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:introduction_url: ../../../..

== Spring Cloud Contract

You always need confidence when pushing new features into a new application or service in
a distributed system. To that end, 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, and asserting that a contract is kept by
producers and consumers -- for both HTTP and message-based interactions.

=== Spring Cloud Contract workshops

If you prefer to learn about the project by doing some tutorials, you can check out the
workshops under
https://cloud-samples.spring.io/spring-cloud-contract-samples/workshops.html[this link].

=== Spring Cloud Contract Verifier

== Spring Cloud Contract Verifier Introduction

TIP: The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski
(https://github.com/Codearte[Codearte])

Spring Cloud Contract Verifier enables Consumer Driven Contract (CDC) development of
JVM-based applications. It moves TDD to the level of software architecture.

Spring Cloud Contract Verifier ships with _Contract Definition Language_ (CDL). Contract
definitions are used to produce the 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, and test data is
produced by Spring Cloud Contract Verifier.
* Messaging routes, if you're using a messaging service. We integrate with Spring
Integration, Spring Cloud Stream, Spring AMQP, and Apache Camel. You can also set your
own integrations.
* Acceptance tests (in JUnit or Spock) are used to verify if server-side implementation
of the API is compliant with the contract (__server tests__). A full test is generated by
Spring Cloud Contract Verifier.

=== Why a Contract Verifier?

Assume that we have a system consisting of multiple microservices:

image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-contract/{branch}/docs/src/main/asciidoc/images/Deps.png[Microservices Architecture]

==== Testing issues

If we wanted to test the application in top left corner to determine whether it can
communicate with other services, 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.

*Deploy all microservices and perform end to end tests*

Advantages:

- Simulates production.
- Tests real communication between services.

Disadvantages:

- To test one microservice, we have to deploy 6 microservices, a couple of databases,
etc.
- The environment where the tests run is locked for a single suite of tests (nobody else
would be able to run the tests in the meantime).
- They take a long time to run.
- The feedback comes very late in the process.
- They are extremely hard to debug.

*Mock other microservices in unit/integration tests*

Advantages:

- They provide very fast feedback.
- They have no infrastructure requirements.

Disadvantages:

- The implementor of the service creates stubs that might have nothing to do with
reality.
- You can go to production with passing tests and failing production.

To solve the aforementioned issues, Spring Cloud Contract Verifier with Stub Runner was
created. The 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 directly uses.

image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-contract/{branch}/docs/src/main/asciidoc/images/Stubs2.png[Stubbed Services]

Spring Cloud Contract Verifier gives you the certainty that the stubs that you use 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 short, you can trust those stubs.

=== Purposes

The main purposes of Spring Cloud Contract Verifier with Stub Runner are:

- To ensure that WireMock/Messaging stubs (used when developing the client) do exactly
what the actual server-side implementation does.
- 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 to be used on the server side.

IMPORTANT: Spring Cloud Contract Verifier's purpose is NOT to start writing business
features in the contracts. 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 case and one for the negative case. Contract tests are
used to test contracts between applications and not to simulate full behavior.

=== How It Works

This section explores how Spring Cloud Contract Verifier with Stub Runner works.

==== Defining the contract

As consumers of services, we need to define what exactly we want to achieve. We need to
formulate our expectations. That is why we write contracts.

Assume that you want to send a request containing the ID of a client company and the
amount it wants to borrow from us. You also want to send it to the /fraudcheck url via
the PUT method.

.Groovy DSL
[source,groovy,indent=0]
----
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 `client.id` 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 `client.id` 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.*`
 */
----

.YAML
[source,yml,indent=0]
----
request: # (1)
  method: PUT # (2)
  url: /fraudcheck # (3)
  body: # (4)
    "client.id": 1234567890
    loanAmount: 99999
  headers: # (5)
    Content-Type: application/json
  matchers:
    body:
      - path: $.['client.id'] # (6)
        type: by_regex
        value: "[0-9]{10}"
response: # (7)
  status: 200 # (8)
  body:  # (9)
    fraudCheckStatus: "FRAUD"
    "rejection.reason": "Amount too high"
  headers: # (10)
    Content-Type: application/json;charset=UTF-8


#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 `client.id`
# * has a field `loanAmount` that is equal to `99999`
#(5) - with header `Content-Type` equal to `application/json`
#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
#(7) - then the response will be sent with
#(8) - status equal `200`
#(9) - and JSON body equal to
# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
#(10) - 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 `client.id` `1234567890`
# * has a field `loanAmount` that is equal to `99999`
#(5) - with header `Content-Type` equal to `application/json`
#(7) - then the test will assert if the response has been sent with
#(8) - status equal `200`
#(9) - and JSON body equal to
# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`
----

==== Client Side

Spring Cloud Contract generates stubs, which you can use during client-side testing.
You get a running WireMock instance/Messaging route that simulates the service.
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.

