因此，我正在嘗試編寫 3 個(gè)測(cè)試用例來查找我編寫的遞歸方法是否正確。我對(duì) JUnit 不太好，但這就是我到目前為止所得到的。如何證明我的遞歸方法在 JUnit 中是正確的（如果是）？這是我的班級(jí)：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);    }}到目前為止，這是我的 JUnit 測(cè)試：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);    }}