Add a Not comparator to compose with other comparators.

Patch by: Benoit Sigoure <benoits@google.com>

2 files changed, 66 insertions, 0 deletions

diff --git a/mox.py b/mox.py
index 70fba4f..0dd4cc2 100755
--- a/mox.py
+++ b/mox.py
@@ -965,6 +965,40 @@ class In(Comparator):
     return '<sequence or map containing \'%s\'>' % self._key
 
 
+class Not(Comparator):
+  """Checks whether a predicates is False.
+
+  Example:
+    mock_dao.UpdateUsers(Not(ContainsKeyValue('stevepm', stevepm_user_info)))
+  """
+
+  def __init__(self, predicate):
+    """Initialize.
+
+    Args:
+      # predicate: a Comparator instance.
+    """
+
+    assert isinstance(predicate, Comparator), ("predicate %r must be a"
+                                               " Comparator." % predicate)
+    self._predicate = predicate
+
+  def equals(self, rhs):
+    """Check to see whether the predicate is False.
+
+    Args:
+      rhs: A value that will be given in argument of the predicate.
+
+    Returns:
+      bool
+    """
+
+    return not self._predicate.equals(rhs)
+
+  def __repr__(self):
+    return '<not \'%s\'>' % self._predicate
+
+
 class ContainsKeyValue(Comparator):
   """Checks whether a key/value pair is in a dict parameter.
 
diff --git a/mox_test.py b/mox_test.py
index be35bae..5f00f0c 100755
--- a/mox_test.py
+++ b/mox_test.py
@@ -159,6 +159,38 @@ class InTest(unittest.TestCase):
     self.assert_(mox.In("test") == {"test" : "module"})
 
 
+class NotTest(unittest.TestCase):
+  """Test Not correctly identifies False predicates."""
+
+  def testItemInList(self):
+    """Should return True if the item is NOT in the list."""
+    self.assert_(mox.Not(mox.In(42)) == [1, 2, 3])
+
+  def testKeyInDict(self):
+    """Should return True if the item is NOT a key in a dict."""
+    self.assert_(mox.Not(mox.In("foo")) == {"key" : 42})
+
+  def testInvalidKeyWithNot(self):
+    """Should return False if they key is NOT in the dict."""
+    self.assert_(mox.Not(mox.ContainsKeyValue("qux", 1)) == {"key": 2})
+
+
+class NotTest(unittest.TestCase):
+  """Test Not correctly identifies False predicates."""
+
+  def testItemInList(self):
+    """Should return True if the item is NOT in the list."""
+    self.assert_(mox.Not(mox.In(42)) == [1, 2, 3])
+
+  def testKeyInDict(self):
+    """Should return True if the item is NOT a key in a dict."""
+    self.assert_(mox.Not(mox.In("foo")) == {"key" : 42})
+
+  def testInvalidKeyWithNot(self):
+    """Should return False if they key is NOT in the dict."""
+    self.assert_(mox.Not(mox.ContainsKeyValue("qux", 1)) == {"key": 2})
+
+
 class StrContainsTest(unittest.TestCase):
   """Test StrContains correctly checks for substring occurrence of a parameter.
   """