TestRestTemplate for API testing in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the test result of this TestRestTemplate GET request?

Consider this JUnit test using TestRestTemplate to call a REST API endpoint that returns a JSON with a message.
What will be the value of response.getBody() after this test runs?

JUnit

ResponseEntity<String> response = testRestTemplate.getForEntity("/api/greet", String.class);
String body = response.getBody();

A "{message:Hello World}"

B null

C "Hello World"

D "{\"message\":\"Hello World\"}"

💡 Hint

The API returns a JSON string with a message field.

The getForEntity method returns the full JSON string as a String body, including quotes and escaped characters.

❓ assertion

intermediate

Which assertion correctly verifies the HTTP status code 200?

You want to check that the response status code from TestRestTemplate is HTTP 200 OK.
Which assertion is correct in JUnit 5?

JUnit

ResponseEntity<String> response = testRestTemplate.getForEntity("/api/data", String.class);

A assertEquals(HttpStatus.OK, response.getStatusCode());

B assertTrue(response.getStatusCode() == 200);

C assertEquals(200, response.getStatusCodeValue());

D assertEquals("200", response.getStatusCode().toString());

💡 Hint

HttpStatus.OK is an enum constant representing 200.

The getStatusCode() returns an HttpStatus enum, so comparing with HttpStatus.OK is correct.

❓ locator

advanced

Which URI template is correct for a path variable in TestRestTemplate?

You want to call an API endpoint with a path variable userId using TestRestTemplate.
Which URI template and call is correct?

A testRestTemplate.getForEntity("/users/:userId", String.class, 42);

B testRestTemplate.getForEntity("/users/{userId}", String.class, 42);

C testRestTemplate.getForEntity("/users/$userId", String.class, 42);

D testRestTemplate.getForEntity("/users/?userId=42", String.class);

💡 Hint

TestRestTemplate uses curly braces {} for path variables.

The correct syntax for path variables is using {variableName} in the URI template.

🔧 Debug

advanced

Why does this POST request test fail with 415 Unsupported Media Type?

This test sends a POST request with a JSON body but fails with HTTP 415 error.
What is the likely cause?

JUnit

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> request = new HttpEntity<>("{\"name\":\"Test\"}", headers);
ResponseEntity<String> response = testRestTemplate.postForEntity("/api/users", request, String.class);

A The HttpEntity is missing the Accept header.

B The JSON string is malformed and causes parsing error.

C The server expects a different Content-Type header than application/json.

D The testRestTemplate instance is not initialized properly.

💡 Hint

415 means the server does not support the media type sent.

If the server expects a different Content-Type, it rejects application/json with 415.

❓ framework

expert

How to configure TestRestTemplate to use Basic Authentication in a Spring Boot test?

You want to test a secured API endpoint that requires Basic Auth using TestRestTemplate.
Which code snippet correctly configures TestRestTemplate with username 'user' and password 'pass'?

A TestRestTemplate testRestTemplate = new TestRestTemplate("user", "pass");

B

TestRestTemplate testRestTemplate = new TestRestTemplate();
testRestTemplate.getRestTemplate().getInterceptors().add(new BasicAuthenticationInterceptor("user", "pass"));

C

TestRestTemplate testRestTemplate = new TestRestTemplate();
testRestTemplate.setBasicAuth("user", "pass");

D

TestRestTemplate testRestTemplate = new TestRestTemplate();
testRestTemplate.getRestTemplate().setBasicAuth("user", "pass");

💡 Hint

TestRestTemplate has a constructor that accepts username and password.

The simplest way is to use the constructor with username and password parameters.