Java.lang.assertionerror: content type not set

Explanation of java.lang.AssertionError: content type not set

An AssertionError with the message “content type not set” usually occurs when the expected content type was not set in the response headers during a Java program execution. This error is usually encountered when working with HTTP requests and responses.

Example:

Let’s consider an example where we make an HTTP request to a server and expect a response with a specific content type, such as JSON. If the server does not set the “content-type” header properly or if the expected content type does not match the actual content type in the response, an AssertionError will be thrown.

    
import org.junit.Test;
import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;

public class MyAPITest {

    @Test
    public void testAPIResponseContentType() {
        given()
            .when()
            .get("https://api.example.com/users")
            .then()
            .assertThat()
            .contentType("application/json"); // Expecting JSON content type
    }
}
    
  

In the above example, we are using the RestAssured library to make an HTTP GET request to “https://api.example.com/users”. We then use the “assertThat().contentType()” method to check if the response content type is “application/json”. If the actual content type is not equal to “application/json”, an AssertionError will be thrown with the message “content type not set”.

To resolve this issue, make sure that the server sets the “content-type” header correctly in the response, matching the expected content type. Also, ensure that the expected content type provided in the test case is correct.