answerservice_test.go

func TestGetAnswer(t *testing.T) {
	httpmock.Activate()
	defer httpmock.DeactivateAndReset()

	httpmock.RegisterResponder("GET", "https://localhost:8080/answer",
		httpmock.NewStringResponder(200, `{"answer": 42}`))
}

func TestPostAnswer(t *testing.T) {
	httpmock.Activate()
	defer httpmock.DeactivateAndReset()

	httpmock.RegisterResponder("POST", affiliationUrl, 
		httpmock.NewStringResponder(201, `{"answer": 42}`))
}

func TestMockingUniverse(t *testing.T) {
	ctrl := gomock.NewController(t)
	providerUniverse := mock.NewMockUniverse(ctrl)
	defer ctrl.Finish()

	providerUniverse.GiveMeTheAnswer().Return(42, nil)
	universe.SetProvider(providerUniverse)
}

eita.go

package universe

import "github.com/crissilvaeng/goseed/api/universe"

var provider Universe

func init() {
	provider = new(universe)
}

func Provider() Universe {
	return provider
}

func SetProvider(universe Universe) {
	provider = universe
}

type Universe interface {
	GiveMeTheAnswer() (int, error)
}

type universe struct{}

func (u *universe) GiveMeTheAnswer() (int, error) {
	return u.Answer()
}

math_test.go

package math

import "testing"

type testpair struct {
  values []float64
  average float64
}

var tests = []testpair{
  { []float64{1,2}, 1.5 },
  { []float64{1,1,1,1,1,1}, 1 },
  { []float64{-1,1}, 0 },
}

func TestAverage(t *testing.T) {
  for _, pair := range tests {
    v := Average(pair.values)
    if v != pair.average {
      t.Error(
        "For", pair.values,
        "expected", pair.average,
        "got", v,
      )
    }
  }
}

result.txt

λ go test -v
=== RUN   TestAnswers
=== RUN   TestAnswers/Answers=42
=== RUN   TestAnswers/Answers=Batata
--- PASS: TestAnswers (0.00s)
    --- PASS: TestAnswers/Answers=42 (0.00s)
    --- PASS: TestAnswers/Answers=Batata (0.00s)
PASS
ok      github.com/crissilvaeng/goseed/api/universe     0.026s

universe.go

package universe

// Answer to life, the universe and everything.
func Answer() int {
	return 42
}

// OtherAnswer to life, the universe and everything.
func OtherAnswer() string {
	return "batata"
}

universe_test.go

package universe

import "testing"

func TestAnswers(t *testing.T) {
	t.Run("Answers=42", func(t *testing.T) {
		expected := 42
		actual := Answer()

		if expected != actual {
			t.Errorf("The anwser should be %d and got %d.", expected, actual)
		}
	})
	t.Run("Answers=Batata", func(t *testing.T) {
		expected := "batata"
		actual := OtherAnswer()

		if expected != actual {
			t.Errorf("The anwser should be %s and got %s.", expected, actual)
		}
	})
}