[source,groovy,indent=0]
----
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.

[source,groovy,indent=0]
----
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
public class LoanApplicationServiceTests {
----

After that, during the tests, Spring Cloud Contract automatically finds the stubs
(simulating the real service) in the Maven repository and exposes them on a configured
(or random) port.

==== Server Side

Since you are developing your stub, you need to be sure that it actually resembles your
concrete implementation. You cannot have a situation where your stub acts in one way and
your application behaves in a different way, especially in production.

To ensure that your application behaves the way you define in your stub, tests are
generated from the stub you provide.

The autogenerated test looks, more or less, like this:

[source,java,indent=0]
----
@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");
}
----

=== Step-by-step Guide to Consumer Driven Contracts (CDC)

Consider an example of Fraud Detection and the Loan Issuance process. The business
scenario is such that we want to issue loans to people but do not want them to steal from
us. The current implementation of our system grants loans to everybody.

Assume that `Loan Issuance` is a client to the `Fraud Detection` server. In the current
sprint, we must develop a new feature: if a client wants to borrow too much money, then
we mark the client as a fraud.

Technical remark - Fraud Detection has an `artifact-id` of `http-server`, while Loan
Issuance has an artifact-id of `http-client`, and both have a `group-id` of `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.

The https://github.com/spring-cloud/spring-cloud-contract/tree/{branch}/samples/standalone/dsl/http-server[server
side code is available here] and https://github.com/spring-cloud/spring-cloud-contract/tree/{branch}/samples/standalone/dsl/http-client[the
client code here].

TIP: In this case, the producer owns the contracts. Physically, all the contract are
in the producer's repository.

==== Technical note

If using the *SNAPSHOT* / *Milestone* / *Release Candidate* versions please add the
following section to your build:

[source,xml,indent=0,subs="verbatim,attributes",role="primary"]
.Maven
----
<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>
----

[source,groovy,indent=0,subs="verbatim,attributes",role="secondary"]
.Gradle
----
repositories {
	mavenCentral()
	mavenLocal()
	maven { url "https://repo.spring.io/snapshot" }
	maven { url "https://repo.spring.io/milestone" }
	maven { url "https://repo.spring.io/release" }
}
----

==== Consumer side (Loan Issuance)

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server), you might do the following steps:

. Start doing TDD by writing a test for your feature.
. Write the missing implementation.
. Clone the Fraud Detection service repository locally.
. Define the contract locally in the repo of Fraud Detection service.
. Add the Spring Cloud Contract Verifier plugin.
. Run the integration tests.
. File a pull request.
. Create an initial implementation.
. Take over the pull request.
. Write the missing implementation.
. Deploy your app.
. Work online.

*Start doing TDD by writing a test for your feature.*

[source,groovy,indent=0]
----
@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");
}
----

Assume that you have written a test of your new feature. If a loan application for a big
amount is received, the system 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. Assume
that you need to send the request containing the ID of the client and the amount the
client wants to borrow. You want to send it to the `/fraudcheck` url via the `PUT` method.

[source,groovy,indent=0]
----
ResponseEntity<FraudServiceResponse> response =
        restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
                new HttpEntity<>(request, httpHeaders),
                FraudServiceResponse.class);
----

For simplicity, the port of the Fraud Detection service is set to `8080`, and the
application runs on `8090`.

If you start the test at this point, it breaks, because no service currently runs on port
`8080`.

*Clone the Fraud Detection service repository locally.*

You can start by playing around with the server side contract. To do so, you must first
clone it.

[source,bash,indent=0]
----
$ git clone https://your-git-server.com/server-side.git local-http-server-repo
----

*Define the contract locally in the repo of Fraud Detection service.*

As a consumer, you need to define what exactly you want to achieve. You need to formulate
your expectations. To do so, write the following contract:

IMPORTANT: Place the contract under `src/test/resources/contracts/fraud` folder. The `fraud` folder
is important because the producer's test base class name references that folder.

