Micro-services are the new black; everyone is using them. Alas, when your system is composed of many micro-services, testing becomes more challenging. The straight-forward approach for E2E testing no longer suffices and for integration tests it doesn’t even exist. A better way to test in this kind of an environment would be to work with a test kit of the micro-service you are interacting with. By the end of this talk, you will learn how to create a test-kit that covers your micro-service. Testing this way will grant you a much higher level of confidence, and will portray a more accurate picture of your assumptions vs. reality. Overall it will make any integration between micro-services easier, thus benefit your colleagues and make your company progress faster.

1. A Better Approach for Testing Micro-Services
Introducing: Test Kits in Practice
Maxim Novak, Wix Back-end
https://github.com/maximn@maximnovakmaximn@wix.com

2. With Wix you can create a stunning website.

3. I’m Maxim Novak
▪ Team leader at Wix
▪ Building core services
▪ 10 years developing software
▪ TDD and clean code enthusiast
Lithuania
Vilnius
Kyiv
Dnipro
Wix Engineering Locations
Israel
Tel-Aviv
Be’er Sheva
Ukraine

4. AGENDA
Why testing in a microservices
architecture is challenging
How to approach these
challenges

5. Why testing in a microservices
architecture is challenging
01

6. MONOLITH In the old world,
testing was
simple.

12. http://3gamma.com/insights/architecting-speed-agile-innovators-accelerate-growth-microservices/
You start
like this...

13. https://www.slideshare.net/BruceWong3/the-case-for-chaos https://twitter.com/adrianco/status/441883572618948608
...and end up
like this.
NETFLIX TWITTER

14. Testing with microservices
is challenging.
You still want...
❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)

15. RECAP
How we Test

16. MY APP
STORE
SESSION
(USER ID)
USERS
SERVER
NAME IN THE
CONFIRMATION
PAGE
Example
Scenario

17. SESSION
(USER ID)
CONFIRMATION
PAGE WITH
NAME
Recap
End to End
(Out-of-process
component tests)
MY APP
STORE
?
TEST

18. Recap
Integration Tests
MY APP
STORE
USER ID
?
TEST
NAME
USERS
CLIENT

19. How to
approach it
02

20. #0
Don’t test
(the integration)
NOT
REALLY,
RIGHT?
OUR
MICRO
SERVICE

21. MY APP
STORE
TEST
USERS
CLIENT
STUB
USERS
CLIENT
Users
SERVER
SESSION
(USER ID)
CONFIRMATION
PAGE WITH
NAME

22. MY APP
STORE
if (isTestMode) {
// ...
}
else {
// ...
}
TEST
USERS
CLIENT
STUB
USERS
CLIENT
SESSION
(USER ID)
CONFIRMATION
PAGE WITH
NAME
Users
SERVER

23. The real
implementation
is never tested
(well … only in
production)
MY APP
STORE
TEST
STUB
USERS
CLIENT
SESSION
(USER ID)
CONFIRMATION
PAGE WITH
NAME
Users
SERVERUSERS
CLIENT

24. You DO want an “out of process
component tests” (e2e).

26. ❏E2E
❏Integration
✘
✘
#0
Don’t test
(the integration)
OUR
MICRO
SERVICE

27. OUR
MICRO
SERVICE
#1
Run against an
external environment

28. USERS
SERVER
MY APP
STORE
SESSION
(USER ID)
TEST
CONFIRMATION
PAGE WITH
NAME

29. ❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)
✘
BEHAVES AS
WE ASSUME ✔
#1
Run against an
external environment

30. ❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)
✘
ENSURE
COMMUNICATION
PROTOCOL &
SCHEMA
✔
#1
Run against an
external environment

31. Running against external environment is
unreliable. It has a high maintenance
cost and it adds complexity to your app.

32. #1
Run against an
external environment
OUR
MICRO
SERVICE
❏E2E
❏Integration
✘
✘

33. #2
Use test
doubles
STUB
FAKE
MOCK
OUR
MICRO
SERVICE
https://martinfowler.com/articles
/mocksArentStubs.html
HTTP

34. FAKE
USERS SERVER
MY APP
STORE
SESSION
(USER ID)
TEST
NAME IN THE
CONFIRMATION
PAGE

35. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#2
Use test
doubles
E2E
example

36. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#2
Use test
doubles
E2E
example

37. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#2
Use test
doubles
E2E
example

38. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#2
Use test
doubles
E2E
example

39. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#2
Use test
doubles
IT success
example

40. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#2
Use test
doubles
IT success
example

41. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#2
Use test
doubles
IT success
example

42. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
fakeUsersServer.givenUser(userId, name);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#2
Use test
doubles
IT success
example

43. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
UUID userId = UUID.randomUUID();
fakeUsersServer.givenUserNotFound(userId);
usersClient.getName(userId);
}
#2
Use test
doubles
IT failure
example

44. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
UUID userId = UUID.randomUUID();
fakeUsersServer.givenUserNotFound(userId);
usersClient.getName(userId);
}
#2
Use test
doubles
IT failure
example

45. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
UUID userId = UUID.randomUUID();
fakeUsersServer.givenUserNotFound(userId);
usersClient.getName(userId);
}
#2
Use test
doubles
IT failure
example

46. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
UUID userId = UUID.randomUUID();
fakeUsersServer.givenUserNotFound(userId);
usersClient.getName(userId);
}
#2
Use test
doubles
IT failure
example

47. #2
Use test
doubles
❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)
✔

48. #2
Use test
doubles
❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)
✔
✔✘
WE IMPLEMENT THE
TEST DOUBLE IN A
WAY WE ASSUME IT
WORKS - NOT HOW IT
WORKS IN REALITY

49. #2
Use test
doubles
CONSUMER
CONSUMER
CONSUMER
CONSUMER
CONSUMER
CONSUMER
...AND, ALL OUR CONSUMERS
WILL HAVE TO IMPLEMENT
THEM TOO
SERVICE
PROVIDER

50. ❏E2E
❏Integration
#2
Use test
doubles
STUB
FAKE
MOCK
✔✘OUR
MICRO
SERVICE
✔

51. We can do
better.
HAVE A MUCH
HIGHER LEVEL
OF CONFIDENCE
❏ A short and reliable
feedback loop
❏ To test assumptions vs.
reality (logic/protocol)
✔
✔

52. A lightweight version
of the real thing.
OUR
MICRO
SERVICE
#3
Test Kit from
Service Provider

53. USERS
TESTKIT
MY APP
STORE
SESSION
(USER ID)
TEST
NAME IN THE
CONFIRMATION
PAGE

54. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
User user = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(user);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#3
Test kits
E2E
example

55. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
User user = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(user);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#3
Test kits
E2E
example

56. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
User user = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(user);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#3
Test kits
E2E
example

57. @Test
public void purchase_e2e() {
UUID userId = UUID.randomUUID();
String name = someName();
User user = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(user);
login(userId);
addItemToCart(itemId);
ConfirmationPage confirmationPage = purchase();
assertThat(confirmationPage, containsName(name));
}
#3
Test kits
E2E
example

58. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
User givenUser = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(givenUser);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#3
Test kits
IT success
example

59. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
User givenUser = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(givenUser);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#3
Test kits
IT success
example

60. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
User givenUser = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(givenUser);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#3
Test kits
IT success
example

61. @Test
public void getName_success() {
UUID userId = UUID.randomUUID();
String name = someName();
User givenUser = new UsersTestBuilder()
.withId(userId)
.withName(name)
.build();
usersTestkit.givenUser(givenUser);
String result = usersClient.getName(userId);
assertEquals(name, result);
}
#3
Test kits
IT success
example

62. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
usersClient.getName(UUID.randomUUID());
}
#3
Test kits
IT failure
example

63. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
usersClient.getName(UUID.randomUUID());
}
#3
Test kits
IT failure
example

64. @Test(expected = UserNotFoundException.class)
public void getName_notFound() {
usersClient.getName(UUID.randomUUID());
}
#3
Test kits
IT failure
example

65. public class UsersTestkit {
public void start(int port) {
...
}
public void stop() {
...
}
...
What the
consumer
gets?

66. public class UsersTestkit {
...
public void givenUser(User user) {
...
}
public void updateUser(UUID userId,
UserUpdate user) {
...
}
}
What the
consumer
gets?

67. How to build a testkit?
OUR
MICRO
SERVICE

68. Test
doubles
Real
thing
Test kits

69. You’re able to
communicate with
your consumers
Other services
Use test doubles
Database
Implement in-memory version
Cross-test with the real
implementation
WHEN SOMETHING
CHANGES - THEY KNOW
ABOUT IT
OUR
MICRO
SERVICE

70. What about next level
dependencies?
Other services
Use test doubles
Database
Implement in-memory version
Cross-test with the real
implementation
OUR TESTKIT WON’T
BRING MORE LEVELS
IN THE CHAIN OF
SERVICES!
OUR
MICRO
SERVICE

71. Integration Contract
Test
We want to make sure that our
testkit behaves like the real thing
OUR
MICRO
SERVICE
https://martinfowler.com/bliki
/IntegrationContractTest.html

72. INTEGRATION
CONTRACT TEST
USERS
TESTKIT
USERS
SERVER
In Memory DAO MySLQ DAO

73. USERS
SERVER
INTEGRATION
CONTRACT TEST
USERS
TESTKIT
MY APP
STORE
SESSION
(USER ID)
NAME IN THE
CONFIRMATION
PAGE
TEST

74. Disadvantages
➜ More development
➜ Build dependency (on
implementation)
#3
Test kits OUR
MICRO
SERVICE

75. #3
Test kits
OUR
MICRO
SERVICE
❏E2E
❏Integration
✔
✔

76. Thank You
https://github.com/maximn@maximnovakmaximn@wix.com