by the client.
     To create custom matchers, inherit from :class:`Matcher` instead.
     """
+    __slots__ = ()
+
     def match(self, value):
         raise NotImplementedError("matching not implemented")
 

callee/general.py

@@ -145,8 +145,11 @@ def __init__(self, matcher=None):
         """
         if matcher is None:
             matcher = Any()
+
         if not isinstance(matcher, BaseMatcher):
             raise TypeError("expected a matcher, got %r" % (type(matcher),))
+        if isinstance(matcher, Captor):
+            raise TypeError("cannot pass a captor to another captor")
 
         self.matcher = matcher
 

tests/test_general.py

@@ -217,6 +217,87 @@ def __call__(self, _):
         return True
 
 
+# Argument captor
+
+class Captor(MatcherTestCase):
+    ARG = object()
+    FALSE_MATCHER = __unit__.Matching(lambda _: False)
+
+    def test_ctor__no_args(self):
+        captor = __unit__.Captor()
+        self.assertIsInstance(captor.matcher, __unit__.Any)
+
+    def test_ctor__invalid_matcher(self):
+        not_matcher = object()
+        with self.assertRaisesRegexp(TypeError, r'expected'):
+            __unit__.Captor(not_matcher)
+
+    def test_ctor__matcher(self):
+        matcher = __unit__.Matching(bool)
+        captor = __unit__.Captor(matcher)
+        self.assertIs(matcher, captor.matcher)
+
+    def test_ctor__captor(self):
+        captor = __unit__.Captor()
+        with self.assertRaisesRegexp(TypeError, r'captor'):
+            __unit__.Captor(captor)
+
+    def test_has_value__initial(self):
+        captor = __unit__.Captor()
+        self.assertFalse(captor.has_value())
+
+    def test_has_value__not_captured(self):
+        # When the argument fails the matcher test, it should not be captured.
+        captor = __unit__.Captor(self.FALSE_MATCHER)
+        captor.match(self.ARG)
+        self.assertFalse(captor.has_value())
+
+    def test_has_value__captured(self):
+        captor = __unit__.Captor()
+        captor.match(self.ARG)
+        self.assertTrue(captor.has_value())
+
+    def test_arg__initial(self):
+        captor = __unit__.Captor()
+        with self.assertRaisesRegexp(ValueError, r'no value'):
+            captor.arg
+
+    def test_arg__not_captured(self):
+        # When the argument fails the matcher test, it should not be captured.
+        captor = __unit__.Captor(self.FALSE_MATCHER)
+        captor.match(self.ARG)
+        with self.assertRaisesRegexp(ValueError, r'no value'):
+            captor.arg
+
+    def test_arg__captured(self):
+        captor = __unit__.Captor()
+        captor.match(self.ARG)
+        self.assertIs(self.ARG, captor.arg)
+
+    def test_match__captured(self):
+        captor = __unit__.Captor()
+        self.assertTrue(captor.match(self.ARG))
+
+    def test_match___not_captured(self):
+        captor = __unit__.Captor(self.FALSE_MATCHER)
+        self.assertFalse(captor.match(self.ARG))
+
+    def test_match__double_capture(self):
+        captor = __unit__.Captor()
+        captor.match(self.ARG)
+        with self.assertRaisesRegexp(ValueError, r'already'):
+            captor.match(self.ARG)
+
+    def test_repr__not_captured(self):
+        captor = __unit__.Captor()
+        self.assertNotIn("(*)", repr(captor))
+
+    def test_repr__captured(self):
+        captor = __unit__.Captor()
+        captor.match(self.ARG)
+        self.assertIn("(*)", repr(captor))
+
+
 # Function-related matchers
 
 class Callable(MatcherTestCase):