[Go] gomock を使って渡された引数に応じて関数の返り値を変更する

package main

type DummyInterface interface {
    AddNumbers(a int, b int) int
}

package main

import (
    "testing"

    "github.com/golang/mock/gomock"
)

func TestAddNumbers(t *testing.T) {
    ctrl := gomock.NewController(t)
    defer ctrl.Finish()
    mockDummy := NewMockDummyInterface(ctrl)
    mockDummy.
        EXPECT().
        AddNumbers(4, 6).
        Return(12)
    mockDummy.
        EXPECT().
        AddNumbers(3, 5).
        Return(10)

    n := mockDummy.AddNumbers(3, 5)

    if n != 10 {
        t.Fatal("n is not 10")
    }

    m := mockDummy.AddNumbers(4, 6)

    if m != 12 {
        t.Fatal("m is not 12")
    }
}