Baseline exception in selenium Java

[shunguoy]

user reported from Slack: https://ibm-studios.slack.com/archives/C036P1CTN/p1729821107094459

I'm using the selenium java accessibility checker. I was trying to use the baselines and I'm seeing a null pointer exception. My baseline has 53 items but my actual has 60 and it's blowing up on this line with
java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 53
at com.ibm.able.equalaccess.report.BaselineManager.diff(BaselineManager.java:273)
at com.ibm.able.equalaccess.report.BaselineManager.diffResultsWithExpected(BaselineManager.java:208)
at com.ibm.able.equalaccess.report.BaselineManager.assertCompliance(BaselineManager.java:135)
at com.ibm.able.equalaccess.AccessibilityChecker.assertCompliance(AccessibilityChecker.java:93)
Screenshot 2024-09-16 at 8.22.43 PM.png

Screenshot 2024-09-16 at 8.22.43 PM.png

[amyreit]

I could be using the calls incorrectly but if so, can you please tell me how to compare the current report to my baseline. I was trying to do this thinking that if they didn't match, the assertCompliance call would return BASELINE_MISMATCH but stepping through the code, that's never going to work if they aren't the same size. In my case, the baseline file had 25 elements but the actual file had 35:

        matchBaseline = AccessibilityChecker.assertCompliance(report);
             if (matchBaseline==eAssertResult.BASELINE_MISMATCH) {
                   // handle a failure here
            }

I also tried this way :

ACReport baselineRpt = AccessibilityChecker.getBaseline(pageForComplianceCheck);
           DiffResult[] diffs = AccessibilityChecker.diffResultsWithExpected(report, baselineRpt);

but hits same line of code eventually and fails the same way.

Here's the code in BaselineManager.java:273. It fails here because the for loop is going from the expected length of 25 to the actual length of 35 and so right away expectedRs[25] is out of index since my expected file only has 0-24 elements.

for (int idx=expectedRs.length; idx < actualRs.length; ++idx) {
           retVal.add(new DiffResult("A", idx, gson.toJson(expectedRs[idx]), null));  
       }