AssertJ exception handling (feat.assertThat isInstanceOf)-CodePudding

I have been on this problem for hours but couldn't get close to solution. Any help will be appreciated.

public static int enterTheAmount(){
    int final LOTTO_PRICE = 1000;
    int amount = Integer.parseInt(Console.readLine());
    if(amount%LOTTO_PRICE!=0) throw new IllegalArgumentException();

    return amount/LOTTO_PRICE;
}

Here, a user is going to enter a number, and if the number is not divisible by 1000, it throws an exception.

void validateTheEnteredAmount(){
    final String INVALID_NUMBER = "1234";
    InputStream in = new ByteArrayInputStream(INVALID_NUMBER.getBytes());
    System.setIn(in);
    assertThat(Application.enterTheAmount()).
            isInstanceOf(IllegalArgumentException.class);
}

And I want to know when invalid number is entered, illegalArgumentException is thrown. I used assertThat method & isInstanceOf methods to validate. but for some reason, the test keeps failing.. Anyone with clues, please help

i used inputStream to store the number into the scanner. On the console, it shows that illegalargumentexception is thrown, but the test fails..

CodePudding user response：

You should use assertThrows to check this.

assertThrows(IllegalArgumentException.class, () -> Application.enterTheAmount());

This will assert that the method throws an exception. If it doesn't, the test will be considered as failed.

CodePudding user response：

In the same situation I added a variable with Class type :

private Class exceptionClass;

And I will initialize it in a catch block as below:

public void updateBalance() {
        try {
            Account account = accountRepository.findById(id).get();
            account.setBalance(balance);
            accountRepository.save(account);
        } catch (Exception e) {
            exceptionClass = e.getClass();
        } 
    }

And I wrote a method for my class that will check the result like below:

boolean hasObjectOptimisticLockingFailure() {
    return this.exceptionClass == ObjectOptimisticLockingFailureException.class;
 }

Then in my test method I checked it with below assertion statement:

assertTrue(account1.hasObjectOptimisticLockingFailure() 
|| account2.hasObjectOptimisticLockingFailure());

I think you can do the same for your codes!!