Mocking in Go Part 2

go get github.com/golang/mock/mockgen@latest

module jcheng.org

go 1.13

require (
	github.com/golang/mock v1.4.0
)

//go:generate mockgen -source $GOFILE -destination mock_$GOFILE -package $GOPACKAGE
package pastself

import (
	"time"
)
...

type fnmatcher struct {
	d    func(x interface{}) bool
	desc string
}

func (self *fnmatcher) Matches(x interface{}) bool {
	return self.d(x)
}

func (self *fnmatcher) String() string {
	return self.desc
}

func On(desc string, d func(x interface{}) bool) mock.Matcher {
	return &fnmatcher{d: d, desc: desc}
}

// TestSendOverdueMessages_ok is an example of using matching using a callback function
func TestSendOverdueMessages_ok(t *testing.T) {
	ctrl := mock.NewController(t)
	defer ctrl.Finish()

	mockUserRepo := NewMockUserRepository(ctrl)
	mockMessageRepo := NewMockMessageRepository(ctrl)
	mockMessageSender := NewMockMessageSender(ctrl)
	log, _ := NewBufferLog()
	r := NewPastSelfService(
		mockMessageRepo,
		mockMessageSender,
		mockUserRepo,
		log,
	)

	senderUserDDB_1 := &UserDDB{UserID: "sender1"}
	senderUserDDB_2 := &UserDDB{UserID: "sender2"}
	recipientUserDDB_2 := &UserDDB{
		UserID: "recipient2",
		Profile: UserProfileDDB{
			PreferredEmail: "recipient2@example.com",
		},
	}
	resultSet := &ResultSet{
		Items: []Message{
			{
				ID:         1,
				SenderID:   "sender1",
				Body:       "body1",
				Recipients: []string{"email://recipient1@example.com", "recipient2"},
				Headers: []Header{
					{Name: "x-header-key-1", Value: "value-1"},
					{Name: "x-header-key-2", Value: "value-2"},
				},
			},
			{
				ID:       2,
				SenderID: "sender2",
				Body:     "body2",
			},
		},
	}
	mockUserRepo.EXPECT().GetUser("sender1").Return(senderUserDDB_1, nil)
	mockUserRepo.EXPECT().GetUser("sender2").Return(senderUserDDB_2, nil)
	mockUserRepo.EXPECT().GetUser("recipient2").Return(recipientUserDDB_2, nil)
	mockMessageRepo.EXPECT().FindOverdue(mock.Any(), 0, "").Return(resultSet, nil)

	matchFrom := On("user.UserID==sender1", func(x interface{}) bool {
		if y, ok := x.(*UserDDB); ok {
			return y.UserID == "sender1"
		}
		return false
	})
	matchTo := On("[]Recipient{recipient1@example.com,recipient2@example.com}", func(x interface{}) bool {
		if y, ok := x.([]Recipient); ok {
			return len(y) == 2 &&
				y[0].Email == "recipient1@example.com" &&
				y[1].Email == "recipient2@example.com"
		}
		return false
	})
	matchOutMessage := On("OutboundMessage.Body==Body1", func(x interface{}) bool {
		if y, ok := x.(OutboundMessage); ok {
			return y.Body == "body1"
		}
		return false
	})
	mockMessageSender.EXPECT().Send(matchFrom, matchTo, matchOutMessage).Return(nil).MaxTimes(1)

	r.SendOverdueMessages()
}