How to explicitly or manually fail a test case in JUnit

In my Java / RestAssured / TestNG framework, I want to write an assertion with the following structure

if(responseString.equals("Good Response!")) {
  // perform additional assertions here
} else if(responseString.equals("Bad Response!")) {
  // just fail the test case right here and now
}

What is the best way to go about simply failing the test case without asserting anything else?

Answer

Don’t use the if, instead just do:

assertEquals("Good Response!", responseString);
// perform additional assertions here

If you simply want to fail:

fail("I failed because...");