TestRestTemplate for API testing in JUnit - Test Execution Trace

Test Overview

This test uses TestRestTemplate to call a REST API endpoint and verifies that the response status is 200 OK and the response body contains the expected message.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import static org.junit.jupiter.api.Assertions.assertEquals;

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class ApiTest {

    @Autowired
    private TestRestTemplate restTemplate;

    @Test
    public void testHelloEndpoint() {
        ResponseEntity<String> response = restTemplate.getForEntity("/hello", String.class);
        assertEquals(200, response.getStatusCodeValue());
        assertEquals("Hello, World!", response.getBody());
    }
}

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	JUnit test runner initializes Spring Boot test context with random port	-	PASS
2	TestRestTemplate sends GET request to '/hello' endpoint	HTTP request sent to local server at random port	-	PASS
3	Server processes request and returns HTTP 200 with body 'Hello, World!'	Response received by TestRestTemplate	-	PASS
4	Test asserts that response status code is 200	Response status code is 200	assertEquals(200, response.getStatusCodeValue())	PASS
5	Test asserts that response body equals 'Hello, World!'	Response body is 'Hello, World!'	assertEquals("Hello, World!", response.getBody())	PASS
6	Test ends successfully	All assertions passed	-	PASS

Failure Scenario

Failing Condition: The '/hello' endpoint returns a status other than 200 or a different response body

Execution Trace Quiz - 3 Questions

What does the test verify about the API response?

A The response status is 200 and body is 'Hello, World!'

B The response status is 500 and body is empty

C The response contains JSON data

D The response status is 404

Key Result

Always verify both the HTTP status code and the response body content to ensure the API behaves as expected.