Spring Cloud Contract With Spring Boot | Spring Cloud Contract

Introduction

Spring Cloud Contract is a framework that helps to implement Consumer Driven Contracts (CDC). It facilitates the development process by ensuring that the service provider and consumer are aligned through contracts. This tutorial will guide you through the process of setting up Spring Cloud Contract with Spring Boot, from initial setup to testing and executing contracts.

Prerequisites

Before you start, ensure you have the following prerequisites:

Java Development Kit (JDK) 8 or higher
Maven or Gradle build tool
Basic understanding of Spring Boot
IDE like IntelliJ IDEA or Eclipse

Setting Up the Project

We will create a simple Spring Boot application and integrate Spring Cloud Contract into it. You can use Spring Initializr or your IDE to set up the project. Below is how to do it using Spring Initializr.

1. Create a Spring Boot Application

Navigate to Spring Initializr and configure your project:

Project: Maven Project
Language: Java
Spring Boot: 2.5.x or later
Dependencies: Spring Web, Spring Cloud Contract Verifier

Click on "Generate" to download the project.

Implementing a Simple API

Next, let's implement a simple REST API in our Spring Boot application.

2. Create a REST Controller

Add a new class called GreetingController.java in the package com.example.demo:

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public String greet(@RequestParam(value = "name", defaultValue = "World") String name) {
        return "Hello, " + name + "!";
    }
}

Creating Contracts

Now, we will create a contract for our REST API. Contracts are written in Groovy DSL.

3. Create a Contract File

Create a new directory src/test/resources/contracts and create a file named greet.groovy inside it:

import org.springframework.cloud.contract.spec.Contract

Contract.make {
    description "should return greeting message"
    request {
        method GET()
        url("/greet?name=John")
    }
    response {
        status 200
        body("Hello, John!")
        headers {
            contentType(applicationJson())
        }
    }
}

Running Tests

Spring Cloud Contract will automatically generate tests from the contract. To run the tests, you can execute the following command in your project directory:

mvn clean test

This will validate the contract against the implementation. Ensure that the tests pass successfully.

Conclusion

In this tutorial, we have covered the basics of setting up Spring Cloud Contract with Spring Boot. We created a simple REST API and defined a contract for it. By following these practices, you can ensure that your services are reliable and well-tested.

For more advanced features and configurations, consider exploring the Spring Cloud Contract documentation available at Spring Cloud Contract.

Spring Cloud Contract with Spring Boot Tutorial