UtilTest.java

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

/**
 * The test class UtilTest.
 *
 * @author  gcschmit
 * @version 03jun2020
 */
public class UtilTest
{
    /**
     * Default constructor for test class UtilTest
     */
    public UtilTest()
    {
    }

    /**
     * Sets up the test fixture.
     *
     * Called before every test case method.
     */
    @BeforeEach
    public void setUp()
    {
    }

    /**
     * Tears down the test fixture.
     *
     * Called after every test case method.
     */
    @AfterEach
    public void tearDown()
    {
    }
    
    @Test
    public void testRandRange()
    {
        for(int i = 0; i < 1000; i++)
        {
            int value = Util.randRange(5, 15);
            assertTrue((value >= 5 && value < 15), "value (" + value + ") must be in the range [5, 15)");
        }
        
        final int MIN = 5;
        final int MAX = 15;
        final int RANGE = MAX-MIN;
        final int ITERATIONS = 100000;     
        final int TOLERANCE = ITERATIONS / 20;
        
        int[] frequencies = new int[RANGE];
        for(int i = 0; i < ITERATIONS; i++)
        {
            frequencies[Util.randRange(MIN, MAX) - MIN]++;
        }
        for(int i = 0; i < RANGE; i++)
        {
            assertEquals(ITERATIONS / RANGE, frequencies[i], TOLERANCE,
                    "value (" + (i+MIN) + ") wasn't generated with the expected frequency");
        }
    }
    
    @Test
    public void testCount()
    {
        int[] testArray = new int[] { 0, 1, 2, 3, 4, 4, 6, 7, 4, 9 };
        
        // test if value never occurs in array
        assertEquals(0, Util.count(testArray, 10, 0, 10), "10 isn't in the array");
        
        // test if value occurs once at start of array/range
        assertEquals(1, Util.count(testArray, 0, 0, 10), "0 is the first element in the array");
        
        // test if value occurs once at end of array/range
        assertEquals(1, Util.count(testArray, 9, 0, 10), "9 is the last element in the array");
        
        
        testArray = new int[] { 0, 1, 2, 0, 4, 4, 9, 7, 4, 9 };
        
        // test if value occurs 2 times (including at start)
        assertEquals(2, Util.count(testArray, 0, 0, 10), "0 occurs twice in the array");
        
        // test if value occurs 2 times (including at end)
        assertEquals(2, Util.count(testArray, 9, 0, 10), "9 occurs twice in the array");
        
        // test if value occurs 3 times (including twice in a row)
        assertEquals(3, Util.count(testArray, 4, 0, 10), "4 occurs twice in the array (in a row)");
        
        
        testArray = new int[] { 9, 1, 2, 0, 9, 4, 9, 7, 4, 9 };
        
        // test if value occurs within subset of array
        assertEquals(2, Util.count(testArray, 9, 4, 7), "9 only occurs twice in the specified range");
    }
}