Bug 210130

Summary:	False positive "Potential null pointer access" warning after TestCase.fail
Product:	[Eclipse Project] JDT	Reporter:	Nick Radov <nradov>
Component:	Core	Assignee:	Maxime Daniel <maxime_daniel>
Status:	VERIFIED WONTFIX	QA Contact:
Severity:	normal
Priority:	P3	CC:	david_audel, Olivier_Thomann
Version:	3.3.1
Target Milestone:	3.4 M4
Hardware:	PC
OS:	Windows XP
Whiteboard:

Description Nick Radov

2007-11-16 13:58:25 EST

Build ID: M20071023-1652

Try the following code.


import java.util.Random;

import junit.framework.TestCase;

public class Test extends TestCase {

    private boolean[] getArray() {
	if (new Random().nextFloat() < 0.5) {
	    return null;
	} else {
	    return new boolean[] { true };
	}
    }

    public void testNull() {
	final boolean[] array = getArray();
	if (array == null) {
	    fail("null");
	}
	for (int i = 0; i < array.length; i++) {
	    System.out.println(array[i]);
	}
    }
}

That code triggers a "Potential null pointer access" on the array.length statement. However, if array == null then the method will have already terminated by calling TestCase.fail(String).
This is similar to Bug 132875 but not exactly the same.

Comment 1 Maxime Daniel

2007-11-17 05:31:23 EST

Thanks for your suggestion. I am afraid our current plans won't allow us to pursue it though. As you noticed, this is much like bug 132875 - a P5 as of today, and would call for an even more specific pattern, tied to JUnit, or for a cross methods analysis to discover that fail will throw an unchecked exception in all cases.

Note that a few workarounds can help you get rid of the unwanted warning, such as:
    public void testNull() {
        final boolean[] array = getArray();
        if (array == null) {
            fail("null");
            return;
        }
        for (int i = 0; i < array.length; i++) {
            System.out.println(array[i]);
        }
    }
which makes explicit to us that we exit from within the if block.

Closing as WONTFIX.

Comment 2 David Audel

2007-12-11 07:04:21 EST

Verified for 3.4M4.