Code snippet for article: Structuring Integration Testing in Golang

config.go

package config

type Config struct {
	ConnPsql string
}

// Load loads a configuration files into Config struct
func Load(path string) (Config, error) {
	return Config{}, nil
}

full_integration_test.go

// +build it

package it

import (
	"database/sql"
	"io/ioutil"
	"net/http"

	"github.com/nydan/integration_test/config"
	"github.com/nydan/integration_test/migrator"
	"github.com/nydan/integration_test/server"
	"github.com/stretchr/testify/suite"
)

// exampleTestSuite is the basic testing suite.
// Here we can place all the dependency that we need for running the test.
// In this example we can add database client connection to test cases with DB.
type exampleTestSuite struct {
	suite.Suite
	db  *sql.DB
	cfg config.Config
	srv *http.Server
}

// SetupTest initialize the testing suite dependency before the first test case executed.
// Within this step your integration test able to connect to any integrated client required
// For multiple test cases in a test suite, you may only need to initialize it once.
func (e *exampleTestSuite) SetupTest() {
	// load configuration for your application
	cfg, err := config.Load("application_cfg.toml")
	e.NoError(err, "failed to load config")
	e.cfg = cfg

	// open connection to the database
	db, err := sql.Open("postgres", e.cfg.ConnPsql)
	e.NoError(err, "failed connect to DB")
	e.NoError(db.Ping())
	e.db = db

	// migrate the database schema
	err = migrator.Up("/migrations")
	e.NoError(err, "failed to migrate up the db schema")

	// setup an http server and router
	e.srv = server.NewHTTPServer()
	go func() {
		err := e.srv.ListenAndServe()
		e.NoError(err, "failed to start HTTP server")
	}()
}

// TearDownSuite is tearing down all the setup that has been initialize in the SetupTest.
// This tear down only happen at the end of suite life cycle.
func (e *exampleTestSuite) TearDownSuite() {
	var err error

	err = e.db.Close()
	e.NoError(err, "failed to close db connection")

	err = e.srv.Close()
	e.NoError(err, "failed to shutdown HTTP server")
}

// successLoginTest contains context for the test case. The value of each field is
// initialize on setup() and will be the reference for clean up the data on clean().
type successLoginTest struct {
	id    int64
	email string
	pass  string
}

// createVerifiedUser creates a user to be tested for login API.
func (s *successLoginTest) createVerifiedUser(e *exampleTestSuite) {
	row := e.db.QueryRow(
		`INSERT INTO admin (email, password, status) VALUES ($1, $2, $3) returning id`,
		s.email, s.pass, "verified")
	err := row.Scan(&s.id)
	e.NoError(err, "failed to insert user")
}

func (s *successLoginTest) loginAPICall(e *exampleTestSuite) *http.Response {
	c := http.Client{}
	req, err := http.NewRequest(http.MethodPost, "http://localhost:8080/login", nil)
	e.NoError(err, "failed to create a request")

	resp, err := c.Do(req)
	e.NoError(err, "failed to do request")

	return resp
}

// clean cleans predefined data or produced data from the test case.
func (s *successLoginTest) clean(e *exampleTestSuite) {
	_, err := e.db.Exec(`DELETE FROM admin WHERE id = $1`, s.id)
	e.NoError(err, "failed to delete user")
}

func (s *successLoginTest) assertLoginSuccessful(e *exampleTestSuite, resp *http.Response) {
	buf, err := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()
	e.NoError(err, "failed to read response body")

	// Do all the assertion related to the response body.
	e.NotEmpty(buf)
}

// TestSuccessLogin test case that simulate a registered user try to
// login into your app. This test case specifically test your login scenario,
// and to test that particular part means we need have a predefined data
// which is a verified account.
func (e *exampleTestSuite) TestSuccessLogin() {
	tt := new(successLoginTest)
	defer tt.clean(e)
	tt.createVerifiedUser(e)
	resp := tt.loginAPICall(e)
	tt.assertLoginSuccessful(e, resp)
}

migrator.go

package migrator

// Up migrate up the sql file from the path
func Up(path string) error {
	return nil
}

