def test_switches_backend(self):
"""
Tests that calling an operation will switch backend if the current
backend doesn't support it
"""
def say_hello(backend):
return "Hello world!"
self.FakeBackend.operations = {
'say_hello': say_hello,
}
def say_goodbye(backend):
return "Goodbye!"
self.AnotherFakeBackend.operations = {
'say_goodbye': say_goodbye,
}
image = Image(self.FakeBackend(), 'jpeg')
self.assertIsInstance(image.backend, self.FakeBackend)
image.say_goodbye()
self.assertIsInstance(image.backend, self.AnotherFakeBackend)
image.say_hello()
self.assertIsInstance(image.backend, self.FakeBackend)
def test_save_as_foo(self):
image = Image()
image.save_as_jpeg = mock.MagicMock()
with self.assertRaises(ValueError):
image.save("foo", "outfile")
self.assertFalse(image.save_as_jpeg.mock_calls)
def test_getattr_operation(self):
"""
Tests that __getattr__ looks up operations correctly
"""
def myop(backend):
pass
self.FakeBackend.operations = {
'test': myop,
}
image = Image(self.FakeBackend(), 'jpeg')
self.assertIsInstance(image.test, types.FunctionType)
def test_return_value_gets_passed_back(self):
"""
Tests that the return value of the underlying function gets passed back
to the caller
"""
def myop(backend):
return "Hello world!"
self.FakeBackend.operations = {
'test': myop,
}
image = Image(self.FakeBackend(), 'jpeg')
self.assertEqual(image.test(), "Hello world!")
def test_getattr_operation_unknown(self):
"""
Tests that __getattr__ raises an AttributeError when the requested
attribute is not an operation
"""
def myop(backend):
pass
self.FakeBackend.operations = {
'test': myop,
}
image = Image(self.FakeBackend(), 'jpeg')
self.assertRaises(AttributeError, getattr, image, 'test2')
def test_calls_function(self):
"""
Tests that calling the operation calls the underlying function
"""
def myop(backend):
backend.func_called = True
self.FakeBackend.operations = {
'test': myop,
}
image = Image(self.FakeBackend(), 'jpeg')
image.backend.func_called = False
image.test()
self.assertTrue(image.backend.func_called)
def test_args_get_passed_through(self):
"""
Tests that args get passed through to the underlying function
"""
def myop(backend, *args, **kwargs):
backend.passed_args = args
backend.passed_kwargs = kwargs
self.FakeBackend.operations = {
'test': myop,
}
image = Image(self.FakeBackend(), 'jpeg')
image.backend.passed_args = None
image.backend.passed_kwargs = None
image.test('Hello', 'World', name="Karl")
self.assertEqual(image.backend.passed_args, ('Hello', 'World'))
self.assertEqual(image.backend.passed_kwargs, {'name': "Karl"})
def test_save_as_jpeg(self):
image = Image()
image.save_as_jpeg = mock.MagicMock()
image.save("jpeg", "outfile")
image.save_as_jpeg.assert_called_with("outfile")