What you always need is confidence in pushing new features into a new application or service in a distributed system. This project provides support for Consumer Driven Contracts and service schemas in Spring applications, covering a range of options for writing tests, publishing them as assets, asserting that a contract is kept by producers and consumers, for HTTP and message-based interactions.
If you prefer to learn about the project by doing some tutorials you can check out the workshops under this link.
|
Tip
|
The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski (codearte.io) |
Just to make long story short - Spring Cloud Contract Verifier is a tool that enables Consumer Driven Contract (CDC) development of JVM-based applications. It is shipped with Contract Definition Language (DSL). Contract definitions are used to produce following resources:
-
JSON stub definitions to be used by WireMock when doing integration testing on the client code (client tests). Test code must still be written by hand, test data is produced by Spring Cloud Contract Verifier.
-
Messaging routes if you’re using one. We’re integrating with Spring Integration, Spring Cloud Stream, Spring AMQP and Apache Camel. You can however set your own integrations if you want to
-
Acceptance tests (in JUnit or Spock) used to verify if server-side implementation of the API is compliant with the contract (server tests). Full test is generated by Spring Cloud Contract Verifier.
Spring Cloud Contract Verifier moves TDD to the level of software architecture.
Let us assume that we have a system comprising of multiple microservices:
If we wanted to test the application in top left corner if it can communicate with other services then we could do one of two things:
-
deploy all microservices and perform end to end tests
-
mock other microservices in unit / integration tests
Both have their advantages but also a lot of disadvantages. Let’s focus on the latter.
Deploy all microservices and perform end to end tests
Advantages:
-
simulates production
-
tests real communication between services
Disadvantages:
-
to test one microservice we would have to deploy 6 microservices, a couple of databases etc.
-
the environment where the tests would be conducted would be locked for a single suite of tests (i.e. nobody else would be able to run the tests in the meantime).
-
long to run
-
very late feedback
-
extremely hard to debug
Mock other microservices in unit / integration tests
Advantages:
-
very fast feedback
-
no infrastructure requirements
Disadvantages:
-
the implementor of the service creates stubs thus they might have nothing to do with the reality
-
you can go to production with passing tests and failing production
To solve the aforementioned issues Spring Cloud Contract Verifier with Stub Runner were created. Their main idea is to give you very fast feedback, without the need to set up the whole world of microservices. If you work on stubs then the only applications you need are those that your application is using directly.
Spring Cloud Contract Verifier gives you the certainty that the stubs that you’re using were created by the service that you’re calling. Also if you can use them it means that they were tested against the producer’s side. In other words - you can trust those stubs.
The main purposes of Spring Cloud Contract Verifier with Stub Runner are:
-
to ensure that WireMock / Messaging stubs (used when developing the client) are doing exactly what actual server-side implementation will do,
-
to promote ATDD method and Microservices architectural style,
-
to provide a way to publish changes in contracts that are immediately visible on both sides,
-
to generate boilerplate test code used on the server side.
|
Important
|
Spring Cloud Contract Verifier’s purpose is NOT to start writing business features in the contracts. Let’s assume that we have a business use case of fraud check. If a user can be a fraud for 100 different reasons, we would assume that you would create 2 contracts. One for the positive and one for the negative fraud case. Contract tests are used to test contracts between applications and not to simulate full behaviour. |
As consumers we need to define what exactly we want to achieve. We need to formulate our expectations. That’s why we write the following contract.
Let’s assume that we’d like to send the request containing the id of the client and the amount he wants to borrow from us. We’d like to send it to the /fraudcheck url via the PUT method.
package contracts
org.springframework.cloud.contract.spec.Contract.make {
request { // (1)
method 'PUT' // (2)
url '/fraudcheck' // (3)
body([ // (4)
"client.id": $(regex('[0-9]{10}')),
loanAmount: 99999
])
headers { // (5)
contentType('application/json')
}
}
response { // (6)
status 200 // (7)
body([ // (8)
fraudCheckStatus: "FRAUD",
"rejection.reason": "Amount too high"
])
headers { // (9)
contentType('application/json')
}
}
}
/*
From the Consumer perspective, when shooting a request in the integration test:
(1) - If the consumer sends a request
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/json`
(6) - then the response will be sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` equal to `application/json`
From the Producer perspective, in the autogenerated producer-side test:
(1) - A request will be sent to the producer
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that will have a generated value that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/json`
(6) - then the test will assert if the response has been sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` matching `application/json.*`
*/Spring Cloud Contract will generate stubs, which you can use during client side testing. You will have a WireMock instance / Messaging route up and running that simulates the service Y. You would like to feed that instance with a proper stub definition.
At some point in time you need to send a request to the Fraud Detection service.
ResponseEntity<FraudServiceResponse> response =
restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
new HttpEntity<>(request, httpHeaders),
FraudServiceResponse.class);Annotate your test class with @AutoConfigureStubRunner. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators.
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
@DirtiesContext
public class LoanApplicationServiceTests {After that, during the tests Spring Cloud Contract will automatically find the stubs (simulating the real service) in Maven repository and expose them on configured (or random) port.
Being a service Y since you are developing your stub, you need to be sure that it’s actually resembling your concrete implementation. You can’t have a situation where your stub acts in one way and your application on production behaves in a different way.
That’s why from the provided stub acceptance tests will be generated that will ensure that your application behaves in the same way as you define in your stub.
