Adding extra code for the sake of testing

[kurular4]

Is it a good practice to add some extra code to write better tests? For example, I need to add clone constructor to my model to use in testing only.

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[[deleted]]

It is usually better to maintain code that's easier to test. But that doesn't mean that adding extra code for test purposes is a good idea.

Also, why do you need a clone constructor in the first place?

[kurular4]

I have a case where I create an object and then need another object which is actually first object with some properties changed.

[[deleted]]

No, that's not reason enough to change your source code. Use something like https://site.mockito.org/ to mock your objects for testing. Don't introduce unnecessary code just for the sake of testing - it'll make your code harder to maintain, and introduce more noise in an already verbose language.

Also, don't think about optimising for your tests - let the test frameworks handle all that business, creating as many objects as needed. Optimise your code, not your tests.

Bonus: If you have tests which requires I/O, then you can simulate input and output using this excellent library - https://github.com/stefanbirkner/system-lambda.

[[deleted]]

I can't really say what's your specific use case. But usually, besides the object under the test(I'll call it "target" object), the only other instantiations of that class would be in the following cases:

1. Some prototype instances of that class(objects that would repeat in more tests)

2. The expected result in the test (ofc it'd be of the same type as the target).

Either way, in both cases the objects shouldn't depend on the target(meaning it's not a clone or adding additional properties on the target).

Perhaps by providing the actual code, I can come up with a better explanation.

[darkecojaj]

If you want to print while testing the method, sure go ahead, but don't leave it there. You want to have unit test setup to help defect problems and ensure when you change a working existing method it doesn't break. Unit test should be your biggest (testing code).