Why does my JUnit test for this set of codes always return errors?

Question

I'm trying to write the Junit test code for the following code:

public class RateofPay {

   public double totalSalary(double work, double work2, double hour1, double hour2, double hour3) {

    double salary1 = work * hour1;
    double salary2 = work2 * hour2;
    double salary3 = work * hour3;
    double wages = salary1 + salary2 + salary3;
    return wages;
    }
  }

And this is the JUnit test I have wrote:

public class WageTest {

@Test
public void testWage() {
    RateofPay test=new RateofPay();
    double result=test.totalSalary(1.0, 2.0, 3.0, 4.0, 5.0);
    assertEquals(12.0, result);

}

@Test
public void testWage1() {
    RateofPay test=new RateofPay();
    double result=test.totalSalary(6.0, 7.0, 8.0, 9.0, 10.0);
    assertEquals(157.0, result);

 }
}

The problem is that every time when I run the JUnit test, none of them pass the test. The result says

assertEquals(expected, actual, delta) to compare floating point number.

I'm wondering what is wrong? Thanks.

more details regarding the delta are available on http://stackoverflow.com/questions/5939788/junit-assertequalsdouble-expected-double-actual-double-epsilon — Ashish Juyal, Feb 09 '17 at 07:14
Hint: the **real** solution here is: do some research on your error message. You already had **all** the information you need at hand. When JUnit tells you "please do X"; then heck: go and google what "X" is about. In essence, your problem is that you do not understand how computers deal with floating point numbers; and thus you do not understand how to write code dealing with floating point numbers. So: simply step back, turn to the books and **learn** about "computers & floating point numbers". You can start reading the "duplicated" question I put up; esp. response 3 by madma is for you ... — GhostCat, Feb 09 '17 at 07:52

score 4 · Answer 1 · answered Feb 09 '17 at 02:42

You should specify the delta parameter when trying to compare double numbers. Besides, your assertions are wrong.

They should be like this.

    @Test
    public void testWage() {
        Solution test=new Solution();
        double result=test.totalSalary(1.0, 2.0, 3.0, 4.0, 5.0);
        assertEquals(16.0, result, 0.0);
    }

    @Test
    public void testWage1() {
        Solution test=new Solution();
        double result=test.totalSalary(6.0, 7.0, 8.0, 9.0, 10.0);
        assertEquals(171.0, result, 0.0);

    }

For example, the first test would have this calculation:

double salary1 = 1 * 3; //3
double salary2 = 2 * 4; //8
double salary3 = 1 * 5; //5
double wages = salary1 + salary2 + salary3; // 3 + 8 + 5 = 16

You could have mentioned at least in a half-sentence *why* one needs to use some *epsilon* when comparing floating point numbers in general. — GhostCat, Feb 09 '17 at 07:54

Why does my JUnit test for this set of codes always return errors?

1 Answers1