[FIXED] Why `fail` inside `catch(Exception ex)` handling `assertEquals` is not called?

Issue

I had the question some minutes before but I want to try something else..

For Example I have this method:

//inside Number.java
public static int add(int nr1, int nr2) {
    return nr2 + nr2;
}

As you see I return number2 + number2

In my Test I use that it would throw the error that it was expected 9 instead of the number which was calculate in the main method.

@Test
public void test() throws Exception {
    int nr1 = 4;
    int nr2 = 5;
    int sum = Number.add(nr1, nr2);
    assertEquals(9, sum);
}

I tried this now to get an message if the program fails but it doesn´t with fail..

@Test
public void test() throws Exception {
    int nr1 = 4;
    int nr2 = 5;
    int sum = Number.add(nr1, nr2);
    
    try {
        assertEquals(9, sum);
    }catch(Exception e) {
        fail("Are you sure you calculate the right numbers?");
    }
}

But the program is only showing me the AssertionError not the Message in fail()

I know now that I can use it this way:

assertEquals("...",9,sum);

but I don't want this AssertionError:

expected:<> but was <> 

at the end

Solution

An AssertionError extends Error which implements Throwable. Your

catch(Exception e)

is useless because the AssertionError is not an Exception.

Catch it directly using catch(AssertionError e) if you must, but usually Errors are not supposed to be caught.

If you really want to force a call to fail, avoid the assertEquals and just use

if(sum != 9) {
  fail("Are you sure you calculate the right numbers?");
}

which avoids the AssertionError altogether.

Answered By - f1sh
Answer Checked By - David Marino (JavaFixing Volunteer)