REST and Messaging solutions do not come with an in-built contract compliance mechanism, which in many ways is a great thing. However, while working with microservice-based systems, it often appears that a practical mechanism that would help in designing and verifying REST and Messaging APIs would come in handy. Similarly, creating integration and acceptance tests in such systems presents many challenges. At Devskiller we use Spring Cloud Contract in order to easily develop, test and document the APIs. During this talk I will show how we leverage this tool to design the contracts, quickly generate automatically-tested stubs from simple Groovy DSL scripts and, subsequently, generate the documentation, and how using Spring Cloud Contract allows us to build reliable microservice-based solutions, at the same time reducing the amount of E2E tests we run and the time necessary to deploy our apps to a minimum.

1. Testing REST &Testing REST &
Messaging applicationsMessaging applications
at Devskiller - a caseat Devskiller - a case
studystudy
@olga_maciaszek
Olga Maciaszek-Sharma
14.05.2018

2. Olga Maciaszek-SharmaOlga Maciaszek-Sharma
@olga_maciaszek
https://github.com/OlgaMaciaszekhttps://github.com/OlgaMaciaszek
@@olga_maciaszekolga_maciaszek

3. BackgroundBackground
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4. E2E TestsE2E Tests

5. E2E TestsE2E Tests
@olga_maciaszek

6. @olga_maciaszek
Source: https://testing.googleblog.com/2015/04/just-say-no-to-more-end-to-end-tests.html
Test PyramidTest Pyramid

7. MicroservicesMicroservices
@olga_maciaszek

8. Decoupling DeploymentDecoupling Deployment
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Environment per ServiceEnvironment per Service
One To Rule Them AllOne To Rule Them All

9. FailsafeFailsafe
vs.vs.
Safe To FailSafe To Fail
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10. Circuit BreakersCircuit Breakers
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11. How many E2E?How many E2E?
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12. ContractsContracts
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MonitoringMonitoring
AlertingAlerting
LoggingLogging
Unit TestsUnit Tests

13. Input A ==> Output BInput A ==> Output B
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ContractsContracts

14. Consumer-Driven ContractsConsumer-Driven Contracts
sinon.jssinon.js
https://martinfowler.com/articles/consum
erDrivenContracts.html
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15. Contract TestsContract Tests
https://martinfowler.com/bliki/ContractTest.html
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16. Spring Cloud ContractSpring Cloud Contract
https://cloud.spring.io/spring-cloud-contract/
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17. ContractsContracts
package contracts
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'PUT'
url '/fraudcheck'
body([
"client.id": $(regex('[0-9]{10}')),
loanAmount: 99999
])
headers {
contentType('application/json')
}
}
response {
status OK()
body([
fraudCheckStatus: "FRAUD",
"rejection.reason": "Amount too high"
])
headers {
contentType('application/json')
}
}
}
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18. Contract TestsContract Tests
@Test
public void validate_shouldMarkClientAsFraud() throws Exception {
// given:
MockMvcRequestSpecification request = given()
.header("Content-Type", "application/vnd.fraud.v1+json")
.body("{"client.id":"1234567890","loanAmount":99999}");
// when:
ResponseOptions response = given().spec(request)
.put("/fraudcheck");
// then:
assertThat(response.statusCode()).isEqualTo(200);
assertThat(response.header("Content-Type"))
.matches("application/vnd.fraud.v1.json.*");
// and:
DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
assertThatJson(parsedJson).field("['fraudCheckStatus']").matches("[A-Z]{5}");
assertThatJson(parsedJson).field("['rejection.reason']")
.isEqualTo("Amount too high");
}
@olga_maciaszek

19. Contract TestsContract Tests
def validate_shouldMarkClientAsFraud() {
given:
def request = given()
.header('Content-Type', 'application/vnd.fraud.v1+json')
.body('{"clientId":"12345678902","loanAmount":99999}')
when:
def response = given().spec(request).put("/fraudcheck")
then:
response.statusCode == 200
response.header('Content-Type') == 'application/vnd.fraud.v1+json'
and:
DocumentContext parsedJson = JsonPath.parse(response.body.asString())
assertTassertThatJson(parsedJson).field("rejectionReason")
.isEqualTo("Amount too high")
assertThatJson(parsedJson).field("fraudCheckStatus").isEqualTo("FRAUD")
}
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20. StubsStubs
{
"request": {
"url": "/fraudcheck",
"method": "PUT",
"bodyPatterns": [
{
"matchesJsonPath": "$[?(@.loanAmount == 99999)]"
},
{
"matchesJsonPath": "$[?(@.clientId == '12345678902')]"
}
],
"headers": {
"Content-Type": {
"equalTo": "application/vnd.fraud.v1+json"
}
}
},
"response": {
"status": 200,
"body": "{"fraudCheckStatus":"FRAUD",
"rejectionReason":"Amount too high"}",
"headers": {
"Content-Type": "application/vnd.fraud.v1+json"
}
}
}
@olga_maciaszek

