Chcąc zapewnić poprawną współpracę mikroserwisów, wpadamy często w pułapkę testów, którym nie ufamy lub które są zbyt trudne w utrzymaniu. Testy kontraktowe to alternatywne podejście oferujące z jednej strony szybką informację zwrotną a z drugiej strony poziom pewności niedostępny dla testów izolowanych. To nie jedyne korzyści: z ich wykorzystaniem możemy przyspieszyć nasz cykl pracy oraz lepiej zrozumieć, jak połączone są nasze systemy. W trakcie prezentacji zobaczymy minimalny działający przykład napisany w Kotlinie przy użyciu frameworku Pact, prześledzimy, co możemy zyskać w zależności od nakładu pracy oraz spojrzymy szerzej na ekosystem testów kontraktowych, porównując Pact z biblioteką Spring Cloud Contract. Slajdy z prezentacji na konferencji DynamIT 2019.

1. FLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTOFLYING STARTINTO
CONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTINGCONTRACTTESTING
Piotr Kubowicz
 @pkubowicz

2. $ whois piotr-kubowicz
Java/JVM since 2007
pact-jvm contributor 

4. Planner app
How many forklifts to move
supplies arriving tomorrow?
Supplies system
tomorrow: 300 apples,
45 kg
tomorrow: 40 bottles of
water, 60 kg
+2 days: 600 carrots,
36 kg

5. TESTING WITHREAL DEPENDENCIES
('integration testing')

6. MOCKING DEPENDENCIES
Planner Supplies
Planner tests
Planner Fake Supplies
Supplies tests
Fake Planner Supplies

7. TYPICAL PROBLEM
{
"count": 15,
"status": "CANCELED"
}
{
"count": 15,
"status": "CANCELLED"
}

8. CONTRACTTESTING
Planner Contract Supplies
enforced in an automatic way

9. TERMINOLOGY
Planner Supplies
REST call
Consumer Provider

10. LET'S SEEITWORKING

11. SPEED
Consumer: 220 test cases per minute
Provider: 2400 test cases per minute

12. PACTWORKFLOW
1. Consumer test
2. Play with API
3. Share contract
4. Adopt Provider

13. PACTWORKFLOW
No waiting until Provider features are ready
You can start without Provider itself

14. SHARING PACTCONTRACTS
Attach to an e-mail then commit to Git
Publish to your artifact repository (Maven)
Dedicated Pact Broker server

15. PACTBROKER

16. PACTBROKER

18. LANGUAGES SUPPORTED
JVM
JS
Ruby
.NET
Go
Swift
PHP
any (for provider)

19. PACT ONTHE PROVIDER SIDE
Pact Provider
Verifier Your Provider
Docker any language

20. PACTONTHEPROVIDER SIDE
Planner Shop
Supplies

21. CONTRACTTESTS USECASES
teams in different locations
backend-frontend in one team
message queues

22. ALTERNATIVETOOLS
Spring Cloud Contract

23. Consumer test
Contract
Provider test
Provider test
Stubs
Consumer test
Contract

24. Provider test
Stubs
Consumer test
Contract
Gradle/Maven
JUnit 4/5
Spock
Maven repo
Stub runner
Groovy

25. Provider test
Stubs
Consumer test
Contract
Docker
Maven repo/Git
Docker
YAML

26. CONTRACTINSPRING CLOUDCONTRACT
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
url('/supplies') {
queryParameters {
parameter day: '2018-12-23'
}
}
}
response {
status OK()
body([status: "CANCELED"])
headers { contentType('application/json') }
}
}

27. Generated test
Base class you need to write
public class ManySuppliesTest extends ContractVerifierBase {
@Test
public void validate_returnsManySupplies() throws Exception {
Response response = given().spec(request)
.queryParam("day","2018-12-23").get("/supplies");
// ...
assertThatJson(parsedJson).array()
.contains("['status']").isEqualTo("CANCELED");
abstract class ContractVerifierBase {
@Before
fun startServer() {
RestAssured.port = 9053
MyServer().start(9053)
}

28. QUIRKS
Accepts 3 items
response {
body([
[status: "CANCELED"],
[count: 4, totalWeight: 20, status: "ACTIVE"],
])
}
[
{"status": "CANCELED"},
{"count": 4, "totalWeight": 20, "status": "ACTIVE"},
{"count": 151, "totalWeight": 980, "status": "ACTIVE"}
]

29. QUIRKS
Accepted response
response {
body([
[status: "CANCELED"],
[count: 4, totalWeight: 20, status: "ACTIVE"],
])
}
[
{"count": 4, "totalWeight": 980, "status": "CANCELED"},
{"count": 151, "totalWeight": 20, "status": "ACTIVE"}
]

30. Spring Cloud Contract can work with Pact contracts

32. NO TIMEFOR THIS —I'MTOO BUSY
writing tests for code sending HTTP requests
asking other team what data they expect
thinking about edge cases
testing my DB queries return what I want

33. CONTRACTTESTS
test correct form of Consumer requests
document requests/responses
share test data and edge cases
verify full stack of Provider

34. THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!THANK YOU!

35. ATTRIBUTION
Photo by on Unsplash
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Question mark icon by
dylan nolte
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36. Q & A
Twitter
piotr.kubowicz@gmail.com
@pkubowicz
github.com/pkubowicz/contract-testing-samples
pact.io
cloud.spring.io/spring-cloud-contract/