diff -r bbfbde6ee9d0 -r b609f807021b Doc/library/unittest.mock.rst
--- a/Doc/library/unittest.mock.rst	Thu Feb 18 17:34:32 2016 +0200
+++ b/Doc/library/unittest.mock.rst	Fri Feb 19 09:29:51 2016 +1100
@@ -259,6 +259,34 @@
     used to set attributes on the mock after it is created. See the
     :meth:`configure_mock` method for details.
 
+    .. method:: assert_called(*args, **kwargs)
+
+        Assert that the mock was called.
+
+            >>> mock = Mock()
+            >>> mock.method()
+            <Mock name='mock.method()' id='...'>
+            >>> mock.method.assert_called()
+
+        .. versionadded:: 3.6
+
+    .. method:: assert_called_once(*args, **kwargs)
+
+        Assert that the mock was called exactly once.
+
+            >>> mock = Mock()
+            >>> mock.method()
+            <Mock name='mock.method()' id='...'>
+            >>> mock.method.assert_called_once()
+            >>> mock.method()
+            <Mock name='mock.method()' id='...'>
+            >>> mock.method.assert_called_once()
+            Traceback (most recent call last):
+            ...
+            AssertionError: Expected 'method' to have been called once. Called 2 times.
+
+        .. versionadded:: 3.6
+
 
     .. method:: assert_called_with(*args, **kwargs)
 
diff -r bbfbde6ee9d0 -r b609f807021b Doc/whatsnew/3.6.rst
--- a/Doc/whatsnew/3.6.rst	Thu Feb 18 17:34:32 2016 +0200
+++ b/Doc/whatsnew/3.6.rst	Fri Feb 19 09:29:51 2016 +1100
@@ -161,6 +161,18 @@
 Stéphane Wirtel in :issue:`25485`).
 
 
+unittest.mock
+-------------
+
+The :class:`~unittest.mock.Mock` class has the following improvements:
+
+* Two new methods, :meth:`Mock.assert_called()
+  <unittest.mock.Mock.assert_called>` and :meth:`Mock.assert_called_once()
+  <unittest.mock.Mock.assert_called_once>` to check if the mock object
+  was called.
+  (Contributed by Amit Saha in :issue:`26323`.)
+
+
 urllib.robotparser
 ------------------
 
diff -r bbfbde6ee9d0 -r b609f807021b Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Thu Feb 18 17:34:32 2016 +0200
+++ b/Lib/unittest/mock.py	Fri Feb 19 09:29:51 2016 +1100
@@ -772,6 +772,24 @@
                    (self._mock_name or 'mock', self.call_count))
             raise AssertionError(msg)
 
+    def assert_called(_mock_self):
+        """assert that the mock was called at least once
+        """
+        self = _mock_self
+        if self.call_count == 0:
+            msg = ("Expected '%s' to have been called." %
+                   self._mock_name or 'mock')
+            raise AssertionError(msg)
+
+    def assert_called_once(_mock_self):
+        """assert that the mock was called only once.
+        """
+        self = _mock_self
+        if not self.call_count == 1:
+            msg = ("Expected '%s' to have been called once. Called %s times." %
+                   (self._mock_name or 'mock', self.call_count))
+            raise AssertionError(msg)
+
     def assert_called_with(_mock_self, *args, **kwargs):
         """assert that the mock was called with the specified arguments.
 
diff -r bbfbde6ee9d0 -r b609f807021b Lib/unittest/test/testmock/testmock.py
--- a/Lib/unittest/test/testmock/testmock.py	Thu Feb 18 17:34:32 2016 +0200
+++ b/Lib/unittest/test/testmock/testmock.py	Fri Feb 19 09:29:51 2016 +1100
@@ -1222,6 +1222,28 @@
         with self.assertRaises(AssertionError):
             m.hello.assert_not_called()
 
+    def test_assert_called(self):
+        m = Mock()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called()
+        m.hello()
+        m.hello.assert_called()
+
+        m.hello()
+        m.hello.assert_called()
+
+    def test_assert_called_once(self):
+        m = Mock()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called_once()
+        m.hello()
+        m.hello()
+        with self.assertRaises(AssertionError):
+            m.hello.assert_called_once()
+        m.reset_mock()
+        m.hello()
+        m.hello.assert_called_once()
+
     #Issue21256 printout of keyword args should be in deterministic order
     def test_sorted_call_signature(self):
         m = Mock()