How to test custom class with unit test class

Question

Christian 2024-9-9，9:45

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https://ww2.mathworks.cn/matlabcentral/answers/2151269-how-to-test-custom-class-with-unit-test-class

评论： Christian 2024-9-9，13:12

Since, I'am very new to the topic of MatLab unit tests, I struggle with testing a custom MatLab class using a unit test class in a separate file.

Like I know from other programming languages, I would like to write a unit test (in a separate class) for a custom MatLab class. However, I do not see how to create an instance of / how to use my custom class within the test class.

Therefore, I would have the following questions, where I hope you can help me:

How do I properly create an instance of my custom class within the test class?
When I place my test class file in a sub-directory "tests/", how do I include the file of the my custom class?
Can you recommend a proper folder structure? Concrete, is it appropriate to place test classes in a sub-folder tests/

Thank you very much!

PS: Up to now - as minimal example - I have a file with a custom class MyMath.m:

classdef MyMath
    methods
        function obj = MyMath()
        end
        
        function outputArg = add(~, a1, a2)
            outputArg = a1+a2;
        end
    end
end

and a file with the test class MyMath_Test.m

classdef MyMath_Test < matlab.unittest.TestCase
    methods(TestClassSetup)
        % Shared setup for the entire test class
        my_math = MyMath();
    end
    
    methods(TestMethodSetup)
        % Setup for each test
    end
    
    methods(Test)
        % Test methods
        
        function unimplementedTest(testCase)
            res = my_math.add(4,5);
            testCase.verifyEqual(res, 9)
        end
    end 
end

Running Tests via Matlab GUI Buttons, results in the error:

>> runtests("MyMath_Test")

Running MyMath_Test

================================================================================

Error occurred while setting up or tearing down MyMath_Test.

As a result, all MyMath_Test tests failed and did not run to completion.

---------

Error ID:

---------

'MATLAB:TooManyInputs'

--------------

Error Details:

--------------

Error using MyMath_Test/MyMath

Too many input arguments.

================================================================================

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Answer 1

Jatin 2024-9-9，11:08

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在 MATLAB Online 中打开

Hi @Christian,

To correctly create an instance of your custom class within the test class, define a property in the test class that is accessible to all test methods. This can be achieved using the "properties" block.

If your test class is located in a subdirectory, ensure that directory is included in MATLAB's path by using the "Add to Path" option.

Organizing your test cases in a subdirectory named "tests/" is a good practice, as it helps keep your code well-organized.

Here is a correct example of a unit test class for the custom class you mentioned.

classdef MyMath
    methods
        function obj = MyMath()
        end
        
        function outputArg = add(~, a1, a2)
            outputArg = a1 + a2;
        end
    end
end

Test class:

classdef MyMath_Test < matlab.unittest.TestCase
    properties
        myMath % Property to hold an instance of MyMath
    end
    methods(TestMethodSetup)
        function createMyMathInstance(testCase)
            % Setup for each test - create an instance of MyMath
            testCase.myMath = MyMath();
        end
    end
    
    methods(Test)
        function testAddMethod(testCase)
            % Test the add method
            res = testCase.myMath.add(4, 5);
            testCase.verifyEqual(res, 9);
        end
    end
end

Kindly go through the below documentation for more on "Ways to right unit tests":

https://www.mathworks.com/help/matlab/matlab_prog/ways-to-write-unit-tests.html

Hope this helps!

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Answer 2

Deepak Gupta 2024-9-9，11:27

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编辑：Deepak Gupta 2024-9-9，11:28

在 MATLAB Online 中打开

Hi,

Methods keyword is used to define a wrapper for all the method which need to run during class setup or method setup or test themselve, just like you have done for methods(Test) . Here is updated code, with few changes.

classdef MyMath_Test < matlab.unittest.TestCase
    properties
        my_math % You have defined your class object in a TestClassSetup. It needs to be declared first
        %  as a property I would rather suggest you to create class object
        %  inside test method or TestMethodSetup so object gets created for
        %  each run individually.
    end
    methods(TestClassSetup)
        % To answer your question, regarding where to place tests. You can
        % place them anywhere. I would suggest you create a separate
        % directly for tests from source. You can use path fixture to add
        % source path for your test to use at runtime. Any function defined
        % as TestClassSetup will only run once at the start of this test.
        function pathFixture(testCase)
            import matlab.unittest.fixtures.PathFixture
            testCase.applyFixture(PathFixture("SourcePath\Custom_Class"))
        end
    end
    
    methods(TestMethodSetup)
        % Any function defined as TestMethodSetup will run for each test
        % point and will create and destruct objects automatically after
        % test point is complete
        function CreateClassObject(testCase)
            testCase.my_math = MyMath();
        end
    end
    
    methods(Test)
        % Test methods
        function unimplementedTest(testCase)
            res = testCase.my_math.add(4,5);
            testCase.verifyEqual(res, 9)
        end
    end 
end

If you create object inside test method itself it will be like this:

classdef MyMath_Test2 < matlab.unittest.TestCase
    methods(TestClassSetup)
        function pathFixture(testCase)
            import matlab.unittest.fixtures.PathFixture
            testCase.applyFixture(PathFixture("SourcePath\Custom_Class"))
        end
    end
    methods(Test)
        % Test methods
        function unimplementedTest(testCase)
            my_math = MyMath();
            res = my_math.add(4,5);
            testCase.verifyEqual(res, 9)
        end
    end 
end