如何在junit测试中测试比较器

Question

我需要测试这种方法 - compare().你能得到建议吗？我能做得更好(所有部分if,else-if,else).

public class AbsFigure {

class AreaCompare implements Comparator<FigureGeneral> {

    @Override
    public int compare(FigureGeneral oneFigure, FigureGeneral twoFigure) {
        double firstValue = oneFigure.area();
        double secondValue = twoFigure.area();
        int result = 0;

        if (firstValue > secondValue)
            result = 1;
        else if (firstValue < secondValue)
            result = -1;
        else
            result = 0;

        return result;
    }
}

在这个推荐之后 - 我们有下一张图片(非常感谢你们!):

public AreaCompare areaCompare = new AreaCompare();

@Test
public void testEqual() {
    FigureGeneral oneFigure = new Rectangle(2.0, 2.0, "triangle");
    FigureGeneral twoFigure = new Rectangle(2.0, 2.0, "rectangle");
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be equal", result == 0);
}

@Test
public void testGreaterThan() {
    FigureGeneral oneFigure = new Triangle(2.0, 2.0, "triangle");
    FigureGeneral twoFigure = new Rectangle(1.0, 1.0, "rectangle");
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be greater than", result >= 1);
}

@Test
public void testLessThan() {
    FigureGeneral oneFigure = new Rectangle(1.0, 1.0, "rectangle");
    FigureGeneral twoFigure = new Triangle(2.0, 2.0, "triangle");
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be less than", result <= -1);

现在一切正常.

Answer 1

只需实例化你的比较器类并传入对象:

public class Test extends TestCase {
    class AreaCompare implements Comparator<FigureGeneral> {

        @Override
        public int compare(FigureGeneral oneFigure, FigureGeneral twoFigure) {
            double firstValue = oneFigure.area();
            double secondValue = twoFigure.area();
            int result = 0;

            if (firstValue > secondValue) {
                result = 1;
            } else if (firstValue < secondValue) {
                result = -1;
            } else {
                result = 0;
            }

            return result;
        }
    }

    private final AreaCompare areaCompare = new AreaCompare();

    @Test
    public void testEqual() {
        FigureGeneral oneFigure = new FigureGeneral();
        FigureGeneral twoFigure = new FigureGeneral();
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be equal", result == 0);
    }

    @Test
    public void testGreaterThan() {
        FigureGeneral oneFigure = new FigureGeneral();
        FigureGeneral twoFigure = new FigureGeneral();
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be greater than", result >= 1);
    }

    @Test
    public void testLessThan() {
        FigureGeneral oneFigure = new FigureGeneral();
        FigureGeneral twoFigure = new FigureGeneral();
        int result = areaCompare.compare(oneFigure, twoFigure);
        assertTrue("expected to be less than", result <= -1);
    }
}