VAVectorTest.java

package me.moodcat.database.embeddables;

import static org.junit.Assert.assertEquals;

import java.util.ArrayList;
import java.util.List;

import junitx.extensions.EqualsHashCodeTestCase;

import org.junit.Test;
import org.junit.experimental.runners.Enclosed;
import org.junit.runner.RunWith;

/**
 * Test to make sure {@link VAVector vectors} are elementary.
 *
 * @author JeremybellEU
 */
@RunWith(Enclosed.class)
public class VAVectorTest {

	public static class VAVectorEqualsTest extends EqualsHashCodeTestCase {

		public VAVectorEqualsTest(final String name) {
			super(name);
		}

		@Override
		protected Object createInstance() throws Exception {
			return new VAVector(0.5, 0.5);
		}

		@Override
		protected Object createNotEqualInstance() throws Exception {
			return new VAVector(0.5, 1.0);
		}
	}

	public static class VAVectorCalculationsTest {

		@Test
		public void additionAndSubstractionReturnSameVector() {
			final VAVector one = new VAVector(0.5, 0.5);
			final VAVector other = new VAVector(0.25, 0.25);

			assertEquals(one, one.add(other).subtract(other));
		}

		@Test
		public void multiplicationTwoAndSubstractionReturnSameVector() {
			final VAVector one = new VAVector(0.5, 0.5);
			final double scalar = 2;

			assertEquals(one, one.multiply(scalar).subtract(one));
		}

		@Test
		public void multiplicationTwoDistanceIsOne() {
			final VAVector one = new VAVector(0.5, 0.0);
			final double scalar = 2;

			assertEquals(one.length(), one.distance(one.multiply(scalar)), 1E-5);
			assertEquals(one.length(),
					VAVector.distance(one, one.multiply(scalar)), 1E-5);
		}

		@Test
		public void averageOfList() {
			final VAVector one = new VAVector(0.5, 0.5);
			final VAVector second = new VAVector(1.0, 1.0);
			final VAVector otherOne = new VAVector(-0.5, -0.5);
			final VAVector otherSecond = new VAVector(-1.0, -1.0);

			final List<VAVector> vectors = new ArrayList<VAVector>();
			vectors.add(one);
			vectors.add(second);
			vectors.add(otherOne);
			vectors.add(otherSecond);

			assertEquals(new VAVector(0.0, 0.0), VAVector.average(vectors));
		}

		@Test
		public void averageOfEmptyListIsZeroVector() {
			final VAVector zero = new VAVector(0.0, 0.0);

			final List<VAVector> vectors = new ArrayList<VAVector>();

			assertEquals(zero, VAVector.average(vectors));
		}
	}

}