The autogenerated test would look like this:
@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");
}Let’s take an example of Fraud Detection and Loan Issuance process. The business scenario is such that we want to issue loans to people but don’t want them to steal the money from us. The current implementation of our system grants loans to everybody.
Let’s assume that the Loan Issuance is a client to the
Fraud Detection server. In the current sprint we are required to develop a new feature - if a client wants to borrow too much money then we mark him as fraud.
Technical remark - Fraud Detection will have artifact id http-server, Loan Issuance http-client and both have group id com.example.
Social remark - both client and server development teams need to communicate directly and discuss changes while going through the process. CDC is all about communication.
|
Tip
|
In this case the ownership of the contracts lays on the producer side. It means that physically all the contract are present in the producer’s repository |
If using the SNAPSHOT / Milestone / Release Candidate versions please add the following section to your
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>repositories {
mavenCentral()
mavenLocal()
maven { url "http://repo.spring.io/snapshot" }
maven { url "http://repo.spring.io/milestone" }
maven { url "http://repo.spring.io/release" }
}As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):
start doing TDD by writing a test to your feature
@Test
public void shouldBeRejectedDueToAbnormalLoanAmount() {
// given:
LoanApplication application = new LoanApplication(new Client("1234567890"),
99999);
// when:
LoanApplicationResult loanApplication = service.loanApplication(application);
// then:
assertThat(loanApplication.getLoanApplicationStatus())
.isEqualTo(LoanApplicationStatus.LOAN_APPLICATION_REJECTED);
assertThat(loanApplication.getRejectionReason()).isEqualTo("Amount too high");
}We’ve just written a test of our new feature. If a loan application for a big amount is received we should reject that loan application with some description.
write the missing implementation
At some point in time you need to send a request to the Fraud Detection service. Let’s assume that we’d like to send the request containing the id of the client and the amount he wants to borrow from us. We’d like to send it to the /fraudcheck url via the PUT method.
ResponseEntity<FraudServiceResponse> response =
restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
new HttpEntity<>(request, httpHeaders),
FraudServiceResponse.class);For simplicity we’ve hardcoded the port of the Fraud Detection service at 8080 and our application is running on 8090.
If we’d start the written test it would obviously break since we have no service running on port 8080.
clone the Fraud Detection service repository locally
We’ll start playing around with the server side contract. That’s why we need to first clone it.
git clone https://your-git-server.com/server-side.git local-http-server-repodefine the contract locally in the repo of Fraud Detection service
As consumers we need to define what exactly we want to achieve. We need to formulate our expectations. That’s why we write the following contract.
|
Important
|
We’re placing the contract under src/test/resources/contract/fraud folder. The fraud folder
is important cause we’ll reference that folder in the producer’s test base class name.
|
package contracts
org.springframework.cloud.contract.spec.Contract.make {
request { // (1)
method 'PUT' // (2)
url '/fraudcheck' // (3)
body([ // (4)
"client.id": $(regex('[0-9]{10}')),
loanAmount: 99999
])
headers { // (5)
contentType('application/json')
}
}
response { // (6)
status 200 // (7)
body([ // (8)
fraudCheckStatus: "FRAUD",
"rejection.reason": "Amount too high"
])
headers { // (9)
contentType('application/json')
}
}
}
/*
From the Consumer perspective, when shooting a request in the integration test:
(1) - If the consumer sends a request
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/json`
(6) - then the response will be sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` equal to `application/json`
From the Producer perspective, in the autogenerated producer-side test:
(1) - A request will be sent to the producer
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that will have a generated value that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/json`
(6) - then the test will assert if the response has been sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` matching `application/json.*`
*/The Contract is written using a statically typed Groovy DSL. You might be wondering what are those
value(client(…), server(…)) parts. By using this notation Spring Cloud Contract allows you to
define parts of a JSON / URL / etc. which are dynamic. In case of an identifier or a timestamp you
don’t want to hardcode a value. You want to allow some different ranges of values. That’s why for
the consumer side you can set regular expressions matching those values. You can provide the body
either by means of a map notation or String with interpolations.
Consult the docs
for more information. We highly recommend using the map notation!
|
Tip
|
It’s really important that you understand the map notation to set up contracts. Please read the Groovy docs regarding JSON |
The aforementioned contract is an agreement between two sides that:
-
if an HTTP request is sent with
-
a method
PUTon an endpoint/fraudcheck -
JSON body with
client.idmatching the regular expression[0-9]{10}andloanAmountequal to99999 -
and with a header
Content-Typeequal toapplication/vnd.fraud.v1+json
-
-
then an HTTP response would be sent to the consumer that
-
has status
200 -
contains JSON body with the
fraudCheckStatusfield containing a valueFRAUDand therejectionReasonfield having valueAmount too high -
and a
Content-Typeheader with a value ofapplication/vnd.fraud.v1+json
-
Once we’re ready to check the API in practice in the integration tests we need to just install the stubs locally
add the Spring Cloud Contract Verifier plugin
We can add either Maven or Gradle plugin - in this example we’ll show how to add Maven. First we need to add the Spring Cloud Contract BOM.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>Next, the Spring Cloud Contract Verifier Maven plugin
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
</configuration>
</plugin>Since the plugin was added we get the Spring Cloud Contract Verifier features which from the provided contracts:
-
generate and run tests
-
produce and install stubs
We don’t want to generate tests since we, as consumers, want only to play with the stubs. That’s why we need to skip the tests generation and execution. When we execute:
cd local-http-server-repo
./mvnw clean install -DskipTestsIn the logs we’ll see something like this:
[INFO] --- spring-cloud-contract-maven-plugin:1.0.0.BUILD-SNAPSHOT:generateStubs (default-generateStubs) @ http-server ---
[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar
[INFO]
[INFO] --- maven-jar-plugin:2.6:jar (default-jar) @ http-server ---
[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar
[INFO]
[INFO] --- spring-boot-maven-plugin:1.5.4.BUILD-SNAPSHOT:repackage (default) @ http-server ---
[INFO]
[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ http-server ---
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.jar
[INFO] Installing /some/path/http-server/pom.xml to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.pom
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jarThis line is extremely important
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jarIt’s confirming that the stubs of the http-server have been installed in the local repository.
