Question

I’m writing a JUnit test method for a Clock class to ensure that the toString representation of the object returns in the format that I want it to. So, I’ve overriden the toString() and written it as it want it to be represented but when I compare it with the format I expect in JUnit it fails with the following:

org.junit.ComparisonFailure: expected: < Time : 10:0[0:0]0 > but was:< Time : 10:0[:]0>

Why is the symbols [ and ] being displayed here? Is it some part of the toString() representation which I do not know about? Relevant code is below:

JUnit:

    @Test
public void testFormattingOfTimeIsDisplayedCorrectly() {

    final byte TEN = 10;
    final byte DBL_ZERO = 00;

    clock.setTime(TEN, DBL_ZERO, DBL_ZERO);

    final String EXPECTED_STRING = "Time : 10:00:00";

    assertEquals(EXPECTED_STRING, clock.toString());    

}

toString() in Clock class:

@Override
public String toString() {
    return "Time : " + hours + ":" + minutes + ":" + seconds;
}

and the setTime method also in Clock class:

public void setTime(byte hour, byte minutes, byte seconds) {

    this.hours = hour;
    this.minutes = minutes;
    this.seconds = seconds;

}

I’m wondering, maybe it has something to do with using byte? Or is it just something with what toString() returns that I don’t understand. I’m just puzzled about why my JUnit method don’t see them as the same format.

Answer 1

Replace by the line:

return "Time : " + String.format("%02d", hours) + ":" + String.format("%02d", minutes) + ":" + String.format("%02d", seconds);