Testing Differences by Testing Similarities

ColorTest.java

package com.tomkel;

import org.testng.Assert;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

@Test
public class ColorTest {

    public enum Temperature {
        WARM,
        COLD;
    }

    public class WavelengthRange {
        public float lowerBoundary;
        public float upperBoundary;

        public WavelengthRange(float lowerBoundary, float upperBoundary) {
            this.lowerBoundary = lowerBoundary;
            this.upperBoundary = upperBoundary;
        }
    }

    private class Color {

        public String name;
        public int number;
        public boolean primary;
        public Temperature temperature;
        public String[] variants;
        public WavelengthRange wavelengthRange;

        public Color(String name, int number, boolean primary, Temperature temperature, String[] variants, WavelengthRange wavelengthRange) {
            this.name = name;
            this.number = number;
            this.primary = primary;
            this.temperature = temperature;
            this.variants = variants;
            this.wavelengthRange = wavelengthRange;
        }
    }


    @Test(dataProvider = "same")
    public void testSame(Color actual, Color expected) {

        // These are pretty normal
        Assert.assertEquals(actual.name, expected.name);
        Assert.assertEquals(actual.number, expected.number);
        Assert.assertEquals(actual.primary, expected.primary);
        Assert.assertEquals(actual.temperature, expected.temperature);

        // A little bit more complex...
        // Check if the lengths are the same:
        Assert.assertEquals(actual.variants.length, expected.variants.length);
        // Make sure everything in "expected" is reflected in "actual":
        for (String expectedVariant : expected.variants) {
            boolean found = false;
            for (String actualVariant : actual.variants) {
                if (actualVariant.equals(expectedVariant)) {
                    found = true;
                }
            }
            Assert.assertTrue(found, String.format("Missing '%s' in actual variants", expectedVariant));
        }
        // Then do the reverse:
        for (String actualVariant : expected.variants) {
            boolean found = false;
            for (String expectedVariant : expected.variants) {
                if (expectedVariant.equals(actualVariant)) {
                    found = true;
                }
            }
            Assert.assertTrue(found, String.format("Missing '%s' in expected variants", actualVariant));
        }

        // Yikes... Getting really complex... I think you get the point, so I won't even bother here...
        // Assert.assertEquals(actual.wavelengthRange, expected.wavelengthRange);
    }

    @DataProvider(name = "same")
    public Object[][] same() {
        return new Object[][] {
                {
                        new Color("blue", 5, true, Temperature.COLD, new String[] {"aqua", "turquoise"}, new WavelengthRange(450f, 495f)),
                        new Color("blue", 5, true, Temperature.COLD, new String[] {"aqua", "turquoise"}, new WavelengthRange(450f, 495f))
                },
                {
                        new Color("red", 1, true, Temperature.WARM, new String[] {"maroon", "crimson"}, new WavelengthRange(620f, 740f)),
                        new Color("red", 1, true, Temperature.WARM, new String[] {"maroon", "crimson"}, new WavelengthRange(620f, 740f)),
                }
        };
    }


    @Test(dataProvider = "different", expectedExceptions = {AssertionError.class})
    public void testDifferent(Color actual, Color expected) throws Exception {
        this.testSame(actual, expected);
    }

    @DataProvider(name = "different")
    public Object[][] different() {
        return new Object[][] {
                {
                        new Color("red", 1, true, Temperature.WARM, new String[] {"maroon", "crimson"}, new WavelengthRange(620f, 740f)),
                        new Color("blue", 5, true, Temperature.COLD, new String[] {"aqua", "turquoise"}, new WavelengthRange(450f, 495f))
                },
                {
                        new Color("yellow", 3, true, Temperature.WARM, new String[] {"lemon"}, new WavelengthRange(570f, 590f)),
                        new Color("green", 4, false, Temperature.COLD, new String[] {"olive", "kelly"}, new WavelengthRange(520f, 570f))
                }
        };
    }
}