White Box Testing: Test Equivalence Classes
The strategy of testing representative values from equivalence classes
still applies to white box testing. We break up the possible inputs for
each parameter into equivalence classes and test representative values
for each parameter. There are two parameters for
Paycheck.calculateRegularPay(): the pay rate and the hours worked. For
the hours worked, the equivalence classes are hours less than 0, hours
between 0 and 40, and hours greater than 40. Since we are focusing on
representative values, we can choose values that are away from 40. Good
representative values would be 36 and 46, shown in Figure 7.
/**
* Test the Paycheck.calculateRegularPay() method.
*/
@Test
public void testCalculateRegularPay() {
// Less than 40 hours
// Regular Level 1 36 hours
assertEquals("Paycheck.calculateRegularPay(Paycheck.LEVEL_1_PAY_RATE, 36)", 68400,
Paycheck.calculateRegularPay(Paycheck.LEVEL_1_PAY_RATE, 36));
// Over 40 hours
// Regular Level 1 46 hours
assertEquals("Paycheck.calculateRegularPay(Paycheck.LEVEL_1_PAY_RATE, 46)", 76000,
Paycheck.calculateRegularPay(Paycheck.LEVEL_1_PAY_RATE, 46));
}
Figure 7: Equivalence class tests for Paycheck.calculateRegularPay() in PaycheckTest.