unittest.mock: asserting partial match for method argument

unittest.mock: asserting partial match for method argument

To assert a partial match for method arguments using unittest.mock in Python, you can use the unittest.mock.call_args or unittest.mock.call_args_list attributes to inspect the arguments passed to a mocked method and then perform partial matching on those arguments. Here's how you can do it:

Suppose you have a class with a method you want to mock and you want to assert that the method was called with specific argument values that match partially:

import unittest from unittest.mock import Mock, call class MyClass: def my_method(self, arg1, arg2): pass # Create an instance of MyClass my_instance = MyClass() # Mock the method my_instance.my_method = Mock() # Call the method with arguments my_instance.my_method('apple', 'banana') # Assert a partial match for the method call expected_args = ('app', 'ban') # Partial match my_instance.my_method.assert_called_once_with(*expected_args)

In this example:

  1. We have a class MyClass with a method my_method.

  2. We create an instance of MyClass.

  3. We mock the my_method using unittest.mock.Mock().

  4. We call the method with arguments 'apple' and 'banana'.

  5. We define expected_args as a tuple of expected argument values for the partial match.

  6. We use assert_called_once_with(*expected_args) to assert that the my_method was called once with arguments that partially match the expected_args.

This way, you can perform partial matching on the arguments passed to a mocked method using unittest.mock. Adjust the expected_args as needed for your specific partial matching criteria.

Examples

  1. Query: How to mock a single function with multiple calls in Python using unittest.mock?

    • Description: To mock a single function and control its behavior, you can use the unittest.mock.patch() method. This snippet demonstrates how to mock a function that's called multiple times within a unit test.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" def caller_function(self): return self.my_function() * 2 # Call my_function twice class TestMockFunction(unittest.TestCase): @patch.object(MyClass, 'my_function', return_value="mocked value") def test_mock_my_function(self, mock_my_function): obj = MyClass() # Test the function that calls my_function twice result = obj.caller_function() self.assertEqual(result, "mocked value" * 2) # Ensure my_function was called twice self.assertEqual(mock_my_function.call_count, 2) if __name__ == '__main__': unittest.main()

  2. Query: How to mock only one specific method in Python unit tests?

    • Description: To mock only one specific method while leaving others unmocked, you can use unittest.mock.patch.object(). This example shows how to mock a specific method without affecting others.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" def another_function(self): return "another original value" class TestMockSpecificMethod(unittest.TestCase): @patch.object(MyClass, 'my_function', return_value="mocked value") def test_mock_specific_method(self, mock_my_function): obj = MyClass() # Call my_function and another_function result1 = obj.my_function() result2 = obj.another_function() self.assertEqual(result1, "mocked value") # Mocked self.assertEqual(result2, "another original value") # Not mocked if __name__ == '__main__': unittest.main()

  3. Query: How to use side effects to change mock return values with multiple calls?

    • Description: To change the return value of a mock with each call, you can use side_effect. This snippet demonstrates how to set different return values for each call.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" class TestMockSideEffect(unittest.TestCase): @patch.object(MyClass, 'my_function', side_effect=["mocked value 1", "mocked value 2"]) def test_mock_with_side_effect(self, mock_my_function): obj = MyClass() # Call my_function twice with different return values result1 = obj.my_function() # First call result2 = obj.my_function() # Second call self.assertEqual(result1, "mocked value 1") self.assertEqual(result2, "mocked value 2") if __name__ == '__main__': unittest.main()

  4. Query: How to assert that a mocked function is called a specific number of times in Python unit tests?

    • Description: To assert the number of times a mocked function is called, you can use the call_count attribute. This snippet demonstrates how to verify the number of calls.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" class TestMockCallCount(unittest.TestCase): @patch.object(MyClass, 'my_function', return_value="mocked value") def test_mock_call_count(self, mock_my_function): obj = MyClass() # Call my_function three times obj.my_function() obj.my_function() obj.my_function() self.assertEqual(mock_my_function.call_count, 3) # Assert the call count if __name__ == '__main__': unittest.main()

