Writing documentation for RESTful APIs is an essential part of the development process. It helps developers and consumers understand the functionality and usage of the API endpoints. In this blog post, we will explore how to generate comprehensive documentation for RESTful APIs using Java Spring REST Docs.

What is Java Spring REST Docs?

Java Spring REST Docs is a library that provides documentation support for RESTful APIs implemented with the Spring framework. It allows you to generate documentation directly from your API tests, ensuring that your documentation stays in sync with your actual API implementation.

Getting Started

To get started with Java Spring REST Docs, you need to add the necessary dependencies to your project. Open your pom.xml file for Maven or build.gradle file for Gradle and add the following dependencies:

<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-core</artifactId>
    <version>{version}</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.restdocs</groupId>
    <artifactId>spring-restdocs-mockmvc</artifactId>
    <version>{version}</version>
    <scope>test</scope>
</dependency>

Replace {version} with the latest version of Spring REST Docs.

Writing Documentation Tests

Once you have set up the dependencies, you can start writing documentation tests. Documentation tests are written using JUnit or any other testing framework of your choice. You can use the Spring MVC MockMvc to make requests to your API endpoints and document the responses.

Here’s an example documentation test for a GET request:

import org.junit.jupiter.api.Test;
import org.springframework.restdocs.mockmvc.MockMvcRestDocumentation;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.documentationConfiguration;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.snippets;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

public class ApiDocumentationTest {

    private MockMvc mockMvc;

    @Test
    public void documentationTest() throws Exception {
        this.mockMvc = MockMvcBuilders.standaloneSetup(new MyController())
                .apply(documentationConfiguration())
                .build();

        mockMvc.perform(get("/api/endpoint"))
                .andExpect(status().isOk())
                .andDo(document("endpoint",
                        snippets(
                                // Add snippets for request and response fields
                        )
                ));
    }
}

Generating Documentation

To generate the API documentation, you need to run the documentation tests. When the tests execute, Spring REST Docs generates snippets for each API endpoint based on the configured snippets. These snippets can then be transformed into various formats such as HTML, PDF, or markdown.

By default, Spring REST Docs generates ASCIIDoc snippets, which can be converted to other formats using tools like Asciidoctor. You can also use pre-configured plugins for popular formats like Swagger or RAML to generate API documentation.

Conclusion

Java Spring REST Docs provides a convenient way to generate documentation for your RESTful APIs. By writing documentation tests alongside your API tests, you ensure that the documentation stays up-to-date with your API implementation. With its flexibility and ease of use, Spring REST Docs is a valuable tool for documenting your APIs.

#JavaSpring #RESTDocs