Fix unclear test case failure messages with detailed expected vs actual output comparison

[Copilot]

Problem

When test cases failed, users only saw generic messages like "test case failed" without any indication of what the expected output was versus what their code actually produced. This made debugging extremely difficult as users had no way to understand why their solution was incorrect.

Before this fix:

❌😭 Test Case 1: Failed! 😭 
Error: Test case 1 failed.
Actual Output: N/A

Solution

Enhanced the error handling to provide detailed expected vs actual output comparison when test cases fail.

After this fix:

❌😭 Test Case 1: Failed! 😭
❌ Test case 1 failed.
Expected Output: "[1,2,3]"
Actual Output: "[1,2,4]"

Changes Made

1. Modified compareOutputs() function in executeCode.ts:

   • Instead of rejecting with a simple "Test case X failed" message
   • Now includes detailed comparison showing both expected and actual outputs
   • Maintains the same console logging while improving the error message passed to the UI

2. Enhanced error handling in extension.ts:

   • Detects when error messages contain detailed comparison information
   • Displays the full expected vs actual comparison to users
   • Falls back to previous behavior for other error types (compilation, runtime errors)

3. Updated documentation:

   • Removed the known issue about unclear failure messages from README
   • Added feature highlighting the improved error messaging

Benefits

• Better debugging experience: Users can immediately see what their code produced vs what was expected
• Faster problem resolution: No need to manually check output files or guess what went wrong
• Backward compatible: Maintains existing behavior for non-comparison errors
• Clear visual distinction: Easy to spot differences between expected and actual results

Testing

Created comprehensive tests demonstrating the improvement works correctly for various data types (arrays, strings, numbers) while maintaining compatibility with successful test cases.

Fixes #2.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• googlechromelabs.github.io
  • Triggering command: node install.mjs (dns block)
• https://storage.googleapis.com/chrome-for-testing-public/131.0.6778.204/linux64/chrome-headless-shell-linux64.zip
  • Triggering command: node install.mjs (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

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