  5. Query: How to mock a function with multiple calls and check the arguments in Python unit tests?

    • Description: To check the arguments passed to a mocked function, you can use the call_args_list attribute. This example demonstrates how to verify the arguments with multiple calls.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self, arg): return f"original value with {arg}" class TestMockCallArguments(unittest.TestCase): @patch.object(MyClass, 'my_function', return_value="mocked value") def test_mock_call_arguments(self, mock_my_function): obj = MyClass() # Call my_function with different arguments obj.my_function("arg1") obj.my_function("arg2") # Check the arguments passed to the mocked function self.assertEqual(mock_my_function.call_args_list[0], (('arg1',), {})) self.assertEqual(mock_my_function.call_args_list[1], (('arg2',), {})) if __name__ == '__main__': unittest.main()

  6. Query: How to mock a function and assert that it returns a specific value with each call?

    • Description: To ensure a mocked function returns a specific value with each call, you can use side_effect or return_value. This example demonstrates how to assert the expected return value for each call.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" class TestMockReturnValues(unittest.TestCase): @patch.object(MyClass, 'my_function', return_value="mocked value") def test_mock_return_values(self, mock_my_function): obj = MyClass() # Call my_function and check the return value result = obj.my_function() self.assertEqual(result, "mocked value") # Assert the expected return value if __name__ == '__main__': unittest.main()

  7. Query: How to mock a class method and ensure it is called with specific arguments?

    • Description: To mock a class method and ensure it is called with specific arguments, you can use the assert_called_with() method. This snippet demonstrates how to assert specific arguments.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_method(self, arg): return f"original value with {arg}" class TestMockMethodArguments(unittest.TestCase): @patch.object(MyClass, 'my_method', return_value="mocked value") def test_mock_method_arguments(self, mock_my_method): obj = MyClass() # Call my_method with an argument obj.my_method("expected_arg") # Assert the method is called with the specific argument mock_my_method.assert_called_with("expected_arg") if __name__ == '__main__': unittest.main()

  8. Query: How to mock a function and set its return value for each call?

    • Description: To set different return values for each call to a mocked function, you can use side_effect. This example demonstrates how to mock a function and set its return value for each call.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" class TestMockFunctionReturn(unittest.TestCase): @patch.object(MyClass, 'my_function', side_effect=["value1", "value2", "value3"]) def test_mock_return_value_for_each_call(self, mock_my_function): obj = MyClass() # Call my_function multiple times and check the return values result1 = obj.my_function() result2 = obj.my_function() result3 = obj.my_function() self.assertEqual(result1, "value1") self.assertEqual(result2, "value2") self.assertEqual(result3, "value3") if __name__ == '__main__': unittest.main()

  9. Query: How to mock a function and raise an exception on specific calls?

    • Description: To mock a function and raise an exception for specific calls, you can use side_effect to define exceptions or custom logic. This snippet demonstrates how to raise exceptions with a mocked function.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self): return "original value" class TestMockFunctionException(unittest.TestCase): @patch.object(MyClass, 'my_function', side_effect=[None, Exception("Test exception")]) def test_mock_raise_exception(self, mock_my_function): obj = MyClass() # Call my_function, first without exception obj.my_function() with self.assertRaises(Exception): obj.my_function() # Second call raises an exception if __name__ == '__main__': unittest.main()

  10. Query: How to mock a function with different behaviors based on the input arguments?

    • Description: To mock a function and define custom behavior based on its input arguments, you can use side_effect with a lambda function or custom logic. This example demonstrates how to change behavior based on input.
    • Code:
      import unittest from unittest.mock import patch class MyClass: def my_function(self, arg): return f"original {arg}" class TestMockFunctionBasedOnArgs(unittest.TestCase): @patch.object(MyClass, 'my_function', side_effect=lambda x: f"mocked {x}") def test_mock_function_based_on_args(self, mock_my_function): obj = MyClass() # Call my_function with different arguments result1 = obj.my_function("input1") result2 = obj.my_function("input2") self.assertEqual(result1, "mocked input1") self.assertEqual(result2, "mocked input2") if __name__ == '__main__': unittest.main()

More Tags

poi-hssf lightgbm xcodebuild md5sum file-storage laravel-5 amazon-elb checkboxfor crash angular-changedetection

More Python Questions

More Investment Calculators

More Pregnancy Calculators

More Chemistry Calculators

More Cat Calculators