FindLargestProductTest

import junit.framework.TestCase;

public class FindLargestProductTest extends TestCase {

    public void testOriginalCase() {
        final int[] inputArray = {3, 6, -2, -5, 7, 3};
        final int largestProduct = FindLargestProduct.adjacentElementsProduct(inputArray);
        assertEquals("7 * 3 = ", 21, largestProduct);
    }

    public void testNegativeResult() {
        final int[] inputArray = {3, -2, 6, -5, 7, -3};
        final int largestProduct = FindLargestProduct.adjacentElementsProduct(inputArray);
        assertEquals("3 * -2 = ", -6, largestProduct);
    }

    public void testTwoElementArray() {
        final int[] inputArray = {3, 4};
        final int largestProduct = FindLargestProduct.adjacentElementsProduct(inputArray);
        assertEquals("3 * 4 = ", 12, largestProduct);
    }

    public void testOneElementArray() {
        final int[] inputArray = {6};
        try {
            //noinspection ResultOfMethodCallIgnored
            FindLargestProduct.adjacentElementsProduct(inputArray);
            fail("Expected IllegalArgumentException.");
        } catch (final IllegalArgumentException ex) {
            assertEquals("Minimum array size is two elements.", ex.getMessage());
        }
    }

    public void testEmptyInputArray() {
        final int[] inputArray = {};
        try {
            //noinspection ResultOfMethodCallIgnored
            FindLargestProduct.adjacentElementsProduct(inputArray);
            fail("Expected IllegalArgumentException.");
        } catch (final IllegalArgumentException ex) {
            assertEquals("Minimum array size is two elements.", ex.getMessage());
        }
    }

    public void testNullInputArray() {
        try {
            //noinspection ResultOfMethodCallIgnored
            FindLargestProduct.adjacentElementsProduct(null);
            fail("Expected IllegalArgumentException.");
        } catch (final IllegalArgumentException ex) {
            assertEquals("Input array must not be null.", ex.getMessage());
        }
    }

}