.Groovy DSL
[source,groovy,indent=0]
----
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 `client.id` 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 `client.id` 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.*`
 */
----

.YAML
[source,yml,indent=0]
----
request: # (1)
  method: PUT # (2)
  url: /fraudcheck # (3)
  body: # (4)
    "client.id": 1234567890
    loanAmount: 99999
  headers: # (5)
    Content-Type: application/json
  matchers:
    body:
      - path: $.['client.id'] # (6)
        type: by_regex
        value: "[0-9]{10}"
response: # (7)
  status: 200 # (8)
  body:  # (9)
    fraudCheckStatus: "FRAUD"
    "rejection.reason": "Amount too high"
  headers: # (10)
    Content-Type: application/json;charset=UTF-8


#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 `client.id`
# * has a field `loanAmount` that is equal to `99999`
#(5) - with header `Content-Type` equal to `application/json`
#(6) - and a `client.id` json entry matches the regular expression `[0-9]{10}`
#(7) - then the response will be sent with
#(8) - status equal `200`
#(9) - and JSON body equal to
# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
#(10) - 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 `client.id` `1234567890`
# * has a field `loanAmount` that is equal to `99999`
#(5) - with header `Content-Type` equal to `application/json`
#(7) - then the test will assert if the response has been sent with
#(8) - status equal `200`
#(9) - and JSON body equal to
# { "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
#(10) - with header `Content-Type` equal to `application/json;charset=UTF-8`
----

The YML contract is quite straight-forward. However when you take a look at the Contract
written using a statically typed Groovy DSL - you might wonder what the
`value(client(...), server(...))` parts are. By using this notation, Spring Cloud
Contract lets you define parts of a JSON block, a URL, etc., which are dynamic. In case
of an identifier or a timestamp, you need not hardcode a value. You want to allow some
different ranges of values. To enable ranges of values, you can set regular expressions
matching those values for the consumer side. You can provide the body by means of either
a map notation or String with interpolations.
https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html#_contract_dsl[Consult the docs
for more information.] We highly recommend using the map notation!

TIP: You must understand the map notation in order to set up contracts. Please read the
https://groovy-lang.org/json.html[Groovy docs regarding JSON].

The previously shown contract is an agreement between two sides that:

- if an HTTP request is sent with all of
** a `PUT` method on the `/fraudcheck` endpoint,
** a JSON body with a `client.id` that matches the regular expression `[0-9]{10}` and
`loanAmount` equal to `99999`,
** and a `Content-Type` header with a value of `application/vnd.fraud.v1+json`,
- then an HTTP response is sent to the consumer that
** has status `200`,
** contains a JSON body with the `fraudCheckStatus` field containing a value `FRAUD` and
the `rejectionReason` field having value `Amount too high`,
** and a `Content-Type` header with a value of `application/vnd.fraud.v1+json`.

Once you are ready to check the API in practice in the integration tests, you need to
install the stubs locally.

*Add the Spring Cloud Contract Verifier plugin.*

We can add either a Maven or a Gradle plugin. In this example, you see how to add Maven.
First, add the `Spring Cloud Contract` BOM.

[source,xml,indent=0]
----
<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, add the `Spring Cloud Contract Verifier` Maven plugin

[source,xml,indent=0]
----
<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, you get the `Spring Cloud Contract Verifier` features which,
from the provided contracts:

- generate and run tests
- produce and install stubs

You do not want to generate tests since you, as the consumer, want only to play with the
stubs. You need to skip the test generation and execution. When you execute:

[source,bash,indent=0]
----
$ cd local-http-server-repo
$ ./mvnw clean install -DskipTests
----

In the logs, you see something like this:

[source,bash,indent=0]
----
[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:1.5.5.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.jar
----

The following line is extremely important:

[source,bash,indent=0]
----
[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.jar
----

It confirms 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 must do the following in your consumer side project (`Loan
Application service`):

Add the `Spring Cloud Contract` BOM:

[source,xml,indent=0]
----
<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`:

[source,xml,indent=0]
----
<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 the stubs of your
collaborators. (Optional step) Because you're playing with the collaborators offline, you
can also provide the offline work switch.

[source,groovy,indent=0]
----
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
public class LoanApplicationServiceTests {
----

Now, when you run your tests, you see something like this:

[source,bash,indent=0]
----
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}]
----

This output means that Stub Runner has found your stubs and started a server for your 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 pull request.*

What you have done until now is an iterative process. You can play around with the
contract, install it locally, and work on the consumer side until the contract works as
you wish.

