PointTest.java

import org.junit.Test;

import static junit.framework.TestCase.assertEquals;

public class PointTest {
    @Test
    public void compareTo_whenAandBareSame_shouldReturn0() {
        // Arrange
        Point pointA = new Point(0, 0);
        Point pointB = new Point(0, 0);

        // Act
        int result = pointA.compareTo(pointB);

        // Assert
        assertEquals(0, result);
    }

    @Test
    public void compareTo_whenAhigherThanB_shouldReturn1() {
        // Arrange
        Point pointA = new Point(1, 10);
        Point pointB = new Point(5, 5);

        // Act
        int result = pointA.compareTo(pointB);

        // Assert
        assertEquals(1, result);
    }

    @Test
    public void compareTo_whenAlowerThanB_shouldReturnMinus1() {
        // Arrange
        Point pointA = new Point(5, 5);
        Point pointB = new Point(1, 10);

        // Act
        int result = pointA.compareTo(pointB);

        // Assert
        assertEquals(-1, result);
    }

    @Test
    public void compareTo_whenAisToTheLeftFromB_shouldReturnMinues1() {
        // Arrange
        Point pointA = new Point(0, 1);
        Point pointB = new Point(1, 1);

        // Act
        int result = pointA.compareTo(pointB);

        // Assert
        assertEquals(-1, result);
    }

    @Test
    public void compareTo_whenAisToTheRightFromB_shouldReturn1() {
        // Arrange
        Point pointA = new Point(1, 1);
        Point pointB = new Point(0, 1);

        // Act
        int result = pointA.compareTo(pointB);

        // Assert
        assertEquals(1, result);
    }

    @Test
    public void slopeTo_whenDegenerateLineSegment_shouldReturnNegativeInfinity() {
        // Arrange
        Point pointA = new Point(1, 1);
        Point pointB = new Point(1, 1);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(Double.NEGATIVE_INFINITY, result);
    }


    /**
     * 2
     * 2
     * 1 A B
     * 0 1 2 2
     */
    @Test
    public void slopeTo_whenHorizontalLeftToRight_shouldReturnPositiveZero() {
        Point pointA = new Point(1, 1);
        Point pointB = new Point(2, 1);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(0.0, result);
    }

    /**
     * 2
     * 2
     * 1 B A
     * 0 1 2 2
     */
    @Test
    public void slopeTo_whenHorizontalRightToLeft_shouldReturnPositiveZero() {
        Point pointA = new Point(2, 1);
        Point pointB = new Point(1, 1);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(0.0, result);
    }

    /**
     *     B
     *
     *  A
     *
     */
    @Test
    public void slope_whenPointcloserToXandY_shouldBePositive() {
        Point pointA = new Point(1, 1);
        Point pointB = new Point(3, 3);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(1.0, result);
    }

    /**
     * 8   A
     * 7
     * 6
     * 5
     * 4
     * 3
     * 2                   B
     * 1
     * 0 1 2 3 4 5 6 7 8 9 10
     */
    @Test
    public void slope_whenDeclinedToTheRight_shouldBeNegative() {
        Point pointA = new Point(2, 8);
        Point pointB = new Point(10, 2);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(-0.75, result);
    }

    @Test
    public void slopeTo_whenVerticalLine_shouldReturnPositiveZero() {
        Point pointA = new Point(1, 1);
        Point pointB = new Point(1, 10);

        // Act
        double result = pointA.slopeTo(pointB);

        // Assert
        assertEquals(Double.POSITIVE_INFINITY, result);
    }

    @Test
    public void slopeOrder_whenComparingToTheSamePoint_returnsZero() {
        // Arrange
        Point basePoint = new Point(1, 1);
        Point pointA = new Point(10, 10);
        Point pointB = new Point(10, 10);

        // Act
        int result = basePoint.slopeOrder().compare(pointA, pointB);

        // Assert
        assertEquals(0, result);
    }

    @Test
    public void slopeOrder_whenFirstSlopeSmaller_returnsMinus1() {
        // Arrange
        Point basePoint = new Point(1, 1);
        Point pointA = new Point(2, 2);
        Point pointB = new Point(3, 4);

        // Act
        int result = basePoint.slopeOrder().compare(pointA, pointB);

        // Assert
        assertEquals(-1, result);
    }

    @Test
    public void slopeOrder_whenFirstSlopeLarger_returnsPlus1() {
        // Arrange
        Point basePoint = new Point(1, 1);
        Point pointA = new Point(2, 4);
        Point pointB = new Point(2, 2);

        // Act
        int result = basePoint.slopeOrder().compare(pointA, pointB);

        // Assert
        assertEquals(1, result);
    }
}