run the integration tests
In order to profit from the Spring Cloud Contract Stub Runner functionality of automatic stub downloading you have to do the following in our consumer side project (Loan Application service).
Add the Spring Cloud Contract BOM
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>Add the dependency to Spring Cloud Contract Stub Runner
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
<scope>test</scope>
</dependency>Annotate your test class with @AutoConfigureStubRunner. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators. Also provide the offline work switch since you’re playing with the collaborators offline (optional step).
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
@DirtiesContext
public class LoanApplicationServiceTests {Now if you run your tests you’ll see sth like this:
2016-07-19 14:22:25.403 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Desired version is + - will try to resolve the latest version
2016-07-19 14:22:25.438 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved version is 0.0.1-SNAPSHOT
2016-07-19 14:22:25.439 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolving artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT using remote repositories []
2016-07-19 14:22:25.451 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
2016-07-19 14:22:25.465 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacking stub from JAR [URI: file:/path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar]
2016-07-19 14:22:25.475 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacked file to [/var/folders/0p/xwq47sq106x1_g3dtv6qfm940000gq/T/contracts100276532569594265]
2016-07-19 14:22:27.737 INFO 41050 --- [ main] o.s.c.c.stubrunner.StubRunnerExecutor : All stubs are now running RunningStubs [namesAndPorts={com.example:http-server:0.0.1-SNAPSHOT:stubs=8080}]Which means that Stub Runner has found your stubs and started a server for app with group id com.example, artifact id http-server with version 0.0.1-SNAPSHOT of the stubs and with stubs classifier on port 8080.
file a PR
What we did until now is an iterative process. We can play around with the contract, install it locally and work on the consumer side until we’re happy with the contract.
Once we’re satisfied with the results and the test passes publish a PR to the server side. Currently the consumer side work is done.
As a developer of the Fraud Detection server (a server to the Loan Issuance service):
initial implementation
As a reminder here you can see the initial implementation
@RequestMapping(value = "/fraudcheck", method = PUT)
public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
}take over the PR
git checkout -b contract-change-pr master
git pull https://your-git-server.com/server-side-fork.git contract-change-prYou have to add the dependencies needed by the autogenerated tests
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-contract-verifier</artifactId>
<scope>test</scope>
</dependency>In the configuration of the Maven plugin we passed the packageWithBaseClasses property
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
</configuration>
</plugin>|
Important
|
We’ve decided to use the "convention based" naming by setting the packageWithBaseClasses property.
That means that 2 last packages will be combined into a name of the base test class. In our case the contracts
were placed under src/test/resources/contract/fraud. Since we don’t have 2 packages starting from the contracts
folder we’re picking only one which is fraud. We’re adding the Base suffix and we’re capitalizing fraud.
That gives us the FraudBase test class name.
|
That’s because all the generated tests will extend that class. Over there you can set up your Spring Context or
whatever is necessary. In our case we’re using Rest Assured MVC to start the server side FraudDetectionController.
package com.example.fraud;
import org.junit.Before;
import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc;
public class FraudBase {
@Before
public void setup() {
RestAssuredMockMvc.standaloneSetup(new FraudDetectionController(),
new FraudStatsController(stubbedStatsProvider()));
}
private StatsProvider stubbedStatsProvider() {
return fraudType -> {
switch (fraudType) {
case DRUNKS:
return 100;
case ALL:
return 200;
}
return 0;
};
}
public void assertThatRejectionReasonIsNull(Object rejectionReason) {
assert rejectionReason == null;
}
}Now, if you run the ./mvnw clean install you would get sth like this:
Results :
Tests in error:
ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed...That’s because you have a new contract from which a test was generated and it failed since you haven’t implemented the feature. The autogenerated test would look like this:
@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");
}As you can see all the producer() parts of the Contract that were present in the value(consumer(…), producer(…)) blocks got injected into the test.
What’s important here to note is that on the producer side we also are doing TDD. We have expectations in form of a test. This test is shooting a request to our own application to an URL, headers and body defined in the contract. It also is expecting very precisely defined values in the response. In other words you have is your red part of red, green and refactor. Time to convert the red into the green.
write the missing implementation
Now since we now what is the expected input and expected output let’s write the missing implementation.
@RequestMapping(value = "/fraudcheck", method = PUT)
public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
if (amountGreaterThanThreshold(fraudCheck)) {
return new FraudCheckResult(FraudCheckStatus.FRAUD, AMOUNT_TOO_HIGH);
}
return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
}If we execute ./mvnw clean install again the tests will pass. Since the Spring Cloud Contract Verifier plugin adds the tests to the generated-test-sources you can actually run those tests from your IDE.
deploy your app
Once you’ve finished your work it’s time to deploy your change. First merge the branch
git checkout master
git merge --no-ff contract-change-pr
git push origin masterThen we assume that your CI would run sth like ./mvnw clean deploy which would publish both the application and the stub artifcats.