Once you are satisfied with the results and the test passes, publish a pull request to
the server side. Currently, the consumer side work is done.

==== Producer side (Fraud Detection server)

As a developer of the Fraud Detection server (a server to the Loan Issuance service):

*Create an initial implementation.*

As a reminder, you can see the initial implementation here:

[source,java,indent=0]
----
@RequestMapping(value = "/fraudcheck", method = PUT)
public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
}
----

*Take over the pull request.*

[source,bash,indent=0]
----
$ git checkout -b contract-change-pr master
$ git pull https://your-git-server.com/server-side-fork.git contract-change-pr
----

You must add the dependencies needed by the autogenerated tests:

[source,xml,indent=0]
----
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-contract-verifier</artifactId>
    <scope>test</scope>
</dependency>
----

In the configuration of the Maven plugin, pass the `packageWithBaseClasses` property

[source,xml,indent=0]
----
<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: This example uses "convention based" naming by setting the
`packageWithBaseClasses` property. Doing so means that the two last packages combine to
make the name of the base test class. In our case, the contracts were placed under
`src/test/resources/contracts/fraud`. Since you do not have two packages starting from
the `contracts` folder, pick only one, which should be `fraud`. Add the `Base` suffix and
capitalize `fraud`. That gives you the `FraudBase` test class name.

All the generated tests extend that class. Over there, you can set up your Spring Context
or whatever is necessary. In this case, use https://github.com/rest-assured/rest-assured[Rest Assured MVC] to
start the server side `FraudDetectionController`.

[source,java,indent=0]
----
package com.example.fraud;

import org.junit.Before;

import io.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 get something like this:

[source,bash,indent=0]
----
Results :

Tests in error:
  ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed...
----

This error occurs because you have a new contract from which a test was generated and it
failed since you have not implemented the feature. The auto-generated test would look
like this:

[source,java,indent=0]
----
@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");
}
----

If you used the Groovy DSL, you can see, all the `producer()` parts of the Contract that were present in the
`value(consumer(...), producer(...))` blocks got injected into the test.
In case of using YAML, the same applied for the `matchers` sections of the `response`.

Note that, on the producer side, you are also doing TDD. The expectations are expressed
in the form of a test. This test sends a request to our own application with the URL,
headers, and body defined in the contract. It also is expecting precisely defined values
in the response. In other words, you have the `red` part of `red`, `green`, and
`refactor`. It is time to convert the `red` into the `green`.

*Write the missing implementation.*

Because you know the expected input and expected output, you can write the missing
implementation:

[source,java,indent=0]
----
@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);
}
----

When you execute `./mvnw clean install` again, the tests 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 finish your work, you can deploy your change. First, merge the branch:

[source,bash,indent=0]
----
$ git checkout master
$ git merge --no-ff contract-change-pr
$ git push origin master
----

Your CI might run something like `./mvnw clean deploy`, which would publish both the
application and the stub artifacts.

==== Consumer Side (Loan Issuance) Final Step

As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):

*Merge branch to master.*

[source,bash,indent=0]
----
$ git checkout master
$ git merge --no-ff contract-change-pr
----

*Work online.*

Now you can disable the offline work for Spring Cloud Contract Stub Runner and indicate
where the repository with your stubs is located. At this moment the stubs of the server
side are automatically downloaded from Nexus/Artifactory. You can switch off the value of
the `workOffline` parameter in your annotation. The following code shows an example of
achieving the same thing by changing the properties.

[source,yaml,indent=0]
----
stubrunner:
  ids: 'com.example:http-server-dsl:+:stubs:8080'
  repositoryRoot: https://repo.spring.io/libs-snapshot
----

That's it!

=== Dependencies

The best way to add dependencies is to use the proper `starter` dependency.

For `stub-runner`, use `spring-cloud-starter-stub-runner`. When you use a plugin, add
`spring-cloud-starter-contract-verifier`.

=== Additional Links

Here are some resources related to Spring Cloud Contract Verifier and Stub Runner. Note
that some may be outdated, because the Spring Cloud Contract Verifier project is under
constant development.

