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Anna
Anna

Reputation: 571

Swift Unit Test how to set with a private setter

Here is a little background:

I am trying to test some functions. I CANNOT change anything in the function or any class variables.

So I am calling this function in my unit test, the problem is that, there is a boolean flag, this method simply will just not execute if this flag is not set to true. But this flag has a private setter, so I can directly set it.

I asked around someone told me to use a extension IN the test file to set the variable, but I've tried I don't think I can set it if the extension is not in the same file as the function. Am I doing something wrong? Or is there any other way to test it?

Upvotes: 0

Views: 1473

Answers (1)

Rob Napier
Rob Napier

Reputation: 299265

What they were referring to is to place an extension in the file with the class-under-test. So if you have something like:

class ToBeTested {
    private(set) var bool: Bool
}

You can add an internal setter:

extension ToBeTested {
    func setBoolTrue() { bool = true }
}

But this has to be in the same file with ToBeTested. If you cannot modify that file, this is not a solvable problem. If it needs to be tested this way, then the class will need to be designed to permit that.

When a property is marked private(set), the compiler can assume that the value cannot be changed in any way outside this file. That allows it to apply optimizations that may not be valid if the property were changeable outside this file. The "setter method" may not even exist if the compiler determines that it doesn't need it. For example, it may completely inline that operation, or eliminate it entirely if it can prove the value is never changed.

Upvotes: 1

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