Create a mock with behavior based on specific input

I'm trying to write a mock test for a class, and want to mock the output based on specific input.

Here is my Test Class

classdef MyClass
    methods
        function [out1, out2] = myMethod(obj, in1, in2, in3)
            out1 = in1 + in2 + in3;
            out2 = in1 * in2 * in3;
        end
    end
end

Based on MATLAB help section withExactInput and withAnyInputs doesnt take any inputs, Attempting to do so raises the error

So how to mock a test where same methods needs to be called with 2 differnet inputs and check the outputs.

classdef MyTest < matlab.mock.TestCase
    methods (Test)
        function testMultiInputOutputMethod(testCase)
            % Create a mock object and its behavior controller
            [mock, behavior] = testCase.createMock(?MyClass);
            
            % Define the behavior of the mock object's method for specific inputs
            testCase.assignOutputsWhen(withExactInput(behavior.myMethod(1, 2, 3)), {6, 6}); % Errors out
            testCase.assignOutputsWhen(withAnyInputs(behavior.myMethod(2, 3, 4)), {9, 24}); % Errors out
            
            % Use the mock object as if it were the real object
            [out1a, out2a] = mock.myMethod(1, 2, 3);
            [out1b, out2b] = mock.myMethod(2, 3, 4);
            
            % Verify the results
            testCase.verifyEqual(out1a, 6);
            testCase.verifyEqual(out2a, 6);
            testCase.verifyEqual(out1b, 9);
            testCase.verifyEqual(out2b, 24);
            
            % Verify that the mock object's methods were called with specific arguments
            testCase.verifyCalled(behavior.myMethod(1, 2, 3));
            testCase.verifyCalled(behavior.myMethod(2, 3, 4));
        end
    end
end

I know the above 'MyClass' doesnt need a mock, Any solution to the above problem would be helpful...

Answer 1

[Ayush Singh]

Hey Jeevraj!

To test the myMethod of MyClass with different inputs using mocks in MATLAB, you can use the MATLAB Unit Test Framework to create a mock object and define its behavior for different inputs.

However, since you want to test the actual method implementation with different inputs, you don't need to mock the method itself as you stated in your question. Instead, you can directly call the method with different inputs in your test case and verify the outputs.

classdef MyClassTest < matlab.unittest.TestCase
    methods (Test)
        function testMultiInputOutputMethod(testCase)
            % Create an instance of MyClass
            obj = MyClass();
            
            % Test 1: Call myMethod with first inputs
            [out1, out2] = obj.myMethod(1, 2, 3);
            testCase.verifyEqual(out1, 6);
            testCase.verifyEqual(out2, 6);
            
            % Test 2: Call myMethod with second inputs
            [out1, out2] = obj.myMethod(4, 5, 6);
            testCase.verifyEqual(out1, 15);
            testCase.verifyEqual(out2, 120);
        end
    end
end

I hope it answers your question!

[Jeevraj Hejmady]

Hey Ayush Singh !!

Thanks for the suggestion, I was specifically looking specifically into the mock for a different problem, the above code was an example [a pseudo-code] to address the issue.

Digging bit deeper into MATLAB help, The solution simply was to proceed without using either `withExactInput` or `withAnyInputs`, wihtout that the tests are working as expected

classdef MyTest < matlab.mock.TestCase
    methods (Test)
        function testMultiInputOutputMethod(testCase)
            % Create a mock object and its behavior controller
            [mock, behavior] = testCase.createMock(?MyClass);
            
            % Define the behavior of the mock object's method for specific inputs
            testCase.assignOutputsWhen(behavior.myMethod(3, 4, 5), 99, 98); 
            testCase.assignOutputsWhen(behavior.myMethod(2, 3, 4), 97, 96); 
            
            % Use the mock object as if it were the real object
            [out1a, out2a] = mock.myMethod(1, 2, 3);
            [out1b, out2b] = mock.myMethod(2, 3, 4);
            [out1c, out2c] = mock.myMethod(3, 4, 5);
            
            % Verify the results
            testCase.verifyEqual(out1a, 6);
            testCase.verifyEqual(out2a, 6);
            testCase.verifyEqual(out1b, 97);
            testCase.verifyEqual(out2b, 96);
            testCase.verifyEqual(out1c, 99);
            testCase.verifyEqual(out2c, 98);
            
            % Verify that the mock object's methods were called with specific arguments
            testCase.verifyCalled(behavior.myMethod(3, 4, 5));
            testCase.verifyCalled(behavior.myMethod(2, 3, 4));
        end
    end
end