21. Using StubsUsing Stubs
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"},
stubsMode = StubRunnerProperties.StubsMode.LOCAL)
@DirtiesContext
public class LoanApplicationServiceTests { ... }
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JUnit Rule
Service Discovery

22. Messaging ContractsMessaging Contracts
def contractDsl = Contract.make {
label 'some_label'
input {
messageFrom('inputQueue')
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo('outputQueue')
body([
bookName: 'foo'
])
headers {
header('BOOK-NAME', 'foo')
}
}
}
@olga_maciaszek

23. Messaging Contract TestsMessaging Contract Tests
given:
ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
'''{"bookName":"foo"}''',
['sample': 'header']
)
when:
contractVerifierMessaging.send(inputMessage, 'inputQueue')
then:
ContractVerifierMessage response = contractVerifierMessaging
.receive('outputQueue')
assert response != null
response.getHeader('BOOK-NAME')?.toString() == 'foo'
and:
DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper
.writeValueAsString(response.payload))
assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
@olga_maciaszek

24. Messaging Client-Side TestMessaging Client-Side Test
given:
messaging.send(new BookReturned('foo'), [sample: 'header'], 'input')
when:
Message<?> receivedMessage = messaging.receive('outputTest')
then:
receivedMessage != null
assertJsons(receivedMessage.payload)
receivedMessage.headers.get('BOOK-NAME') == 'foo'
@olga_maciaszek

25. StubTrigger InterfaceStubTrigger Interface
package org.springframework.cloud.contract.stubrunner;
import java.util.Collection;
import java.util.Map;
public interface StubTrigger {
boolean trigger(String ivyNotation, String labelName);
boolean trigger(String labelName);
boolean trigger();
Map<String, Collection<String>> labels();
}
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26. SCC Canonical FlowSCC Canonical Flow
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27. SCC Canonical FlowSCC Canonical Flow
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28. SCC Canonical FlowSCC Canonical Flow
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29. SCC Canonical FlowSCC Canonical Flow
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30. SCC Canonical FlowSCC Canonical Flow
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31. Local FlowLocal Flow
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Sources: http://blog.cleancoder.com/uncle-bob/2014/12/17/TheCyclesOfTDD.html

32. Local FlowLocal Flow
Skip Test To Generate Stubs
Stub service layer implementation while working on the
API
Never skip tests in the pipelines
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33. Contracts ScopeContracts Scope
Skip Contracts for non-Skip Contracts for non-
essential functionalityessential functionality
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34. Contracts ScopeContracts Scope
Skip multiple valuesSkip multiple values
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35. Skip Multiple ValuesSkip Multiple Values
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request {
method 'PUT'
url '/fraudcheck'
body([
"client.id": $(regex('[0-9]{10}')),
"client.type" : "INDIVIDUAL"
loanAmount: 99999
])
headers {
contentType('application/json')
}}
request {
method 'PUT'
url '/fraudcheck'
body([
"client.id": $(regex('[0-9]{10}')),
"client.type" : "BUSINESS"
loanAmount: 99999
])
headers {
contentType('application/json')
}}

36. BackwardsBackwards
Compatibility CheckCompatibility Check
Spring Cloud PipelinesSpring Cloud Pipelines
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37. BackwardsBackwards
Compatibility ChangeCompatibility Change
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Contracts APP
Deferred UpdateDeferred Update
bT bT
bT + bTM bT + bTM
bTM bT + bTM
bTM bTM

38. No Shared DTOsNo Shared DTOs
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39. SNAPSHOTSSNAPSHOTS
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40. Public APIPublic API
Spring Rest DocsSpring Rest Docs
MockMvc Tests -> REST Docs, Stubs, Contracts
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41. Public APIPublic API
mvn spring-cloud-contract:run -Dstubs="org.springframework:gs-rest-service"
Docs
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42. Generate Rest DocsGenerate Rest Docs
from Contractsfrom Contracts
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43. https://github.com/OlgaMaciaszekhttps://github.com/OlgaMaciaszek
@@olga_maciaszekolga_maciaszek
Thank youThank you