如何为提示用户输入int的方法编写Junit测试

Question

• 超出此范围
  • 该方法将不断询问，直到输入正确的数字。列为
  • arrays starting at 0 and returned
  • @param turn Player which ever players turn it is, is asked for a column
  • @return int the column is returned after lowered by one */

    
    System.out.println("\n\n" + turn.getTag() + " please enter the column number, 1-7,  \n"
            + "where you would like to drop your game piece. ");
    boolean colCorrect = false;
    int column = -1;
    while (!colCorrect){
        if(Connect4TextConsole.in.hasNextInt()){
            column = Connect4TextConsole.in.nextInt();
            colCorrect = true;}
        else{ System.out.println("Please enter a number 1 through 7.");
            Connect4TextConsole.in.next();}}
    while(column < 1 || column > 7) {
        System.out.println("Please enter a number 1 through 7.");
        column = Connect4TextConsole.in.nextInt();
    }
    return column - 1; // subtract one to account for array starting at zero
    }``` 
    

Answer 1

在测试代码时，您不需要测试Java的API:您可以假设scanner工作（例如）。

最灵活的实现方法可能是将扫描程序注入到处理用户输入的类中，然后在测试代码中模拟该扫描程序：

class InputHandler {
    private final Scanner input;

    public InputHandler(Scanner input) {
        this.input = input;
    }

    public void nextChoice() {
        int choice = input.nextInt();
        ...
    }
}

那么您的生产代码将如下所示：

InputHandler inputHandler = new InputHandler(new Scanner(System.in));

@Test void option2() {
    Scanner input = mock(Scanner.class);
    when(input.nextInt()).thenReturn(2);
    InputHandler testHandler = new InputHandler(input);
    ...
}

@Test void illegalInput() {
    Scanner input = mock(Scanner.class);
    when(input.nextInt()).thenThrow(InputMismatchException.class);
    InputHandler testHandler = new InputHandler(input);
    ...
}

@Test
void testChoicePrompt() {
    Scanner input = mock(Scanner.class);
    PrintStream output = mock(PrintStream.class);
    InputHandler inputHandler = new InputHandler(input, output);
    inputHandler.nextChoice();
    verify(output).println("Enter choice:");
}