As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):
merge branch to master
git checkout master
git merge --no-ff contract-change-prwork online
Now you can disable the offline work for Spring Cloud Contract Stub Runner ad provide where the repository with your stubs is placed. At this moment the stubs of the server side will be automatically downloaded from Nexus / Artifactory.
You can switch off the value of the workOffline parameter in your annotation. Below you can see an
example of achieving the same by changing the properties.
stubrunner:
ids: 'com.example:http-server-dsl:+:stubs:8080'
repositoryRoot: http://repo.spring.io/libs-snapshotAnd that’s it!
The best way to add the dependencies is to just use the proper starter dependency.
For stub-runner use spring-cloud-starter-stub-runner and when you’re using a plugin just add
spring-cloud-starter-contract-verifier.
Below you can find some resources related to Spring Cloud Contract Verifier and Stub Runner. Note that some can be outdated since the Spring Cloud Contract Verifier project is under constant development.
You can check out the video from the Warsaw JUG about Spring Cloud Contract:
Here you can find some samples.
For the time being Spring Cloud Contract Verifier is a JVM based tool. So it could be your first pick when you’re already creating software for the JVM. This project has a lot of really interesting features but especially quite a few of them definitely make Spring Cloud Contract Verifier stand out on the "market" of Consumer Driven Contract (CDC) tooling. Out of many the most interesting are:
-
Possibility to do CDC with messaging
-
Clear and easy to use, statically typed DSL
-
Possibility to copy paste your current JSON file to the contract and only edit its elements
-
Automatic generation of tests from the defined Contract
-
Stub Runner functionality - the stubs are automatically downloaded at runtime from Nexus / Artifactory
-
Spring Cloud integration - no discovery service is needed for integration tests
One of the biggest challenges related to stubs is their reusability. Only if they can be vastly used, will they serve their purpose. What typically makes that difficult are the hard-coded values of request / response elements. For example dates or ids. Imagine the following JSON request
{
"time" : "2016-10-10 20:10:15",
"id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
"body" : "foo"
}and JSON response
{
"time" : "2016-10-10 21:10:15",
"id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
"body" : "bar"
}Imagine the pain required to set proper value of the time field (let’s assume that this content is generated by the
database) by changing the clock in the system or providing stub implementations of data providers. The same is related
to the field called id. Will you create a stubbed implementation of UUID generator? Makes little sense…
So as a consumer you would like to send a request that matches any form of a time or any UUID. That way your system
will work as usual - will generate data and you won’t have to stub anything out. Let’s assume that in case of the aforementioned
JSON the most important part is the body field. You can focus on that and provide matching for other fields. In other words
you would like the stub to work like this:
{
"time" : "SOMETHING THAT MATCHES TIME",
"id" : "SOMETHING THAT MATCHES UUID",
"body" : "foo"
}As far as the response goes as a consumer you need a concrete value that you can operate on. So such a JSON is valid
{
"time" : "2016-10-10 21:10:15",
"id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
"body" : "bar"
}As you could see in the previous sections we generate tests from contracts. So from the producer’s side the situation looks much different. We’re parsing the provided contract and in the test we want to send a real request to your endpoints. So for the case of a producer for the request we can’t have any sort of matching. We need concrete values that the producer’s backend can work on. Such a JSON would be a valid one:
{
"time" : "2016-10-10 20:10:15",
"id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
"body" : "foo"
}On the other hand from the point of view of the validity of the contract the response doesn’t necessarily have to
contain concrete values of time or id. Let’s say that you generate those on the producer side - again, you’d
have to do a lot of stubbing to ensure that you always return the same values. That’s why from the producer’s side
what you might want is the following response:
{
"time" : "SOMETHING THAT MATCHES TIME",
"id" : "SOMETHING THAT MATCHES UUID",
"body" : "bar"
}How can you then provide one time a matcher for the consumer and a concrete value for the producer and vice versa? In Spring Cloud Contract we’re allowing you to provide a dynamic value. That means that it can differ for both sides of the communication. You can pass the values:
Either via the value method
value(consumer(...), producer(...))
value(stub(...), test(...))
value(client(...), server(...))or using the $() method
$(consumer(...), producer(...))
$(stub(...), test(...))
$(client(...), server(...))You can read more about this in the Contract DSL section.
Calling value() or $() tells Spring Cloud Contract that you will be passing a dynamic value.
Inside the consumer() method you pass the value that should be used on the consumer side (in the generated stub).
Inside the producer() method you pass the value that should be used on the producer side (in the generated test).
|
Tip
|
If on one side you have passed the regular expression and you haven’t passed the other, then the other side will get auto-generated. |
Most often you will use that method together with the regex helper method. E.g. consumer(regex('[0-9]{10}')).
To sum it up the contract for the aforementioned scenario would look more or less like this (the regular expression for time and UUID are simplified and most likely invalid but we want to keep things very simple in this example):
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
url '/someUrl'
body([
time : value(consumer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
id: value(consumer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
body: "foo"
])
}
response {
status 200
body([
time : value(producer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
id: value([producer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
body: "bar"
])
}
}|
Important
|
Please read the Groovy docs related to JSON to understand how to properly structure the request / response bodies. |
Let’s try to answer a question what versioning really means. If you’re referring to the API version then there are different approaches.
