BruteCollinearPointsTest.java

/* *****************************************************************************
 *  Name:
 *  Date:
 *  Description:
 **************************************************************************** */

import org.junit.Assert;
import org.junit.Test;

import static junit.framework.TestCase.assertEquals;
import static junit.framework.TestCase.assertNotNull;

public class BruteCollinearPointsTest {
    @Test
    public void ctor_whenPointsArrayNull_throwsIllegalArgumentException() {
        // Arrange
        Point[] points = null;
        IllegalArgumentException illegalArgumentException = null;

        // Act
        try {
            new BruteCollinearPoints(points);
        } catch (IllegalArgumentException e) {
            illegalArgumentException = e;
        }

        // Assert
        assertNotNull(illegalArgumentException);
    }

    /**
     * This test is very precise to make sure double equality issues are taken care
     */
    @Test
    public void segments_whenThereAreNoColinearPoints_returnsNoSegments() {
        // Arrange
        Point[] points = new Point[] { new Point(10000, 10000), new Point(20000, 20000), new Point(30000, 30000), new Point(40000, 40001)};
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        LineSegment[] segments = bruteCollinearPoints.segments();

        // Assert
        Assert.assertEquals(0, segments.length);
    }


    @Test
    public void ctor_whenPointsArrayContainsNullElement_throwsIllegalArgumentException() {
        // Arrange
        Point[] points = new Point[] { new Point(1,1), null, new Point(3, 3), new Point(4, 4)};
        IllegalArgumentException illegalArgumentException = null;

        // Act
        try {
            new BruteCollinearPoints(points);
        } catch (IllegalArgumentException e) {
            illegalArgumentException = e;
        }

        // Assert
        assertNotNull(illegalArgumentException);
    }

    @Test
    public void ctor_whenAnyPointsArrayContainsDuplicates_throwsIllegalArgumentException() {
        // Arrange
        Point[] points = new Point[] { new Point(1,1), new Point(2, 2), new Point(3, 3), new Point(3, 3)};
        IllegalArgumentException illegalArgumentException = null;

        // Act
        try {
            new BruteCollinearPoints(points);
        } catch (IllegalArgumentException e) {
            illegalArgumentException = e;
        }

        // Assert
        assertNotNull(illegalArgumentException);
    }

    @Test
    public void numberOfSegments_whenFourOfFourPointsOnTheSameLine_returnsOneSegment() {
        // Arrange
        Point[] points = new Point[] { new Point(1, 1), new Point(2, 2), new Point(3, 3), new Point(4, 4)};
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        int numberOfSegments = bruteCollinearPoints.numberOfSegments();

        // Assert
        assertEquals(1, numberOfSegments);
    }

    @Test
    public void numberOfSegments_whenFourOfFivePointsOnTheSameLine_returnsOneSegment() {
        // Arrange
        Point[] points = new Point[] { new Point(1, 2), new Point(1, 1), new Point(2, 2), new Point(3, 3), new Point(4, 4)};
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        int numberOfSegments = bruteCollinearPoints.numberOfSegments();

        // Assert
        assertEquals(1, numberOfSegments);
    }


    @Test
    public void segments_whenFirstOutOfFivePointsIsNotOnTheLine() {
        // Arrange
        Point[] points = new Point[] { new Point(2, 1), new Point(2, 2), new Point(3, 3), new Point(4, 4), new Point(5, 5)};
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        LineSegment segment = bruteCollinearPoints.segments()[0];

        // Assert
        assertEquals("(2, 2) -> (5, 5)", segment.toString());
    }

    @Test
    public void segments_whenThereAreTwoColinearLines() {
        Point[] points = new Point[] {
                new Point(10, 0),
                new Point(0, 10),
                new Point(3, 7),
                new Point(7, 3),
                new Point(20, 21),
                new Point(3, 4),
                new Point(14, 15),
                new Point(6, 7) };
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        LineSegment[] segments = bruteCollinearPoints.segments();

        // Assert
        assertEquals(2, segments.length);
        assertEquals("(10, 0) -> (0, 10)", segments[0].toString());
        assertEquals("(3, 4) -> (20, 21)", segments[1].toString());
    }

    @Test
    public void segments_whenThereIsVerticalSegment() {
        Point[] points = new Point[] {
                new Point(1, 1),
                new Point(1, 2),
                new Point(1, 3),
                new Point(1, 4)};
        BruteCollinearPoints bruteCollinearPoints = new BruteCollinearPoints(points);

        // Act
        LineSegment[] segments = bruteCollinearPoints.segments();

        // Assert
        assertEquals(1, segments.length);
        assertEquals("(1, 1) -> (1, 4)", segments[0].toString());
    }
}