==== Spring Cloud Contract video

You can check out the video from the Warsaw JUG about Spring Cloud Contract:

video::sAAklvxmPmk[youtube,start=538,width=640,height=480]

==== Readings

- https://www.slideshare.net/MarcinGrzejszczak/stick-to-the-rules-consumer-driven-contracts-201507-confitura[Slides from Marcin Grzejszczak's talk about Accurest]
- https://toomuchcoding.com/blog/categories/accurest/[Accurest related articles from Marcin Grzejszczak's blog]
- https://toomuchcoding.com/blog/categories/spring-cloud-contract/[Spring Cloud Contract related articles from Marcin Grzejszczak's blog]
- https://groovy-lang.org/json.html[Groovy docs regarding JSON]

=== Samples

You can find some samples at
https://github.com/spring-cloud-samples/spring-cloud-contract-samples[samples].

== Links

The following links may be helpful when working with Spring Cloud Contract Verifier:

* https://github.com/spring-cloud/spring-cloud-contract/[Spring Cloud Contract Github
Repository]
* https://github.com/spring-cloud-samples/spring-cloud-contract-samples/[Spring Cloud
Contract Samples]
* https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html[Spring Cloud
Contract Documentation]
* https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html/deprecated[Accurest
Legacy Documentation]
* https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html/#spring-cloud-contract-stub-runner[Spring
Cloud Contract Stub Runner Documentation]
* https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html/#stub-runner-for-messaging[Spring
Cloud Contract Stub Runner Messaging Documentation]
* https://gitter.im/spring-cloud/spring-cloud-contract[Spring Cloud Contract Gitter]
* https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract-maven-plugin/[Spring
Cloud Contract Maven Plugin]
* https://www.youtube.com/watch?v=sAAklvxmPmk[Spring Cloud Contract WJUG Presentation by
Marcin Grzejszczak]

=== Spring Cloud Contract WireMock

:core_path: ../../../..
:doc_samples: {core_path}/samples/wiremock-jetty
:wiremock_tests: {core_path}/spring-cloud-contract-wiremock

== Spring Cloud Contract WireMock

The Spring Cloud Contract WireMock modules let you use https://github.com/tomakehurst/wiremock[WireMock] in a
Spring Boot application. Check out the
https://github.com/spring-cloud/spring-cloud-contract/tree/{branch}/samples[samples]
for more details.

If you have a Spring Boot application that uses Tomcat as an embedded server (which is
the default with `spring-boot-starter-web`),  you can add
`spring-cloud-starter-contract-stub-runner` 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 behavior using a Java API or via static JSON declarations as part of
your test. The following code shows an example:

[source,java,indent=0]
----
@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 (for example),
`@AutoConfigureWireMock(port=9999)`. For a random port, use a value of `0`. The stub
server port can be bound in the test application context with the "wiremock.server.port"
property. 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, the same as for Spring integration tests.

=== Registering Stubs Automatically

If you use `@AutoConfigureWireMock`, it registers 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 an
Ant-style resource pattern or a directory. In the case of a directory, `**/*.json` is
appended. The following code shows an 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 behavior, you can
also specify a files root as described in the next section of this document.

=== Using Files to Specify the Stub Bodies

WireMock can read response bodies from files on the classpath or the file system. In that
case, you can 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 (by default,
`src/test/resources/\__files`). To customize this location you can set the `files`
attribute in the `@AutoConfigureWireMock` annotation to the location of the parent
directory (in other words, `__files` is a subdirectory). You can use Spring resource
notation to refer to `file:...` or `classpath:...` locations. Generic URLs are not
supported. A list of values can be given, in which case WireMock resolves the first file
that exists when it needs to find a response body.

NOTE: When you configure the `files` root, it also affects the
automatic loading of stubs, because 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.

=== Alternative: Using JUnit Rules

For a more conventional WireMock experience, you can use JUnit `@Rules` to start and stop
the server. To do so, use the `WireMockSpring` convenience class to obtain an `Options`
instance, as shown in the following example:

[source,java,indent=0]
----
@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 `@ClassRule` means that the server shuts down after all the methods in this class
have been run.

=== Relaxed SSL Validation for Rest Template

WireMock lets you stub a "secure" server with an "https" URL protocol. If your
application wants to contact that stub server in an integration test, it will find that
the SSL certificates are not valid (the usual problem with self-installed certificates).
The best option is often to re-configure the client to use "http". If that's not an
option, you can ask Spring to configure an HTTP client that ignores SSL validation errors
(do so only for tests, of course).

