Can you tell me how I find that? I have Java selected at the top when I went into this discussion.

So it looks like the reason this works is because of the test method assertArrayEquals();

private void assertArrayEquals(double []expecteds, double[] actuals) {
        for(int i = 0; i < actuals.length; i++)
            assertEquals(expecteds[i], actuals[i], 1e-10);
}

If actual's length is 0, the loop doesn't enter and no checks are done.