java - Junit测试扫描仪输入问题

Question

我目前正在尝试对 Uni 作业的游戏进行 Junit 测试。下面是我正在尝试测试的方法的示例。

public static int choosePlayers(int num) {
    while (validPlayerNumber == false) {
        try {
            System.out.print("Please enter Number of players (2-4)\n> ");
            num = in.nextInt();
            switch (num) {
            case 2:
                validPlayerNumber = true;
                numberPlayers = num;
                System.out.println(numberPlayers + " players selected");
                break;
            case 3:
                validPlayerNumber = true;
                numberPlayers = num;
                System.out.println(numberPlayers + " players selected");
                break;
            case 4:
                validPlayerNumber = true;
                numberPlayers = num;
                System.out.println(numberPlayers + " players selected");
                break;
            default:
                throw new IllegalArgumentException("Sorry, that is not a valid selection.");
                // System.out.println("Sorry, that is not a valid selection.");
            }
        } catch (InputMismatchException ex) {
            // log the exception
            System.out.println("Problem with input : " + ex.toString());
            continue;
        }
    }
    return numberPlayers;
}

我正在使用以下测试类来测试它:

/**
 * @throws java.lang.Exception
 */
@Before

public void setUp() throws Exception {
    num1 =1;
    num2= 2;
    num4 = 4;
    num3 = 3;
    num5 = 5;
    game= new Game();
}

@Test
public void testchoosePlayers2() {

 System.out.println("Testing choosingPlayers 2");
Scanner scanner = new Scanner (System.in);
 int expected = scanner.nextInt();
  int actual = game.choosePlayers(num2);
 assertEquals(expected, actual);
 System.out.println("Test finsihed");
}


@Test
public void testchoosePlayers3() {
    System.out.println("Testing choosingPlayers 3");
    Scanner scanner = new Scanner (System.in);
    int expected = scanner.nextInt();
    int actual = game.choosePlayers(num3);
     assertEquals(expected, actual);
     System.out.println("Test finsihed");

}


@Test
public void testchoosePlayers4() {
    System.out.println("Testing choosingPlayers 4");
    Scanner scanner = new Scanner (System.in);
    int expected = scanner.nextInt();
    int actual = game.choosePlayers(num4);
     assertEquals(expected, actual);
     System.out.println("Test finsihed");

}

每次我尝试运行此测试时，只会运行第一个测试，并且不会重新提示扫描仪进行后续的 2 次测试。有什么办法可以解决此问题吗？我非常感谢有关此问题的任何建议或更好/更有效的方法来测试上述方法。

Answer 1

您的目的是测试该方法使用提供的输入参数返回正确的值。如果扫描的值不正确，测试将失败。因此，不必扫描期望值，只需将期望值放入断言中即可。此外，您不需要在这里进行单独的测试，因为您测试的是相同的功能。

要模拟输入，您需要将 System.in 替换为您自己的输入流。请参阅JUnit: How to simulate System.in testing?了解详情。

    private final InputStream systemIn = System.in;
    private ByteArrayInputStream testIn;

    @After
    public void resetSystemIn() {
        System.setIn(systemIn);
    }

    private void inputData(String data) {
        testIn = new ByteArrayInputStream(data.getBytes());
        System.setIn(testIn);
    }

    @Test
    public void testchoosePlayers() {
        System.out.println("Testing choosingPlayers 2");
        inputData("2");
        int actual = game.choosePlayers(num2);
        assertEquals(num2, actual);
        System.out.println("Testing choosingPlayers 3");
        inputData("3");
        actual = game.choosePlayers(num3);
        assertEquals(num3, actual);
        System.out.println("Testing choosingPlayers 4");
        inputData("4");
        actual = game.choosePlayers(num4);
        assertEquals(num4, actual);
        System.out.println("Test finsihed");
    }