JUnit testing for assertEqual NullPointerException

I am not sure why the test case doesn't have an output of `true`. Both cases should give a `NullPointerException`. I've tried doing this (Not exactly the same but it gives and output of `true`) : ``` String nullStr = null; //@Test public int NullOutput1() { nullStr.indexOf(3); return 0; } //@Test(expected=NullPointerException.class) public int NullOutput2() { nullStr.indexOf(2); return 0; } @Test(expected=NullPointerException.class) public void testboth() { assertEquals(NullOutput1(), NullOutput2()); } ``` Runner: ``` import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunnerStringMethods { public static void main(String[] args) { Result result = JUnitCore.runClasses(TestJunitMyIndexOf.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } } ``` Method: ``` public static int myIndexOf(char[] str, int ch, int index) { if (str == null) { throw new NullPointerException(); } // increase efficiency if (str.length <= index || index < 0) { return -1; } for (int i = index; i < str.length; i++) { if (index == str[i]) { return i; } } // if not found return -1; } ``` Test Case: ``` @Test(expected=NullPointerException.class) public void testNullInput() { assertEquals(nullString.indexOf(3), StringMethods.myIndexOf(null, 'd',3)); } ```