如何使用同一junit测试多个Java文件？

Question

How can i test several .java files(that implements the same method in different ways) with one unit test? For example, i have a folder with different .java files(or different folders with the same name .java file), how can i select all of them to run it? right now i need to select each time one of them and move it to the same folder with the unit test and run it. Thanks.

Edit: I think i wasn't clear enough, so i will give more example:

I have files aa.java and bb.java, which both have the method "static public int fibonacci(int x)", i want to create a unit test, that will use aa and bb methods and see if they work properly(assertEquals(result, expected)). PS i have more then only 2 files with the same method.

Answer 1

Assuming you want to adhere to DRY , write a utility method to do the testing, and have a unit test(s) call it.

Eg

private static void assertFibonacci(IntUnaryOperator op) {
    int n = 5;
    int expected = 8;
    // or a loop of values, whatever
    assert op.applyAsInt(n) == expected;
}

Then in your unit test:

@Test
public void testX() {
    assertFibonacci(new aa()::fibonacci);
    assertFibonacci(new bb()::fibonacci);
}

Or better, use separate Test methods, so errors in each are reported separately:

@Test
public void testAA() {
    assertFibonacci(new aa()::fibonacci);
}

@Test
public void testBB() {
    assertFibonacci(new bb()::fibonacci);
}

Answer 2

The Spock Framework , which runs on top of JUnit, has much better support for parameterized testing , which is what you seem to want, than either plain JUnit or TestNG.

If you can't use Spock, you can either use JUnit Parameterized and supply an instance of each of your classes as your data set, or (my recommendation) write all your common unit tests in an abstract base class WidgetTests with a method protected abstract Widget getInstance() and subclass for each kind of widget. This will still end up with multiple classes, but you won't repeat your test cases, and it allows you to write additional implementation-specific tests in an organized way.