在go中测试不可返回的方法

Question

I have a simple method, which just checks if a parameter is empty and then calls one of 2 methods based on a struct field.
How would I test it?

func (cT *customType) someMethod(message string) {
    if message == ""{
        return
    }

    if cT.value == nil {
        cT.doFunctionOne()
    } else {
        cT.doFunctionTwo()
    }
}

In Javascript, I would create a spy on doFunctionOne() and mock up the object.
Mocking up works well in Go as well, but how would I do the 'spying' part?
Or is there another idiomatic way to test this kind of method?

Answer 1

First: You wouldn't name a method "doFunctionOne" but "methodOne" :-)

If neither doFunctionOne nor doFunctionTwo has any observable effect, then there is absolutely no point in testing it. So we may assume that they do have observable side effect, either on the environment or on the customType they have been invoked on.

Now just test these side effects. This is trivial if both methods do return. If they spin up an endless loop it becomes harder, but still doable.

IMHO there is no need to "test" this method in the sense of "test whether it calls One or Two depending on value": For me this is to lowlevel, too much increasing coverage count for nothing. If you call some method it has to do something (observable effect) and you should check this effect, not the inner workings.