java - 如何将 JUnit 测试用例的多个输入模拟到我的程序中？

Question

我编写了一个如下所示的程序:

import java.util.Scanner;
import java.util.ArrayList;

public class Triangles {

    public static void main(String[] args) {

        Scanner user_input = new Scanner(System.in);

        ArrayList<String> triangleLengths = new ArrayList<String>();

        for (int i=0; i < 3; i++) {

            System.out.print("Triangle length #" + i + ": ");
            triangleLengths.add(i,user_input.next());   
        }

        if (triangleLengths.get(0) == triangleLengths.get(1) && triangleLengths.get(1) == triangleLengths.get(2)) {

            System.out.println("This triangle is an equilateral triangle");

        } else if (triangleLengths.get(0) == triangleLengths.get(1) || triangleLengths.get(0) == triangleLengths.get(2) || triangleLengths.get(1) == triangleLengths.get(2)) {

            System.out.println("This triangle is an isosceles triangle");

        } else if (triangleLengths.get(0) != triangleLengths.get(1) && triangleLengths.get(1) != triangleLengths.get(2)) {

            System.out.println("This triangle is a scalene triangle");

        } else {

            System.out.println("The input does not make a triangle!");

        }


    }

}

我的任务是编写一个 JUnit 测试用例，本质上是尝试通过使用各种输入进行测试来“破坏”我的程序。作为一个完全的 Java 新手，我一生都无法弄清楚如何做到这一点 - 有人能给我指出正确的方向吗？

Answer 1

所以我提出了如何解决这个问题的建议。

您希望能够自动使用不同的参数进行测试，而无需手动输入，因此我隔离了三角形部分，如下所示。

编辑:我稍微重新编写了代码

正常运行类src/main.java

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

public class Main {

    public static void main(String[] args) {
        Scanner user_input = new Scanner(System.in);
        List<String> triangleLengths = new ArrayList<>();

        for (int i = 0; i < 3; i++) {
            System.out.print("Triangle length #" + i + ": ");
            triangleLengths.add(i, user_input.next());
        }

        // Result output will be here
        Triangle subject = new Triangle(triangleLengths);
        if (subject.getTriangleType() == Triangle.Type.INVALID) {
            System.out.println("Triangle is invalid");
        } else {
            System.out.println("Triangle is: " + subject.getTriangleType());
        }
    }
}

JUnit 类test/TrianglesTest.java

import org.junit.Test;

import java.util.Arrays;
import java.util.List;

import static org.junit.Assert.assertEquals;

public class TrianglesTest {

    /**
     * Testing with String inputs (what you'd enter manually)
     */
    @Test
    public void testWithStrings() {
        List<String> triangleLengths = Arrays.asList("len1", "len2", "len3");

        Triangle subject = new Triangle(triangleLengths);
        // Example of checking if expected type
        assertEquals(Triangle.Type.ISOSCELES, subject.getTriangleType());
    }

    /**
     * Testing with numbers as what I'd expect the triangle to be made of
     *
     * Here you test with a triangle object
     *
     * Haven't tested what the 3 types is sorry :O
     */
    @Test
    public void testWithNumbersAsObject() {
        Triangle subject = new Triangle(4, 5.32, 7);
        assertEquals(Triangle.Type.SCALENE, subject);
    }

    /**
     * This piece you check the static method but have no object
     */
    @Test
    public void testWithNumbersStaticMethod() {
        assertEquals(Triangle.Type.ISOSCELES, Triangle.getTriangleType(3.4d, 4d, 1.111d));
    }
}

最后是您想要测试的实际代码src/Triangles.java

import java.util.List;

/**
 * I created so you can both have an object of the triangle or make the check purely static
 * maybe you need an object type for later?
 */
public class Triangle {

    final double side0;
    final double side1;
    final double side2;

    public Triangle(List<String> triangleLengths) {
        this(Double.parseDouble(triangleLengths.get(0)),
                Double.parseDouble(triangleLengths.get(1)),
                Double.parseDouble(triangleLengths.get(2)));
    }

    public Triangle(double side0, double side1, double side2) {
        this.side0 = side0;
        this.side1 = side1;
        this.side2 = side2;
    }

    public Triangle.Type getTriangleType() {
        return Triangle.getTriangleType(side0, side1, side2);
    }

    public static Triangle.Type getTriangleType(double side0, double side1, double side2) {
        if (isEquilateral(side0, side1, side2)) {
            return Type.EQUILATERAL;
        } else if (isIsosceles(side0, side1, side2)) {
            return Type.ISOSCELES;
        } else if (isScalene(side0, side1, side2)) {
            return Type.SCALENE;
        } else {
            return Type.INVALID;
        }
    }

    private static boolean isScalene(double side0, double side1, double side2) {
        return side0 != side1 && side1 != side2;
    }

    private static boolean isIsosceles(double side0, double side1, double side2) {
        return side0 == side1 || side0 == side2 || side1 == side2;
    }

    private static boolean isEquilateral(double side0, double side1, double side2) {
        return side0 == side1 && side1 == side2;
    }

    public enum Type {
        EQUILATERAL,
        ISOSCELES,
        SCALENE,
        INVALID
    }
}

希望这有帮助。

请注意，我从 Triangles 类返回答案，而不是立即写出来。并且只有在手动运行时我才从 main 方法中将其写出来。