Exercise using exception handling in Bank program

• Modify your Checking class so that if the amount to be withdrawn exceeds the balance by more than overdraftMaximum, it throws an exception: InsufficientFundsException.
  • throw new InsufficientFundsException("...");
  • // Put the above statement at the appropriate place in your code, i.e. when you determine that there was an attempt to withdraw too much money.
  • // Replace the String parameter with something appropriate, e.g. Trying to withdraw too much: $... from ...
• You will need a new class named InsufficientFundsException (like Chapter 4 examples MyRuntimeException or MyException, depending on whether you want a Runtime exception or a Checked exception), e.g. public class InsufficientFundsException extends RuntimeException // Change MyRuntimeException to InsufficientFundsException in the given class MyRuntimeException. You are creating/defining a new (user-defined) exception. Once you get this to work, you may (optionally) see what happens if your new exception type extends Exception rather than RuntimeException.
• Test using JUnit.

  		@Test
  		public void testOverwithdraw() {
  			// Create a checking account.
  			Checking acc = new Checking(...);
  
  			try {
  				// Withdraw an amount that should cause an exception of type InsufficientFundsException...
  				acc.withdraw( new Money(200, 0) );
  
  				// If we reach this point in the code, that means the exception was not thrown as expected, so this test case fails.
  				fail(); 
  			}
  			catch (InsufficientFundsException ife) {
  				System.out.println("InsufficientFunds Exception on testOverwithdraw");
  				ife.printStackTrace();
  			}
  			
  		}
  		

  An alternative way to test that an InsufficientFundsException was thrown appropriately:

      @Test
      public void whenExceptionThrown_thenAssertionSucceeds() {
          Exception exception = assertThrows(InsufficientFundsException.class, () -> {   
                // Create a checking account.
  	      Checking acc = new Checking(...);
  
  	      // Withdraw an amount that should cause an exception of type InsufficientFundsException...
  	      acc.withdraw( new Money(200, 0) );
          });
          
          String expectedMessage = "Trying to withdraw too much";
          String actualMessage = exception.getMessage();
      
          assertTrue(actualMessage.contains(expectedMessage));
      }