A better version can be found at https://app.box.com/s/8zuk8yd4x9m7rbvinkb0xztz17x6xoqj This is the slide for a presentation at Golang Melbourne meetup.

1. How to not write a boring testHow to not write a boring testHow to not write a boring test
Dan TranDan TranDan Tran

2. Development and TestingDevelopment and TestingDevelopment and Testing
222

3. Test Driven DevelopmentTest Driven DevelopmentTest Driven Development
Write testWrite testWrite test
Write codeWrite codeWrite code 333

4. Unit testingUnit testingUnit testing
Table-driven testTable-driven testTable-driven test
StubStubStub
MockingMockingMocking 444

5. Table-driven testTable-driven testTable-driven test
// Gcd returns the greatest common divisor of 2 numbers.// Gcd returns the greatest common divisor of 2 numbers.// Gcd returns the greatest common divisor of 2 numbers.
func Gcd(a, b int) int {func Gcd(a, b int) int {func Gcd(a, b int) int {
if a%2 == 0 {if a%2 == 0 {if a%2 == 0 {
if b%2 == 0 {if b%2 == 0 {if b%2 == 0 {
return 2 * Gcd(a/2, b/2)return 2 * Gcd(a/2, b/2)return 2 * Gcd(a/2, b/2)
}}}
return Gcd(a/2, b)return Gcd(a/2, b)return Gcd(a/2, b)
}}}
if b%2 == 0 {if b%2 == 0 {if b%2 == 0 {
return Gcd(a, b/2)return Gcd(a, b/2)return Gcd(a, b/2)
}}}
if a == b {if a == b {if a == b {
return areturn areturn a
}}}
if a > b {if a > b {if a > b {
return Gcd(a-b, b)return Gcd(a-b, b)return Gcd(a-b, b)
}}}
return Gcd(b-a, a)return Gcd(b-a, a)return Gcd(b-a, a)
}}} Run
555

6. Table-driven test (2)Table-driven test (2)Table-driven test (2)
func TestGcd(t *testing.T) {func TestGcd(t *testing.T) {func TestGcd(t *testing.T) {
tests := []struct {tests := []struct {tests := []struct {
name stringname stringname string
args argsargs argsargs args
want intwant intwant int
}{}{}{
{{{
"Test two different numbers","Test two different numbers","Test two different numbers",
args{a: 4, b: 6},args{a: 4, b: 6},args{a: 4, b: 6},
2,2,2,
},},},
{{{
"Test two identical numbers","Test two identical numbers","Test two identical numbers",
args{a: 5, b: 5},args{a: 5, b: 5},args{a: 5, b: 5},
5,5,5,
},},},
}}}
for _, tt := range tests {for _, tt := range tests {for _, tt := range tests {
tt := tttt := tttt := tt
t.Run(tt.name, func(t *testing.T) {t.Run(tt.name, func(t *testing.T) {t.Run(tt.name, func(t *testing.T) {
if got := Gcd(tt.args.a, tt.args.b); got != tt.want {if got := Gcd(tt.args.a, tt.args.b); got != tt.want {if got := Gcd(tt.args.a, tt.args.b); got != tt.want {
t.Errorf("Gcd() = %v, want %v", got, tt.want)t.Errorf("Gcd() = %v, want %v", got, tt.want)t.Errorf("Gcd() = %v, want %v", got, tt.want)
}}}
})})})
}}}
}}} Run

7. 666

8. ExampleExampleExample
package stripepackage stripepackage stripe
// Client ...// Client ...// Client ...
// go:generate mockery -name=Client -case=underscore// go:generate mockery -name=Client -case=underscore// go:generate mockery -name=Client -case=underscore
type Client interface {type Client interface {type Client interface {
GetBalance(customerID string, currency string) (int64, error)GetBalance(customerID string, currency string) (int64, error)GetBalance(customerID string, currency string) (int64, error)
Charge(customerID string, amount int64, currency string, desc string) errorCharge(customerID string, amount int64, currency string, desc string) errorCharge(customerID string, amount int64, currency string, desc string) error
}}} Run
777

