#vulnerable code 
                                @Test
    public void testGetChildProcesses() {
        // Get list of PIDS
        SystemInfo si = new SystemInfo();
        OperatingSystem os = si.getOperatingSystem();
        OSProcess[] processes = os.getProcesses(0, null);
        Map<Integer, Integer> childMap = new HashMap<>();
        // First iteration to set all 0's
        for (OSProcess p : processes) {
            childMap.put(p.getProcessID(), 0);
            childMap.put(p.getParentProcessID(), 0);
        }
        // Second iteration to count children
        for (OSProcess p : processes) {
            childMap.put(p.getParentProcessID(), childMap.get(p.getParentProcessID()) + 1);
        }
        // Find a PID with 0, 1, and N>1 children
        int zeroPid = -1;
        int onePid = -1;
        int nPid = -1;
        int nNum = 0;
        int mPid = -1;
        int mNum = 0;
        for (Integer i : childMap.keySet()) {
            if (zeroPid < 0 && childMap.get(i) == 0) {
                zeroPid = i;
            } else if (onePid < 0 && childMap.get(i) == 1) {
                onePid = i;
            } else if (nPid < 0 && childMap.get(i) > 1) {
                // nPid is probably PID=1 with all PIDs with no other parent
                nPid = i;
                nNum = childMap.get(i);
            } else if (mPid < 0 && childMap.get(i) > 1) {
                mPid = i;
                mNum = childMap.get(i);
            }
            if (zeroPid >= 0 && onePid >= 0 && nPid >= 0 && mPid >= 0) {
                break;
            }
        }
        if (zeroPid >= 0) {
            assertEquals(0, os.getChildProcesses(zeroPid, 0, null).length);
        }
        if (SystemInfo.getCurrentPlatformEnum() != PlatformEnum.SOLARIS) {
            // Due to race condition, a process may terminate before we count
            // its children. Play the odds.
            // At least one of these tests should work.
            if (onePid >= 0 && nPid >= 0 && mPid >= 0) {
                assertTrue(os.getChildProcesses(onePid, 0, null).length == 1
                        || os.getChildProcesses(nPid, 0, null).length == nNum
                        || os.getChildProcesses(mPid, 0, null).length == mNum);
            }
        }
    } 
                            #location 25 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testGetChildProcesses() {
        // Testing child processes is tricky because we don't really know a
        // priori what processes might have children, and if we do test the full
        // list vs. individual processes, we run into a race condition where
        // child processes can start or stop before we measure a second time. So
        // we can't really test for one-to-one correspondence of child process
        // lists.
        //
        // We can expect code logic failures to occur all/most of the time for
        // categories of processes, however, and allow occasional differences
        // due to race conditions. So we will test three categories of
        // processes: Those with 0 children, those with exactly 1 child process,
        // and those with multiple child processes. On the second poll, we
        // expect at least half of those categories to still be in the same
        // category.
        //
        SystemInfo si = new SystemInfo();
        OperatingSystem os = si.getOperatingSystem();
        OSProcess[] processes = os.getProcesses(0, null);
        Set<Integer> zeroChildSet = new HashSet<>();
        Set<Integer> oneChildSet = new HashSet<>();
        Set<Integer> manyChildSet = new HashSet<>();
        // Initialize all processes with no children
        for (OSProcess p : processes) {
            zeroChildSet.add(p.getProcessID());
        }
        // Move parents with 1 or more children to other set
        for (OSProcess p : processes) {
            if (zeroChildSet.contains(p.getParentProcessID())) {
                // Zero to One
                zeroChildSet.remove(p.getParentProcessID());
                oneChildSet.add(p.getParentProcessID());
            } else if (oneChildSet.contains(p.getParentProcessID())) {
                // One to many
                oneChildSet.remove(p.getParentProcessID());
                manyChildSet.add(p.getParentProcessID());
            }
        }
        // Now test that majority of each set is in same category
        int matched = 0;
        int total = 0;
        for (Integer i : zeroChildSet) {
            if (os.getChildProcesses(i, 0, null).length == 0) {
                matched++;
            }
            // Quit if enough to test
            if (++total > 9) {
                break;
            }
        }
        if (total > 4) {
            assertTrue("Most processes with no children should not suddenly have them.", matched > total / 2);
        }
        matched = 0;
        total = 0;
        for (Integer i : oneChildSet) {
            if (os.getChildProcesses(i, 0, null).length == 1) {
                matched++;
            }
            // Quit if enough to test
            if (++total > 9) {
                break;
            }
        }
        if (total > 4) {
            assertTrue("Most processes with one child should not suddenly have zero or more than one.",
                    matched > total / 2);
        }
        matched = 0;
        total = 0;
        for (Integer i : manyChildSet) {
            if (os.getChildProcesses(i, 0, null).length > 1) {
                matched++;
            }
            // Quit if enough to test
            if (++total > 9) {
                break;
            }
        }
        if (total > 4) {
            assertTrue("Most processes with more than one child should not suddenly have one or less.",
                    matched > total / 2);
        }
    }