To make this work with minimum fuss, you need to be using the Spring Boot
`RestTemplateBuilder` in your app, as shown in the following example:

[source,java,indent=0]
----
	@Bean
	public RestTemplate restTemplate(RestTemplateBuilder builder) {
		return builder.build();
	}
----

You need `RestTemplateBuilder` because the builder is passed through callbacks to
initialize it, so the SSL validation can be set up in the client at that point. This
happens automatically in your test if you are using the `@AutoConfigureWireMock`
annotation or the stub runner. If you use the JUnit `@Rule` approach, you need to add the
`@AutoConfigureHttpClient` annotation as well, as shown in the following example:

[source,java,indent=0]
----
@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`, you have the Apache HTTP client on the
classpath and it is selected by the `RestTemplateBuilder` and configured to ignore SSL
errors. If you use the default `java.net` client, you do not 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.

=== WireMock and Spring MVC Mocks

Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into
a Spring `MockRestServiceServer`. The following code shows an example:

[source,java,indent=0]
----
@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("https://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` value is prepended to all mock calls, and the `stubs()` method takes a stub
path resource pattern as an argument. In the preceding example, the stub defined at
`/stubs/resource.json` is loaded into the mock server. If the `RestTemplate` is asked to
visit `https://example.org/`, it gets the responses as being declared at that URL. More
than one stub pattern can be specified, and each one can be a directory (for a recursive
list of all ".json"), a fixed filename (as in the example above), or an Ant-style
pattern. The JSON format is the normal WireMock format, which you can read about in the
https://wiremock.org/docs/stubbing/[WireMock website].

Currently, the Spring Cloud Contract Verifier supports 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).

=== Customization of WireMock configuration

You can register a bean of `org.springframework.cloud.contract.wiremock.WireMockConfigurationCustomizer` type
in order to customize the WireMock configuration (e.g. add custom transformers).
Example:

[source,java,indent=0]
----
		@Bean WireMockConfigurationCustomizer optionsCustomizer() {
			return new WireMockConfigurationCustomizer() {
				@Override public void customize(WireMockConfiguration options) {
// perform your customization here
				}
			};
		}
----

=== Generating Stubs using REST Docs

https://projects.spring.io/spring-restdocs[Spring REST Docs] can be used to generate
documentation (for example in Asciidoctor format) for an HTTP API with Spring MockMvc or
Rest Assured. At the same time that you generate documentation for your API, you can also
generate WireMock stubs by using Spring Cloud Contract WireMock. To do so, write your
normal REST Docs test cases and use `@AutoConfigureRestDocs` to have stubs be
automatically generated in the REST Docs output directory. The following code shows an
example:

[source,java,indent=0]
----
@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"));
	}
}
----

This test generates a WireMock stub at "target/snippets/stubs/resource.json". It matches
all GET requests to the "/resource" path.

Without any additional configuration, this tests creates 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. Doing so has two effects:

* Creating a stub that matches only in the way you specify.
* Asserting that the request in the test case also matches the same conditions.

The main entry point for this feature is `WireMockRestDocs.verify()`, which can be used
as a substitute for the `document()` convenience method, as shown in the following
example:

[source,java,indent=0]
----
@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"));
	}
}
----

This contract specifies that any valid POST with an "id" field receives the response
defined in this test. You can chain together calls to `.jsonPath()` to add additional
matchers. If JSON Path is unfamiliar, The https://github.com/jayway/JsonPath[JayWay
documentation] can help you get up to speed.

Instead of the `jsonPath` and `contentType` convenience methods, you can also use the
WireMock APIs to verify that the request matches the created stub, as shown in the
following example:

[source,java,indent=0]
----
	@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. These features can be used to create stubs with a wider
range of parameters. The above example generates a stub resembling the following example:

.post-resource.json
[source,json]
----
{
  "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 you can't use both approaches.

On the consumer side, you can make the `resource.json` generated earlier in this section
available on the classpath (by
https://cloud.spring.io/spring-cloud-contract/spring-cloud-contract.html#_publishing_stubs_as_jars[publishing
stubs as JARs], for example). After that, you can create a stub using WireMock in a
number of different ways, including by using
`@AutoConfigureWireMock(stubs="classpath:resource.json")`, as described earlier in this
document.

=== Generating Contracts by Using REST Docs

You can also generate Spring Cloud Contract DSL files and documentation with Spring REST
Docs. If you do so in combination with Spring Cloud WireMock, you get both the contracts
and the stubs.

Why would you want to use this feature? Some people in the community asked questions
about a 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 lets you generate
the contract files that you can later modify and move to folders (defined in your
configuration) so that the plugin finds them.

TIP: You might wonder why this functionality is in the WireMock module. The functionality
is there because it makes sense to generate both the contracts and the stubs.