9. Stub (1)Stub (1)Stub (1)
Create an implementation which has the same set of functions as the mainCreate an implementation which has the same set of functions as the mainCreate an implementation which has the same set of functions as the main
object/class.object/class.object/class.
type stubClient struct{}type stubClient struct{}type stubClient struct{}
// GetBalance ...// GetBalance ...// GetBalance ...
func (c *stubClient) GetBalance(customerID string, currency string) (int64, error) {func (c *stubClient) GetBalance(customerID string, currency string) (int64, error) {func (c *stubClient) GetBalance(customerID string, currency string) (int64, error) {
return 100, nilreturn 100, nilreturn 100, nil
}}}
// Charge ...// Charge ...// Charge ...
func (c *stubClient) Charge(customerID string, amount int64, currency string, desc string) errorfunc (c *stubClient) Charge(customerID string, amount int64, currency string, desc string) errorfunc (c *stubClient) Charge(customerID string, amount int64, currency string, desc string) error
return nilreturn nilreturn nil
}}}
// TestGetBalanceHappyPath// TestGetBalanceHappyPath// TestGetBalanceHappyPath Run
888

10. Stub (2)Stub (2)Stub (2)
func TestGetBalanceHappyPath(t *testing.T) {func TestGetBalanceHappyPath(t *testing.T) {func TestGetBalanceHappyPath(t *testing.T) {
stripeClient = &stubClient{}stripeClient = &stubClient{}stripeClient = &stubClient{}
t.Run("Happy path", func(t *testing.T) {t.Run("Happy path", func(t *testing.T) {t.Run("Happy path", func(t *testing.T) {
got, err := GetBalance(existingCustomerID)got, err := GetBalance(existingCustomerID)got, err := GetBalance(existingCustomerID)
if err != nil {if err != nil {if err != nil {
t.Errorf("GetBalance() error = %v, wantErr %v", err, nil)t.Errorf("GetBalance() error = %v, wantErr %v", err, nil)t.Errorf("GetBalance() error = %v, wantErr %v", err, nil)
returnreturnreturn
}}}
if got != 100 {if got != 100 {if got != 100 {
t.Errorf("GetBalance() = %v, want %v", got, 100)t.Errorf("GetBalance() = %v, want %v", got, 100)t.Errorf("GetBalance() = %v, want %v", got, 100)
}}}
})})})
}}} Run
999

11. Generate mockGenerate mockGenerate mock
Using mockery: go get github.com/vektra/mockery/...Using mockery: go get github.com/vektra/mockery/...Using mockery: go get github.com/vektra/mockery/...
mockery -name=Client -case=underscoremockery -name=Client -case=underscoremockery -name=Client -case=underscore
In test leIn test leIn test le
m := mocks.Client{}m := mocks.Client{}m := mocks.Client{}
m.On("GetBalance", mock.AnythingOfType("string"), mock.AnythingOfType("string")).m.On("GetBalance", mock.AnythingOfType("string"), mock.AnythingOfType("string")).m.On("GetBalance", mock.AnythingOfType("string"), mock.AnythingOfType("string")).
Return(int64(100), nil).Once()Return(int64(100), nil).Once()Return(int64(100), nil).Once()
101010

12. MockingMockingMocking
for _, scenario := range tests {for _, scenario := range tests {for _, scenario := range tests {
scenario := scenarioscenario := scenarioscenario := scenario
t.Run(scenario.name, func(t *testing.T) {t.Run(scenario.name, func(t *testing.T) {t.Run(scenario.name, func(t *testing.T) {
m := &mocks.Client{}m := &mocks.Client{}m := &mocks.Client{}
scenario.configureMock(m)scenario.configureMock(m)scenario.configureMock(m)
stripeClient = mstripeClient = mstripeClient = m
got, err := GetBalance(scenario.userID)got, err := GetBalance(scenario.userID)got, err := GetBalance(scenario.userID)
if (err != nil) != scenario.wantErr {if (err != nil) != scenario.wantErr {if (err != nil) != scenario.wantErr {
t.Errorf("GetBalance() error = %v, wantErr %v", err, scenario.wantErr)t.Errorf("GetBalance() error = %v, wantErr %v", err, scenario.wantErr)t.Errorf("GetBalance() error = %v, wantErr %v", err, scenario.wantErr)
returnreturnreturn
}}}
if got != scenario.want {if got != scenario.want {if got != scenario.want {
t.Errorf("GetBalance() = %v, want %v", got, scenario.want)t.Errorf("GetBalance() = %v, want %v", got, scenario.want)t.Errorf("GetBalance() = %v, want %v", got, scenario.want)
returnreturnreturn
}}}
})})})
}}}
}}} Run
111111

