How to specify returning a value given a specific argument?

[chintanparikh]

Hi -

I have an interface with a method that is called multiple times where I can't guarantee the order it's called in. However, the arguments on each call are different. Is there any way for me to specify a return value for specific arguments? E.g. something like:

interface Adder {
	Add(a int, b int) c int
}

fakeAdder.ReturnsWithArguments(1, 1, 3)

This would return 3 whenever someone calls adder.Add(1, 1)

[hoegaarden]

This is nothing that counterfeiter comes with OOTB, however you can implement it relatively easy yourself by providing a stub:

func TestSomething(t *testing.T) {
	fakeAdder := foooofakes.FakeAdder{}

	fakeAdder.AddCalls(func(a, b int) int {
		specialCases := map[int]map[int]int{
			1: {0: 20, 1: 30, 2: 40},
			2: {1: 45, 2: 55},
		}

		if x, ok := specialCases[a]; ok {
			if y, ok := x[b]; ok {
				return y
			}
		}

		return -1
	})

	for a := 0; a < 3; a++ {
		for b := 0; b < 4; b++ {
			t.Logf("Add(%d, %d) = %d", a, b, fakeAdder.Add(a, b))
		}
	}
}