ArmstrongTest

package p20190916;

import junit.framework.TestCase;

import java.util.TreeSet;

public class ArmstrongTest extends TestCase {

    public void testKnownArmstrongNumbersBetween0and999() {
        final TreeSet<Integer> armstrongNumbers = new TreeSet<>();
        assertIsArmstrongNumber(armstrongNumbers, 0);
        assertIsArmstrongNumber(armstrongNumbers, 1);
        assertIsArmstrongNumber(armstrongNumbers, 153);
        assertIsArmstrongNumber(armstrongNumbers, 370);
        assertIsArmstrongNumber(armstrongNumbers, 371);
        assertIsArmstrongNumber(armstrongNumbers, 407);

        for (int otherNumber = 0; otherNumber <= 999; ++otherNumber) {
            if (!armstrongNumbers.contains(otherNumber)) {
                assertFalse(otherNumber + " should *NOT* be an Armstrong number", NumberFinder.isArmstrong(otherNumber));
            }
        }
    }

    private static void assertIsArmstrongNumber(TreeSet<Integer> armstrongNumbers, int armstrongNumber) {
        assertTrue(armstrongNumber + " should be Armstrong number", NumberFinder.isArmstrong(armstrongNumber));
        armstrongNumbers.add(armstrongNumber);
    }
}