13. Dependency InjectionDependency InjectionDependency Injection
121212

14. Monkey patchingMonkey patchingMonkey patching
In api.goIn api.goIn api.go
In api_test.goIn api_test.goIn api_test.go
originalFn := getBalanceoriginalFn := getBalanceoriginalFn := getBalance
getBalance = func(string, string)(int, error){...}getBalance = func(string, string)(int, error){...}getBalance = func(string, string)(int, error){...}
defer func() {defer func() {defer func() {
getBalance = originalFngetBalance = originalFngetBalance = originalFn
}()}()}()
var getBalance = stripeClient.GetBalancevar getBalance = stripeClient.GetBalancevar getBalance = stripeClient.GetBalance
// GetBalance2 ...// GetBalance2 ...// GetBalance2 ...
func GetBalance2(userID string) (int64, error) {func GetBalance2(userID string) (int64, error) {func GetBalance2(userID string) (int64, error) {
currency := loadCurrencyByUser(userID)currency := loadCurrencyByUser(userID)currency := loadCurrencyByUser(userID)
bal, err := getBalance(userID, currency)bal, err := getBalance(userID, currency)bal, err := getBalance(userID, currency)
if err != nil {if err != nil {if err != nil {
return 0, errreturn 0, errreturn 0, err
}}}
return bal, nilreturn bal, nilreturn bal, nil
}}} Run
131313

15. Behaviour Driven DevelopmentBehaviour Driven DevelopmentBehaviour Driven Development
141414

16. Cucumber for golangCucumber for golangCucumber for golang
Feature: get versionFeature: get versionFeature: get version
In order to know godog versionIn order to know godog versionIn order to know godog version
As an API userAs an API userAs an API user
I need to be able to request versionI need to be able to request versionI need to be able to request version
Scenario: does not allow POST methodScenario: does not allow POST methodScenario: does not allow POST method
When I send "POST" request to "/version"When I send "POST" request to "/version"When I send "POST" request to "/version"
Then the response code should be 405Then the response code should be 405Then the response code should be 405
And the response should match json:And the response should match json:And the response should match json:
"""""""""
{{{
"error": "Method not allowed""error": "Method not allowed""error": "Method not allowed"
}}}
"""""""""
Scenario: should get version numberScenario: should get version numberScenario: should get version number
When I send "GET" request to "/version"When I send "GET" request to "/version"When I send "GET" request to "/version"
Then the response code should be 200Then the response code should be 200Then the response code should be 200
And the response should match json:And the response should match json:And the response should match json:
"""""""""
{{{
"version": "v0.7.13""version": "v0.7.13""version": "v0.7.13"
}}}
""""""""" Run
151515

17. Cucumber style - GodogCucumber style - GodogCucumber style - Godog
func FeatureContext(s *godog.Suite) {func FeatureContext(s *godog.Suite) {func FeatureContext(s *godog.Suite) {
api := &apiFeature{}api := &apiFeature{}api := &apiFeature{}
s.BeforeScenario(api.resetResponse)s.BeforeScenario(api.resetResponse)s.BeforeScenario(api.resetResponse)
s.Step(`^I send "(GET|POST|PUT|DELETE)" request to "([^"]*)"$`, api.iSendrequestTo)s.Step(`^I send "(GET|POST|PUT|DELETE)" request to "([^"]*)"$`, api.iSendrequestTo)s.Step(`^I send "(GET|POST|PUT|DELETE)" request to "([^"]*)"$`, api.iSendrequestTo)
s.Step(`^the response code should be (d+)$`, api.theResponseCodeShouldBe)s.Step(`^the response code should be (d+)$`, api.theResponseCodeShouldBe)s.Step(`^the response code should be (d+)$`, api.theResponseCodeShouldBe)
s.Step(`^the response should match json:$`, api.theResponseShouldMatchJSON)s.Step(`^the response should match json:$`, api.theResponseShouldMatchJSON)s.Step(`^the response should match json:$`, api.theResponseShouldMatchJSON)
}}} Run
161616

