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Learn REST and SOAP API Test Automation in Java

File Downloads

Understand how to automate file downloads in REST API testing by making GET requests, saving JSON response bodies as files, and validating their content and existence. This lesson guides you through practical steps using Rest Assured and TestNG for effective test automation.

We'll cover the following...

What is file download?

There are instances where we need to save the response body message as a file. In this example, we will make a GET request that returns a JSON string which will be saved as a file.

Example: Download JSON file

  • HTTP method: GET
  • Target URL: http://ezifyautomationlabs.com:6565
  • Resource path: /educative-rest/students

Take a look at the code below:

Java
import static org.testng.Assert.assertEquals;

import static org.testng.Assert.assertTrue;



import java.io.File;

import java.io.IOException;

import java.nio.file.Files;



import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.testng.annotations.Test;



import io.restassured.RestAssured;

import io.restassured.response.Response;



public class APIDemo {



	private static final Logger LOG = LoggerFactory.getLogger(APIDemo.class);



	@Test

	public void testDownload() throws IOException {



		String url = "http://ezifyautomationlabs.com:6565/educative-rest/students";



        // making API call

		Response response = RestAssured.given()

				.log().all(true)

				.get(url)

				.andReturn();



        // validating http status code

		assertEquals(response.getStatusCode(), 200, "http status code");



        // reading the response boody as byte[]

		byte[] bytes = response.getBody().asByteArray();

        // validating that the response content length > 0

		assertTrue(bytes.length > 0, "response content length is 0");



        // writing the byte[] to file

		File file = new File("students.json");

		Files.write(file.toPath(), bytes);



        // validating the existence and size of file

		assertTrue(file.exists(), "file " + file + " does not exist");

		assertTrue(file.length() > 0, "file size is 0");

        assertEquals(bytes.length, file.length(), "file size and response content");



		String content = new String(Files.readAllBytes(file.toPath()));

		LOG.info("printing content of the file => {}", content);

	}



}

The output of this code returns the following ...