-
use Hypermedia, links and do not version your API by any means
-
pass versions through headers / urls
I will not try to answer a question which approach is better. Whatever suit your needs and allows you to generate business value should be picked.
Let’s assume that you do version your API. In that case you should provide as many contracts as many versions you support. You can create a subfolder for every version or append it to th contract name - whatever suits you more.
If by versioning you mean the version of the JAR that contains the stubs then there are essentially two main approaches.
Let’s assume that you’re doing Continuous Delivery / Deployment which means that you’re generating a new version of the jar each time you go through the pipeline and that jar can go to production at any time. For example your jar version looks like this (it got built on the 20.10.2016 at 20:15:21) :
1.0.0.20161020-201521-RELEASEIn that case your generated stub jar will look like this.
1.0.0.20161020-201521-RELEASE-stubs.jarIn this case you should inside your application.yml or @AutoConfigureStubRunner when referencing stubs provide the
latest version of the stubs. You can do that by passing the + sign. Example
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})If the versioning however is fixed (e.g. 1.0.4.RELEASE or 2.1.1) then you have to set the concrete value of the jar
version. Example for 2.1.1.
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:2.1.1:stubs:8080"})You can manipulate the classifier to run the tests against current development version of the stubs of other services
or the ones that were deployed to production. If you alter your build to deploy the stubs with the prod-stubs classifier
once you reach production deployment then you can run tests in one case with dev stubs and one with prod stubs.
Example of tests using development version of stubs
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})Example of tests using production version of stubs
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:prod-stubs:8080"})You can pass those values also via properties from your deployment pipeline.
Another way of storing contracts other than having them with the producer is keeping them in a common place. It can be related to security issues where the consumers can’t clone the producer’s code. Also if you keep contracts in a single place then you, as a producer, will know how many consumers you have and which consumer will you break with your local changes.
Let’s assume that we have a producer with coordinates com.example:server and 3 consumers: client1,
client2, client3. Then in the repository with common contracts you would have the following setup
(which you can checkout here:
├── com
│ └── example
│ └── server
│ ├── client1
│ │ └── expectation.groovy
│ ├── client2
│ │ └── expectation.groovy
│ ├── client3
│ │ └── expectation.groovy
│ └── pom.xml
├── mvnw
├── mvnw.cmd
├── pom.xml
└── src
└── assembly
└── contracts.xmlAs you can see the under the slash-delimited groupid / artifact id folder (com/example/server) you have
expectations of the 3 consumers (client1, client2 and client3). Expectations are the standard Groovy DSL
contract files as described throughout this documentation. This repository has to produce a JAR file that maps
one to one to the contents of the repo.
Example of a pom.xml inside the server folder.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Server Stubs</name>
<description>POM used to install locally stubs for consumer side</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.4.BUILD-SNAPSHOT</version>
<relativePath />
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<spring-cloud-contract.version>1.1.2.BUILD-SNAPSHOT</spring-cloud-contract.version>
<spring-cloud-dependencies.version>Dalston.BUILD-SNAPSHOT</spring-cloud-dependencies.version>
<excludeBuildFolders>true</excludeBuildFolders>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<!-- By default it would search under src/test/resources/ -->
<contractsDirectory>${project.basedir}</contractsDirectory>
</configuration>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>As you can see there are no dependencies other than the Spring Cloud Contract Maven Plugin.
Those poms are necessary for the consumer side to run mvn clean install -DskipTests to locally install
stubs of the producer project.
The pom.xml in the root folder can look like this:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example.standalone</groupId>
<artifactId>contracts</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Contracts</name>
<description>Contains all the Spring Cloud Contracts, well, contracts. JAR used by the producers to generate tests and stubs</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<id>contracts</id>
<phase>prepare-package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<attach>true</attach>
<descriptor>${basedir}/src/assembly/contracts.xml</descriptor>
<!-- If you want an explicit classifier remove the following line -->
<appendAssemblyId>false</appendAssemblyId>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>It’s using the assembly plugin in order to build the JAR with all the contracts. Example of such setup is here:
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 http://maven.apache.org/xsd/assembly-1.1.3.xsd">
<id>project</id>
<formats>
<format>jar</format>
</formats>
<includeBaseDirectory>false</includeBaseDirectory>
<fileSets>
<fileSet>
<directory>${project.basedir}</directory>
<outputDirectory>/</outputDirectory>
<useDefaultExcludes>true</useDefaultExcludes>
<excludes>
<exclude>**/${project.build.directory}/**</exclude>
<exclude>mvnw</exclude>
<exclude>mvnw.cmd</exclude>
<exclude>.mvn/**</exclude>
<exclude>src/**</exclude>
</excludes>
</fileSet>
</fileSets>
</assembly>The workflow would look similar to the one presented in the Step by step guide to CDC. The only difference
is that the producer doesn’t own the contracts anymore. So the consumer and the producer have to work on
common contracts in a common repository.