Consider the following test:

[source,java]
----
		this.mockMvc.perform(post("/foo")
					.accept(MediaType.APPLICATION_PDF)
					.accept(MediaType.APPLICATION_JSON)
					.contentType(MediaType.APPLICATION_JSON)
					.content("{\"foo\": 23, \"bar\" : \"baz\" }"))
				.andExpect(status().isOk())
				.andExpect(content().string("bar"))
				// first WireMock
				.andDo(WireMockRestDocs.verify()
						.jsonPath("$[?(@.foo >= 20)]")
						.jsonPath("$[?(@.bar in ['baz','bazz','bazzz'])]")
						.contentType(MediaType.valueOf("application/json"))
						.stub("shouldGrantABeerIfOldEnough"))
				// then Contract DSL documentation
				.andDo(document("index", SpringCloudContractRestDocs.dslContract()));
----

The preceding test creates the stub presented in the previous section, generating both
the contract and a documentation file.

The contract is called `index.groovy` and might look like the following example:

[source,groovy]
----
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 (formatted in Asciidoc in this case) contains a formatted
contract. The location of this file would be `index/dsl-contract.adoc`.

== Documentation

You can read more about Spring Cloud Contract Verifier by reading the
{documentation_url}[docs]

== Contributing

:spring-cloud-build-branch: master

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.

=== Sign the Contributor License Agreement
Before we accept a non-trivial patch or pull request we will need you to sign the
https://cla.pivotal.io/sign/spring[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.

=== Code of Conduct
This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of
conduct]. By participating, you  are expected to uphold this code. Please report
unacceptable behavior to spring-code-of-conduct@pivotal.io.

=== Code Conventions and Housekeeping
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.xml` file from the
  https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
  Cloud Build] project. If using IntelliJ, you can use the
  https://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter
  Plugin] to import the same file.
* Make sure all new `.java` files to have a simple Javadoc class comment with at least an
  `@author` tag identifying you, and preferably at least a paragraph on what the class is
  for.
* Add the ASF license header comment to all new `.java` files (copy from existing files
  in the project)
* Add yourself as an `@author` to 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 https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions],
  if you are fixing an existing issue please add `Fixes gh-XXXX` at the end of the commit
  message (where XXXX is the issue number).

=== Checkstyle

Spring Cloud Build comes with a set of checkstyle rules. You can find them in the `spring-cloud-build-tools` module. The most notable files under the module are:

.spring-cloud-build-tools/
----
└── src
    ├── checkstyle
    │   └── checkstyle-suppressions.xml <3>
    └── main
        └── resources
            ├── checkstyle-header.txt <2>
            └── checkstyle.xml <1>
----
<1> Default Checkstyle rules
<2> File header setup
<3> Default suppression rules

==== Checkstyle configuration

Checkstyle rules are *disabled by default*. To add checkstyle to your project just define the following properties and plugins.

.pom.xml
----
<properties>
<maven-checkstyle-plugin.failsOnError>true</maven-checkstyle-plugin.failsOnError> <1>
        <maven-checkstyle-plugin.failsOnViolation>true
        </maven-checkstyle-plugin.failsOnViolation> <2>
        <maven-checkstyle-plugin.includeTestSourceDirectory>true
        </maven-checkstyle-plugin.includeTestSourceDirectory> <3>
</properties>

<build>
        <plugins>
            <plugin> <4>
                <groupId>io.spring.javaformat</groupId>
                <artifactId>spring-javaformat-maven-plugin</artifactId>
            </plugin>
            <plugin> <5>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>

    <reporting>
        <plugins>
            <plugin> <5>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>
    </reporting>
</build>
----
<1> Fails the build upon Checkstyle errors
<2> Fails the build upon Checkstyle violations
<3> Checkstyle analyzes also the test sources
<4> Add the Spring Java Format plugin that will reformat your code to pass most of the Checkstyle formatting rules
<5> Add checkstyle plugin to your build and reporting phases

If you need to suppress some rules (e.g. line length needs to be longer), then it's enough for you to define a file under `${project.root}/src/checkstyle/checkstyle-suppressions.xml` with your suppressions. Example:

.projectRoot/src/checkstyle/checkstyle-suppresions.xml
----
<?xml version="1.0"?>
<!DOCTYPE suppressions PUBLIC
		"-//Puppy Crawl//DTD Suppressions 1.1//EN"
		"https://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
<suppressions>
	<suppress files=".*ConfigServerApplication\.java" checks="HideUtilityClassConstructor"/>
	<suppress files=".*ConfigClientWatch\.java" checks="LineLengthCheck"/>
</suppressions>
----

It's advisable to copy the `${spring-cloud-build.rootFolder}/.editorconfig` and `${spring-cloud-build.rootFolder}/.springformat` to your project. That way, some default formatting rules will be applied. You can do so by running this script:

```bash
$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/.editorconfig -o .editorconfig
$ touch .springformat
```

=== IDE setup

==== Intellij IDEA

In order to setup Intellij you should import our coding conventions, inspection profiles and set up the checkstyle plugin.

.spring-cloud-build-tools/
----
└── src
    ├── checkstyle
    │   └── checkstyle-suppressions.xml <3>
    └── main
        └── resources
            ├── checkstyle-header.txt <2>
            ├── checkstyle.xml <1>
            └── intellij
                ├── Intellij_Project_Defaults.xml <4>
                └── Intellij_Spring_Boot_Java_Conventions.xml <5>
----
<1> Default Checkstyle rules
<2> File header setup
<3> Default suppression rules
<4> Project defaults for Intellij that apply most of Checkstyle rules
<5> Project style conventions for Intellij that apply most of Checkstyle rules

.Code style

image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-code-style.png[Code style]

Go to `File` -> `Settings` -> `Editor` -> `Code style`. There click on the icon next to the `Scheme` section. There, click on the `Import Scheme` value and pick the `Intellij IDEA code style XML` option. Import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Spring_Boot_Java_Conventions.xml` file.

.Inspection profiles

image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-inspections.png[Code style]

Go to `File` -> `Settings` -> `Editor` -> `Inspections`. There click on the icon next to the `Profile` section. There, click on the `Import Profile` and import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Project_Defaults.xml` file.

.Checkstyle

To have Intellij work with Checkstyle, you have to install the `Checkstyle` plugin. It's advisable to also install the `Assertions2Assertj` to automatically convert the JUnit assertions

image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-checkstyle.png[Checkstyle]

Go to `File` -> `Settings` -> `Other settings` -> `Checkstyle`. There click on the `+` icon in the `Configuration file` section. There, you'll have to define where the checkstyle rules should be picked from. In the image above, we've picked the rules from the cloned Spring Cloud Build repository. However, you can point to the Spring Cloud Build's GitHub repository (e.g. for the `checkstyle.xml` : `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle.xml`). We need to provide the following variables:

- `checkstyle.header.file` - please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/main/resources/checkstyle/checkstyle-header.txt` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` URL.
- `checkstyle.suppressions.file` - default suppressions. Please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` URL.
- `checkstyle.additional.suppressions.file` - this variable corresponds to suppressions in your local project. E.g. you're working on `spring-cloud-contract`. Then point to the `project-root/src/checkstyle/checkstyle-suppressions.xml` folder. Example for `spring-cloud-contract` would be: `/home/username/spring-cloud-contract/src/checkstyle/checkstyle-suppressions.xml`.

IMPORTANT: Remember to set the `Scan Scope` to `All sources` since we apply checkstyle rules for production and test sources.

== How to build it

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.

IMPORTANT: Spring Cloud Contract builds Docker images. Remember to
have Docker installed.

=== Project structure

Here you can find the Spring Cloud Contract folder structure

```
├── docker
├── 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
```

 - `docker` - folder contains docker images
 - `samples` - folder contains test samples together with standalone ones used also to build documentation
 - `scripts` - contains scripts to build and test `Spring Cloud Contract` with 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 for `Spring Cloud Contract Verifier`
 - `spring-cloud-contract-verifier` - core of the `Spring Cloud Contract Verifier` functionality
 - `spring-cloud-contract-wiremock` - all WireMock related functionality
 - `tests` - integration tests for different messaging technologies

=== Commands

To build the core functionality together with Maven Plugin you can run

```
./mvnw clean install -P integration
```

Calling 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 build
```

=== Helpful scripts

We'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.sh
```

and with 8 cores

```
CORES=8 ./scripts/parallelBuild.sh
```

To build the project without any integration tests (by default uses 1 core)

```
./scripts/noIntegration.sh
```

and with 8 cores

```
CORES=8 ./scripts/noIntegration.sh
```

To generate the documentation (both the root one and the maven plugin one)

```
./scripts/generateDocs.sh
```
