[SalesForce] NullPointerException not occurring within try/catch

I'm writing a testMethod for a custom Exception class.

As part of the testMethod I want to deliberately throw another exception to become the inner cause of my custom exception.

E.g. 

public class CustomException extends Exception {

    public Id opportunityId {
        get;
        private set;
    }

    public CustomException(Id exceptionOpportuntiyId, string message, Exception innerException) {
        this.opportunityId = exceptionOpportuntiyId;
        this.setMessage(message);
        this.initCause(innerException);
    }
}

And the corresponding testMethod:

private static testMethod void customExceptionTest() {
    Id opportuntiyId = '006000000000000';
    try {
        Savepoint sp = Database.setSavepoint();
        try {

            integer foo = null;
            // Intentional NullPointerException
            foo = foo + 1;
            System.assert(false, 'Null Exception Expected');
        } catch (NullPointerException ex) {
            Database.rollback(sp);
            throw new CustomException(opportuntiyId, 'customExceptionTest', ex);
        }
        System.assert(false, 'CustomException Expected');
    } catch (CustomException saveEx) {
        System.assertEquals(opportuntiyId, saveEx.opportunityId);
        System.assertEquals('customExceptionTest', saveEx.getMessage());
    }
}

Oddly, the assertion in the inner try block is causing the test method to fail. The line foo = foo + 1 executed without throwing an exception!

This seemed odd, so I tried simplifying.

The following produces the expected NullPointerException when run as anonymous apex:

integer foo = null;
foo = foo + 1;

12:38:48:016 FATAL_ERROR System.NullPointerException: Attempt to de-reference a null object

The wrapping the same code in a try/catch block:

try {
    integer foo = null;
    foo = foo + 1;
    System.debug('foo: ' + foo);
} catch (NullPointerException ex) {
  System.debug('Exception');
}

12:42:28:013 USER_DEBUG [6]|DEBUG|foo: null

The expected NullPointerException didn't occur. Instead foo is null!

I've raised with support (Case #08416231), but is anyone else aware of this or can confirm it is occurring for them as well?

Ideally I'd like a known issue reference or existing case number.

Best Answer

I get the same and also agree it looks like an Apex runtime bug. Perhaps relating to scope, as moving the variable declaration and init out of the try scope works...

Integer foo = null;
try {
    foo = foo + 1;
    System.debug('foo: ' + foo);
} catch (NullPointerException ex) {
  System.debug('Exception');
}
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