When the consumer wants to work on the contracts offline, instead of cloning the producer code, the
consumer team clones the common repository, goes to the required producer’s folder (e.g. com/example/server)
and runs mvn clean install -DskipTests to install locally the stubs converted from the contracts.
|
Tip
|
You need to have Maven installed locally |
As a producer it’s enough to alter the Spring Cloud Contract Verifier to provide the URL and the dependency of the JAR containing the contracts:
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<configuration>
<contractsRepositoryUrl>http://link/to/your/nexus/or/artifactory/or/sth</contractsRepositoryUrl>
<contractDependency>
<groupId>com.example.standalone</groupId>
<artifactId>contracts</artifactId>
</contractDependency>
</configuration>
</plugin>With this setup the JAR with groupid com.example.standalone and artifactid contracts will be downloaded
from http://link/to/your/nexus/or/artifactory/or/sth. It will be then unpacked in a local temporary folder
and contracts present under the com/example/server will be picked as the ones used to generate the
tests and the stubs. Due to this convention the producer team will know which consumer teams will be broken
when some incompatible changes are done.
The rest of the flow looks the same.
Yes! Check out the Different base classes for contracts sections of either Gradle or Maven plugins.
The generated tests all boil down to RestAssured in some form or fashion which relies on Apache HttpClient. HttpClient has a facility called wire logging which logs the entire request and response to HttpClient. Spring Boot has a logging common application property for doing this sort of thing, just add this to your application properties
logging.level.org.apache.http.wire=DEBUGHere you can find interesting links related to Spring Cloud Contract Verifier:
Modules giving you the possibility to use WireMock with different servers by using the "ambient" server embedded in a Spring Boot application. Check out the samples for more details.
|
Important
|
The Spring Cloud Release Train BOM imports spring-cloud-contract-dependencies
which in turn has exclusions for the dependencies needed by WireMock. This might lead to a situation that
even if you’re not using Spring Cloud Contract then your dependencies will be influenced
anyways.
|
If you have a Spring Boot application that uses Tomcat as an embedded
server, for example (the default with spring-boot-starter-web), then
you can simply add spring-cloud-contract-wiremock to your classpath
and add @AutoConfigureWireMock in order to be able to use Wiremock
in your tests. Wiremock runs as a stub server and you can register
stub behaviour using a Java API or via static JSON declarations as
part of your test. Here’s a simple example:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureWireMock(port = 0)
public class WiremockForDocsTests {
// A service that calls out over HTTP
@Autowired private Service service;
// Using the WireMock APIs in the normal way:
@Test
public void contextLoads() throws Exception {
// Stubbing WireMock
stubFor(get(urlEqualTo("/resource"))
.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World!");
}
}To start the stub server on a different port use @AutoConfigureWireMock(port=9999) (for example), and for a random port use the value 0. The stub server port will be bindable in the test application context as "wiremock.server.port". Using @AutoConfigureWireMock adds a bean of type WiremockConfiguration to your test application context, where it will be cached in between methods and classes having the same context, just like for normal Spring integration tests.
If you use @AutoConfigureWireMock then it will register WireMock
JSON stubs from the file system or classpath, by default from
file:src/test/resources/mappings. You can customize the locations
using the stubs attribute in the annotation, which can be a resource
pattern (ant-style) or a directory, in which case */.json is
appended. Example:
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureWireMock(stubs="classpath:/stubs")
public class WiremockImportApplicationTests {
@Autowired
private Service service;
@Test
public void contextLoads() throws Exception {
assertThat(this.service.go()).isEqualTo("Hello World!");
}
}
|
Note
|
Actually WireMock always loads mappings from
src/test/resources/mappings as well as the custom locations in the
stubs attribute. To change this behaviour you have to also specify a
files root as described next.
|
WireMock can read response bodies from files on the classpath or file
system. In that case you will see in the JSON DSL that the response
has a "bodyFileName" instead of a (literal) "body". The files are
resolved relative to a root directory src/test/resources/__files by
default. To customize this location you can set the files attribute
in the @AutoConfigureWireMock annotation to the location of the
parent directory (i.e. the place __files is a
subdirectory). You can use Spring resource notation to refer to
file:… or classpath:… locations (but generic URLs are not
supported). A list of values can be given and WireMock will resolve
the first file that exists when it needs to find a response body.
|
Note
|
when you configure the files root, then it affects the
automatic loading of stubs as well (they come from the root location
in a subdirectory called "mappings"). The value of files has no
effect on the stubs loaded explicitly from the stubs attribute.
|
For a more conventional WireMock experience, using JUnit @Rules to
start and stop the server, just use the WireMockSpring convenience
class to obtain an Options instance:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class WiremockForDocsClassRuleTests {
// Start WireMock on some dynamic port
// for some reason `dynamicPort()` is not working properly
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(
WireMockSpring.options().dynamicPort());
// A service that calls out over HTTP to localhost:${wiremock.port}
@Autowired
private Service service;
// Using the WireMock APIs in the normal way:
@Test
public void contextLoads() throws Exception {
// Stubbing WireMock
wiremock.stubFor(get(urlEqualTo("/resource"))
.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World!");
}
}The use @ClassRule means that the server will shut down after all the methods in this class.
WireMock allows you to stub a "secure" server with an "https" URL protocol. If your application wants to contact that stub server in an integration test, then it will find that the SSL certificates are not valid (it’s the usual problem with self-installed certificates). The best option is often to just re-configure the client to use "http", but if that’s not open to you then you can ask Spring to configure an HTTP client that ignores SSL validation errors (just for tests).
To make this work with minimum fuss you need to be using the Spring Boot RestTemplateBuilder in your app,
e.g.
@Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
return builder.build();
}This is because the builder is passed through callbacks to initalize it, so the SSL validation can be set up
in the client at that point. This will happen automatically in your test if you are using the
@AutoConfigureWireMock annotation (or the stub runner). If you are using the JUnit @Rule approach you need
to add the @AutoConfigureHttpClient annotation as well:
@RunWith(SpringRunner.class)
@SpringBootTest("app.baseUrl=https://localhost:6443")
@AutoConfigureHttpClient
public class WiremockHttpsServerApplicationTests {
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(
WireMockSpring.options().httpsPort(6443));
...
}If you are using spring-boot-starter-test then you will have the Apache HTTP client on the classpath and it will
be selected by the RestTemplateBuilder and configured to ignore SSL errors. If you are using the default java.net
client you don’t need the annotation (but it won’t do any harm). There is no support currently for other clients, but
it may be added in future releases.
Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into a
Spring MockRestServiceServer. Here’s an example:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.NONE)
public class WiremockForDocsMockServerApplicationTests {
@Autowired
private RestTemplate restTemplate;
@Autowired
private Service service;
@Test
public void contextLoads() throws Exception {
// will read stubs classpath
MockRestServiceServer server = WireMockRestServiceServer.with(this.restTemplate)
.baseUrl("http://example.org").stubs("classpath:/stubs/resource.json")
.build();
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World");
server.verify();
}
}The baseUrl is prepended to all mock calls, and the stubs()
method takes a stub path resource pattern as an argument. So in this
example the stub defined at /stubs/resource.json is loaded into the
mock server, so if the RestTemplate is asked to visit
http://example.org/ it will get the responses as declared
there. More than one stub pattern can be specified, and each one can
be a directory (for a recursive list of all ".json"), or a fixed
filename (like in the example above) or an ant-style pattern. The JSON
format is the normal WireMock format which you can read about in the
WireMock website.
Currently we support Tomcat, Jetty and Undertow as Spring Boot embedded servers, and Wiremock itself has "native" support for a particular version of Jetty (currently 9.2). To use the native Jetty you need to add the native wiremock dependencies and exclude the Spring Boot container if there is one.
Spring RestDocs can be
used to generate documentation (e.g. in asciidoctor format) for an
HTTP API with Spring MockMvc or Rest Assured. At the same time as you
generate documentation for your API, you can also generate WireMock
stubs, by using Spring Cloud Contract WireMock. Just write your normal
RestDocs test cases and use @AutoConfigureRestDocs to have stubs
automatically in the restdocs output directory. For example:
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureRestDocs(outputDir = "target/snippets")
@AutoConfigureMockMvc
public class ApplicationTests {
@Autowired
private MockMvc mockMvc;
@Test
public void contextLoads() throws Exception {
mockMvc.perform(get("/resource"))
.andExpect(content().string("Hello World"))
.andDo(document("resource"));
}
}From this test will be generated a WireMock stub at "target/snippets/stubs/resource.json". It matches all GET requests to the "/resource" path.
Without any additional configuration this will create a stub with a request matcher for the HTTP method and all headers except "host" and "content-length". To match the request more precisely, for example to match the body of a POST or PUT, we need to explicitly create a request matcher. This will do two things: 1) create a stub that only matches the way you specify, 2) assert that the request in the test case also matches the same conditions.
The main entry point for this is WireMockRestDocs.verify() which can
be used as a substitute for the document() convenience method. For
example:
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureRestDocs(outputDir = "target/snippets")
@AutoConfigureMockMvc
public class ApplicationTests {
@Autowired
private MockMvc mockMvc;
@Test
public void contextLoads() throws Exception {
mockMvc.perform(post("/resource")
.content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
.andExpect(status().isOk())
.andDo(verify().jsonPath("$.id")
.stub("resource"));
}
}So this contract is saying: any valid POST with an "id" field will get
back an the same response as in this test. You can chain together
calls to .jsonPath() to add additional matchers. The
JayWay documentation can help you
to get up to speed with JSON Path if it is unfamiliar to you.
Instead of the jsonPath and contentType convenience methods, you
can also use the WireMock APIs to verify the request matches the
created stub. Example:
@Test
public void contextLoads() throws Exception {
mockMvc.perform(post("/resource")
.content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
.andExpect(status().isOk())
.andDo(verify()
.wiremock(WireMock.post(
urlPathEquals("/resource"))
.withRequestBody(matchingJsonPath("$.id"))
.stub("post-resource"));
}The WireMock API is rich - you can match headers, query parameters, and request body by regex as well as by json path - so this can useful to create stubs with a wider range of parameters. The above example will generate a stub something like this:
{
"request" : {
"url" : "/resource",
"method" : "POST",
"bodyPatterns" : [ {
"matchesJsonPath" : "$.id"
}]
},
"response" : {
"status" : 200,
"body" : "Hello World",
"headers" : {
"X-Application-Context" : "application:-1",
"Content-Type" : "text/plain"
}
}
}|
Note
|
You can use either the wiremock() method or the jsonPath()
and contentType() methods to create request matchers, but not both.
|
On the consumer side, you can make the resource.json generated above
available on the classpath (by publishing stubs as JARs for example).
After that, you can create a stub using WireMock in a
number of different ways, including as described above using
@AutoConfigureWireMock(stubs="classpath:resource.json").
Another thing that can be generated with Spring RestDocs is the Spring Cloud Contract DSL file and documentation. If you combine that with Spring Cloud WireMock then you’re getting both the contracts and stubs.