18. Other TipsOther TipsOther Tips
Make a habit: de ne a package with interface and mockMake a habit: de ne a package with interface and mockMake a habit: de ne a package with interface and mock
What I should test: functions or behaviours. Write happy path case rst.What I should test: functions or behaviours. Write happy path case rst.What I should test: functions or behaviours. Write happy path case rst.
Consider writting tests for public funcs than private func.Consider writting tests for public funcs than private func.Consider writting tests for public funcs than private func.
Create di erent build tag for unit and integration testsCreate di erent build tag for unit and integration testsCreate di erent build tag for unit and integration tests
// +build unit// +build unit// +build unit
// +build integration// +build integration// +build integration
Disabling cache with count=1Disabling cache with count=1Disabling cache with count=1 171717

19. Test coverageTest coverageTest coverage
go test -covermode=count -coverprofile=count.outgo test -covermode=count -coverprofile=count.outgo test -covermode=count -coverprofile=count.out
go tool cover -func=count.outgo tool cover -func=count.outgo tool cover -func=count.out
181818

20. Using git pre-commit hookUsing git pre-commit hookUsing git pre-commit hook
Edit local changes in .git/hooks/pre-commitEdit local changes in .git/hooks/pre-commitEdit local changes in .git/hooks/pre-commit
Trigger go lint/test before every commitTrigger go lint/test before every commitTrigger go lint/test before every commit
#!/bin/sh#!/bin/sh#!/bin/sh
# run go lint# run go lint# run go lint
# run unit tests# run unit tests# run unit tests
go test -count=1 -short ./...go test -count=1 -short ./...go test -count=1 -short ./...
if [[ $? == 1 ]]; thenif [[ $? == 1 ]]; thenif [[ $? == 1 ]]; then
printf "unit test failed"printf "unit test failed"printf "unit test failed"
exit 1exit 1exit 1
fififi
# run integration tests# run integration tests# run integration tests
# go test --tags=integration ./...# go test --tags=integration ./...# go test --tags=integration ./...
exit 0exit 0exit 0 Run
191919

21. ResourcesResourcesResources
Demo code:Demo code:Demo code: gitlab.com/aladine/testing-demogitlab.com/aladine/testing-demogitlab.com/aladine/testing-demo(https://gitlab.com/aladine/testing-demo)(https://gitlab.com/aladine/testing-demo)(https://gitlab.com/aladine/testing-demo)
Hands-On Dependency Injection in Go, Corey Scott:Hands-On Dependency Injection in Go, Corey Scott:Hands-On Dependency Injection in Go, Corey Scott: EbookEbookEbook
(https://subscription.packtpub.com/book/application_development/9781789132762)(https://subscription.packtpub.com/book/application_development/9781789132762)(https://subscription.packtpub.com/book/application_development/9781789132762)
https://github.com/DATA-DOG/godoghttps://github.com/DATA-DOG/godoghttps://github.com/DATA-DOG/godog
Arts icon byArts icon byArts icon by twitter.com/deniseyu21twitter.com/deniseyu21twitter.com/deniseyu21(https://twitter.com/deniseyu21)(https://twitter.com/deniseyu21)(https://twitter.com/deniseyu21)
202020

22. Hiring - OpenSimSimHiring - OpenSimSimHiring - OpenSimSim
We are hiring golang developers and devops engineers.We are hiring golang developers and devops engineers.We are hiring golang developers and devops engineers. 212121

23. Thank youThank youThank you
Dan TranDan TranDan Tran
@trongdan_tran@trongdan_tran@trongdan_tran(http://twitter.com/trongdan_tran)(http://twitter.com/trongdan_tran)(http://twitter.com/trongdan_tran)
Senior Software Developer atSenior Software Developer atSenior Software Developer at OpensimsimOpensimsimOpensimsim(https://opensimsim.com/)(https://opensimsim.com/)(https://opensimsim.com/)