递归 JUnit 测试

Question

因此，我正在尝试编写 3 个测试用例来查找我编写的递归方法是否正确。我对 JUnit 不太好，但这就是我到目前为止所得到的。

如何证明我的递归方法在 JUnit 中是正确的（如果是）？

这是我的班级：

public class Rhino {

    private String co; //The country in which this Rhino was born. Not null

    private Rhino parent; //null if this Rhino has no known parent

    /** Constructor : an instance born in country c with parent p.

     * Precondition : c is not null . */

    public Rhino(String c, Rhino p) {

        co = c;

        parent = p;

    }

    /** Return the number of Rhinos in this Rhino 's family that

    were

     * born in country c. This Rhino 's family consists of this

    Rhino , its

     * parent , its parent 's parent , its parent 's parent 's parent ,

    etc . */

    public int numCountry(String c) {

        if (parent == null){return co.equals(c) ? 1:0;}

        return(co.equals(c) ? 1:0) + parent.numCountry(c);

    }

}

到目前为止，这是我的 JUnit 测试：

import static org.junit.Assert.assertEquals;

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

class RhinoTest {

    @Test

    public void testCountry() {

        Rhino testCP = new Rhino("USA", null);

        assertEquals("USA", testCP.numCountry(""));

        assertNotEquals(testCP, null);

    }

}

Answer 1

试试这个基本测试，让你开始：public void testCountry() {    Rhino rA = new Rhino("USA", null);    Rhino rB = new Rhino("USA", rA);    Rhino rC = new Rhino("CANADA", rB);    Rhino rD = new Rhino("USA", rC);    int expectedResult = 3;    assertEquals(expectedResult, rD.numCountry("USA"));}