Why would you want to use this feature? Some people in the community asked questions about situation in which they would like to move to DSL based contract definition but they already have a lot of Spring MVC tests. Using this feature allows you to generate the contract files that you can later modify and move to proper folders so that the plugin picks them up.
|
Tip
|
You might wonder why this functionality is in the WireMock module. Come to think of it, it does make sense since it makes little sense to generate only contracts and not generate the stubs. That’s why we suggest to do both. |
Let’s imagine the following test:
this.mockMvc.perform(post("/foo")
.accept(MediaType.APPLICATION_PDF)
.accept(MediaType.APPLICATION_JSON)
.contentType(MediaType.APPLICATION_JSON)
.content("{\"foo\": 23 }"))
.andExpect(status().isOk())
.andExpect(content().string("bar"))
// first WireMock
.andDo(WireMockRestDocs.verify()
.jsonPath("$[?(@.foo >= 20)]")
.contentType(MediaType.valueOf("application/json"))
.stub("shouldGrantABeerIfOldEnough"))
// then Contract DSL documentation
.andDo(document("index", SpringCloudContractRestDocs.dslContract()));This will lead in the creation of the stub as presented in the previous section, contract will get generated and a documentation file too.
The contract will be called index.groovy and look more like this.
import org.springframework.cloud.contract.spec.Contract
Contract.make {
request {
method 'POST'
url '/foo'
body('''
{"foo": 23 }
''')
headers {
header('''Accept''', '''application/json''')
header('''Content-Type''', '''application/json''')
}
}
response {
status 200
body('''
bar
''')
headers {
header('''Content-Type''', '''application/json;charset=UTF-8''')
header('''Content-Length''', '''3''')
}
testMatchers {
jsonPath('$[?(@.foo >= 20)]', byType())
}
}
}the generated document (example for Asciidoc) will contain a formatted contract
(the location of this file would be index/dsl-contract.adoc).
You can read more about Spring Cloud Contract Verifier by reading the {documentation_url}[docs]
Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.
Before we accept a non-trivial patch or pull request we will need you to sign the Contributor License Agreement. Signing the contributor’s agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. Active contributors might be asked to join the core team, and given the ability to merge pull requests.
This project adheres to the Contributor Covenant code of conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to spring-code-of-conduct@pivotal.io.
None of these is essential for a pull request, but they will all help. They can also be added after the original pull request but before a merge.
-
Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the
eclipse-code-formatter.xmlfile from the Spring Cloud Build project. If using IntelliJ, you can use the Eclipse Code Formatter Plugin to import the same file. -
Make sure all new
.javafiles to have a simple Javadoc class comment with at least an@authortag identifying you, and preferably at least a paragraph on what the class is for. -
Add the ASF license header comment to all new
.javafiles (copy from existing files in the project) -
Add yourself as an
@authorto the .java files that you modify substantially (more than cosmetic changes). -
Add some Javadocs and, if you change the namespace, some XSD doc elements.
-
A few unit tests would help a lot as well — someone has to do it.
-
If no-one else is using your branch, please rebase it against the current master (or other target branch in the main project).
-
When writing a commit message please follow these conventions, if you are fixing an existing issue please add
Fixes gh-XXXXat the end of the commit message (where XXXX is the issue number).
|
Important
|
You need to have all the necessary Groovy plugins installed for your IDE to properly resolve the sources. For example in Intellij IDEA having both Eclipse Groovy Compiler Plugin & GMavenPlus Intellij Plugin results in properly imported project. |
Here you can find the Spring Cloud Contract folder structure
├── samples
├── scripts
├── spring-cloud-contract-dependencies
├── spring-cloud-contract-spec
├── spring-cloud-contract-starters
├── spring-cloud-contract-stub-runner
├── spring-cloud-contract-tools
├── spring-cloud-contract-verifier
├── spring-cloud-contract-wiremock
└── tests-
samples- folder contains test samples together with standalone ones used also to build documentation -
scripts- contains scripts to build and testSpring Cloud Contractwith Maven, Gradle and standalone projects -
spring-cloud-contract-dependencies- contains Spring Cloud Contract BOM -
spring-cloud-contract-starters- contains Spring Cloud Contract Starters -
spring-cloud-contract-spec- contains specification modules (contains concept of a Contract) -
spring-cloud-contract-stub-runner- contains Stub Runner related modules -
spring-cloud-contract-tools- Gradle and Maven plugin forSpring Cloud Contract Verifier -
spring-cloud-contract-verifier- core of theSpring Cloud Contract Verifierfunctionality -
spring-cloud-contract-wiremock- all WireMock related functionality -
tests- integration tests for different messaging technologies
To build the core functionality together with Maven Plugin you can run
./mvnw clean install -P integrationCalling that function will build core, Maven plugin, Gradle plugin and run end to end tests on the standalone samples in proper order (both for Maven and Gradle).
To build the Gradle Plugin only
cd spring-cloud-contract-tools/spring-cloud-contract-gradle-plugin
./gradlew clean buildWe’re providing a couple of helpful scripts to build the project.
To build the project in parallel (by default uses 4 cores but you can change it)
./scripts/parallelBuild.shand with 8 cores
CORES=8 ./scripts/parallelBuild.shTo build the project without any integration tests (by default uses 1 core)
./scripts/noIntegration.shand with 8 cores
CORES=8 ./scripts/noIntegration.shTo generate the documentation (both the root one and the maven plugin one)
./scripts/generateDocs.sh