When working with REST APIs, particularly those that allow file uploads, you often need to send multipart/form-data requests. REST Assured makes this process straightforward. Below, we’ll look at a simple example of how to send a multipart file using REST Assured.

Step 1: Add Dependencies

First, ensure that your project includes the necessary dependencies for REST Assured. If you're using Maven, you can add the following to your pom.xml:

<dependency>
    <groupId>io.rest-assured</groupId>
    <artifactId>rest-assured</artifactId>
    <version>5.3.0</version> <!-- Check for the latest version -->
    <scope>test</scope>
</dependency>

Step 2: Prepare Your Test Class

In your test class, you’ll need to create a method to upload the multipart file. Here’s how it could look:

import io.restassured.RestAssured;
import io.restassured.http.ContentType;
import static io.restassured.RestAssured.*;

import java.io.File;

public class FileUploadTest {

    public void uploadFile() {
        // Step 3: Define the file you want to upload
        File file = new File("path/to/your/file.txt"); // Specify the path to your file

        // Step 4: Send multipart request
        given()
            .baseUri("https://your-api-endpoint.com") // API Endpoint
            .basePath("/upload") // Specific path for the upload
            .contentType(ContentType.MULTIPART) // Specify the content type
            .multiPart("file", file) // Add the file as multipart
        .when()
            .post() // Use POST method to upload
        .then()
            .statusCode(200) // Verify expected HTTP response status
            .log().all(); // Log the response details
    }
}

Step 3: Breaking Down the Code

1. Import Statements: Here, we import the necessary classes from the REST Assured library and Java's file handling.

2. File Specification: Use new File("path/to/your/file.txt") to locate the file you want to upload. Make sure the path is correct.

3. Building the Request:

   • given() starts the process of defining your request.
   • baseUri() sets the base URL of the API.
   • basePath() defines the specific path for the file upload.
   • contentType(ContentType.MULTIPART) specifies that you are sending a multipart request.
   • multiPart("file", file) adds the file to the request, where "file" is the name expected by the server.

4. Sending the Request:

   • The when() method prepares to execute the request. Here, we use post() to make a POST request to the specified endpoint.
   • The then() method is used to validate the response. In this example, we check that the response has a 200 status code, indicating a successful upload.

5. Logging: log().all() will output the details of the response for easier debugging.

Step 4: Run Your Test

Now that you have implemented the code, you can run your test within your Java IDE or a test runner. If everything is set up correctly, it should initiate an upload of the specified file to your designated server.

By following these steps, you can effortlessly send multipart files using REST Assured in your Java applications. Enjoy streamlined file uploads and robust API testing!