// Down migrate down the sql file from the path
func Down(path string) error {
	return nil
}

server.go

package server

import "net/http"

// NewHTTPServer create a new http Server instance
func NewHTTPServer() *http.Server {
	return &http.Server{}
}

suite_part_integration_test.go

// exampleTestSuite is the basic testing suite.
// Here we can place all the dependency that we need for running the test.
// In this example we can add database client connection to test cases with DB.
type exampleTestSuite struct {
	suite.Suite
	db  *sql.DB
	cfg config.Config
	srv *http.Server
}

// SetupTest initialize the testing suite dependency before the first test case executed.
// Within this step your integration test able to connect to any integrated client required
// For multiple test cases in a test suite, you may only need to initialize it once.
func (e *exampleTestSuite) SetupTest() {
	// load configuration for your application
	cfg, err := config.Load("application_cfg.toml")
	e.NoError(err, "failed to load config")
	e.cfg = cfg

	// open connection to the database
	db, err := sql.Open("postgres", e.cfg.ConnPsql)
	e.NoError(err, "failed connect to DB")
	e.NoError(db.Ping())
	e.db = db

	// migrate the database schema
	err = migrator.Up("/migrations")
	e.NoError(err, "failed to migrate up the db schema")

	// setup an http server and router
	e.srv = server.NewHTTPServer()
	go func() {
		err := e.srv.ListenAndServe()
		e.NoError(err, "failed to start HTTP server")
	}()
}

// TearDownSuite is tearing down all the setup that has been initialize in the SetupTest.
// This tear down only happen at the end of suite life cycle.
func (e *exampleTestSuite) TearDownSuite() {
	var err error

	err = e.db.Close()
	e.NoError(err, "failed to close db connection")

	err = e.srv.Close()
	e.NoError(err, "failed to shutdown HTTP server")
}

testcase_part_integration_test.go

// successLoginTest contains context for the test case. The value of each field is
// initialize on setup() and will be the reference for clean up the data on clean().
type successLoginTest struct {
	id    int64
	email string
	pass  string
}

// createVerifiedUser creates a user to be tested for login API.
func (s *successLoginTest) createVerifiedUser(e *exampleTestSuite) {
	row := e.db.QueryRow(
		`INSERT INTO admin (email, password, status) VALUES ($1, $2, $3) returning id`,
		s.email, s.pass, "verified")
	err := row.Scan(&s.id)
	e.NoError(err, "failed to insert user")
}

func (s *successLoginTest) loginAPICall(e *exampleTestSuite) *http.Response {
	c := http.Client{}
	req, err := http.NewRequest(http.MethodPost, "http://localhost:8080/login", nil)
	e.NoError(err, "failed to create a request")

	resp, err := c.Do(req)
	e.NoError(err, "failed to do request")

	return resp
}

// clean cleans predefined data or produced data from the test case.
func (s *successLoginTest) clean(e *exampleTestSuite) {
	_, err := e.db.Exec(`DELETE FROM admin WHERE id = $1`, s.id)
	e.NoError(err, "failed to delete user")
}

func (s *successLoginTest) assertLoginSuccessful(e *exampleTestSuite, resp *http.Response) {
	buf, err := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()
	e.NoError(err, "failed to read response body")

	// Do all the assertion related to the response body.
	e.NotEmpty(buf)
}

// TestSuccessLogin test case that simulate a registered user try to
// login into your app. This test case specifically test your login scenario,
// and to test that particular part means we need have a predefined data
// which is a verified account.
func (e *exampleTestSuite) TestSuccessLogin() {
	tt := new(successLoginTest)
	defer tt.clean(e)
	tt.createVerifiedUser(e)
	resp := tt.loginAPICall(e)
	tt.assertLoginSuccessful(e, resp)
}