How does JUnit find tests?

Question

I had assumed that JUnit found tests (inside classes derived from junit.framework.TestCase) by looking for methods annotated with @Test. However, I've included a test from http://256stuff.com/sources/jenkins_hash_java/JenkinsHashTest.java in a project. The structure of the code is as follows:

import junit.framework.TestCase;

public class JenkinsHashTest extends TestCase {
    public void testHashes() {
        ...//this code is run
    }   
}

I have confirmed that the test method testHashes() is run despite not being annotated with @Test. In case it's relevant, I'm invoking all of this via gradle test.

Answer 1

You can refer to this Junit 3 vs Junit 4 Comparison:

Basically, in JUnit 3 you need to extend junit.framework.TestCase. All test cases need to follow the testXXX pattern.

JUnit 4 removes that restrictions. Any public classes with a zero-argument public constructor can act as a test class. Any methods which need consider as a test method should be annotated with the @Test annotation.