Fixing MDL-83541 Failing Unit Tests For Wiris Plugin In Moodle

by Axel Sørensen 63 views

Hey everyone!

I've run into some snags while running PHP unit tests with the Wiris plugin installed, and I wanted to share the fix for a specific failing test. This article dives into the issue, how to recreate it, the error output, and most importantly, the solution.

The failing unit test is mod/quiz/tests/backup/repeated_restore_test.php. This issue is tied to MDL-83541, and you can find more details about fixing it in the Moodle developer documentation on qtype restore.

Let's get into the details!

Understanding the Issue

To really grasp this fix, let's break down what's happening. This issue revolves around how Moodle handles the restoration of quizzes, especially when dealing with questions that have been duplicated or edited. The repeated_restore_test.php unit test is designed to specifically test these scenarios. The failing tests indicate that during the restoration process, the system is not correctly mapping or updating question IDs, leading to mismatches and assertion failures.

When a quiz is backed up and restored, Moodle needs to ensure that all the relationships between the quiz, its questions, and any associated data (like answers, hints, etc.) are maintained. This becomes tricky when the same quiz or questions are restored multiple times or when questions have been edited between backups and restores. The system needs to avoid creating duplicate entries and ensure that any references to old IDs are updated to the new ones.

The core problem lies in the way the Wiris plugin interacts with this restoration process, particularly in how it handles the unique identifiers for its question types. The multichoicewiris question type, which is central to this issue, uses its own internal mechanisms for managing question data. During a restore, these internal mechanisms might not be correctly synchronized with Moodle's restoration process, leading to the observed ID mismatches.

The error messages we're seeing – "Failed asserting that two strings are equal" and "Failed asserting that ... matches expected" – are clear indicators that the question IDs being restored are not matching the expected IDs. This could be due to the system creating new questions instead of updating existing ones, or incorrectly referencing old IDs.

To summarize, the issue stems from a misalignment between the Wiris plugin's internal question management and Moodle's quiz restoration process, particularly when dealing with duplicated or edited questions. This misalignment results in incorrect question ID mappings, causing the unit tests to fail.

Environment

Here's the environment where I encountered this issue:

PHP 8.1
Moodle 4.5
PgSQL 16.0
Branch: main

How to Recreate the Issue

Want to see this in action? Here's how you can recreate the issue:

  1. Deploy a local Moodle 4.5 instance: Make sure you have a Moodle 4.5 environment set up locally.

  2. Install the Wiris plugin: Install the Wiris plugin on the main branch.

  3. Initialize PHPUnit testing environment: Set up your PHPUnit testing environment for Moodle.

  4. Run the test: Execute the following command in your terminal:

    vendor/bin/phpunit mod/quiz/tests/backup/repeated_restore_test.php

Actual Output

If you've followed the steps correctly, you should see output similar to this:

19) mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_duplicate_questions with data set "multichoicewiris" ('multichoicewiris', 'four_of_five_science')
Failed asserting that two strings are equal.
---
+++ 
@@ @@
-'239002'
+'239003'

/var/www/site/mod/quiz/tests/backup/repeated_restore_test.php:423
/var/www/site/lib/phpunit/classes/advanced_testcase.php:76

26) mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_edited_questions with data set "multichoicewiris" ('multichoicewiris', 'four_of_five_science')
Failed asserting that 239000 matches expected '239002'.

/var/www/site/mod/quiz/tests/backup/repeated_restore_test.php:490
/var/www/site/lib/phpunit/classes/advanced_testcase.php:76

29) mod_quiz\backup\repeated_restore_test::test_restore_course_with_same_stamp_questions with data set "multichoicewiris" ('multichoicewiris', 'four_of_five_science')
Failed asserting that two strings are equal.
---
+++ 
@@ @@
-'239000'
+'239002'

/var/www/site/mod/quiz/tests/backup/repeated_restore_test.php:572
/var/www/site/lib/phpunit/classes/advanced_testcase.php:76

33) mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_same_stamp_questions_edited_hints with data set "multichoicewiris" ('multichoicewiris', 'four_of_five_science')
Failed asserting that two strings are equal.
---
+++ 
@@ @@
-'239000'
+'239002'

/var/www/site/mod/quiz/tests/backup/repeated_restore_test.php:657
/var/www/site/lib/phpunit/classes/advanced_testcase.php:76

You'll notice several tests failing with assertions about string equality. This indicates that the restored question IDs don't match the expected IDs.

Diving Deeper into the Error Messages

Let's dissect these error messages a bit more. The core issue, as the error messages highlight, lies in the assertion failures related to string equality. Specifically, the tests are failing because the expected question IDs after the restore do not match the actual question IDs in the restored quiz. This discrepancy is a clear sign that something is going wrong during the restoration process, particularly with how question IDs are being handled.

For instance, in the first failing test, mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_duplicate_questions, the error message shows that the test expected a question ID of '239002', but instead, it found '239003'. This suggests that during the restore, a new question might have been created instead of correctly mapping to the existing one, resulting in a different ID.

Similarly, the error message in mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_edited_questions indicates that the test expected the question ID '239002', but it found '239000'. This could mean that the system failed to update the question ID correctly after an edit, or it might be referencing an older version of the question.

The other failing tests, such as mod_quiz\backup\repeated_restore_test::test_restore_course_with_same_stamp_questions and mod_quiz\backup\repeated_restore_test::test_restore_quiz_with_same_stamp_questions_edited_hints, exhibit similar patterns. They all point to a fundamental problem in how Moodle and the Wiris plugin are handling question IDs during the quiz restoration process.

These errors typically occur in scenarios involving duplicated questions, edited questions, or questions restored from the same timestamp. The underlying cause is often related to the way the plugin interacts with Moodle's backup and restore API, especially when dealing with unique identifiers and references between different entities (like quizzes, questions, and answers).

Understanding these error messages is crucial for diagnosing the problem and implementing the correct fix. By pinpointing the specific tests that are failing and analyzing the ID mismatches, we can gain valuable insights into the root cause of the issue and develop a targeted solution.

Expected Output

Ideally, we want to see this:

No failures

The Fix

Now, for the solution! (This is where the magic happens ✨)

The key to resolving this issue lies in correctly handling the question IDs during the quiz restoration process. This involves ensuring that the Wiris plugin's internal question management is synchronized with Moodle's restoration mechanism. Here's a breakdown of the steps to fix this:

  1. Identify the Problem Area: The first step is to pinpoint the exact location in the code where the question ID mapping is failing. Based on the error messages and the nature of the tests, the issue likely resides in the Wiris plugin's code that handles the restoration of multichoicewiris questions. This code is responsible for updating question IDs, creating new questions when necessary, and maintaining the relationships between quizzes, questions, and answers.

  2. Implement ID Mapping: The core of the fix involves implementing a robust ID mapping mechanism. During the restoration process, the plugin needs to keep track of the old question IDs from the backup and map them to the new IDs in the restored quiz. This mapping ensures that all references to the questions are correctly updated, preventing mismatches and assertion failures.

  3. Use Moodle's API: To achieve proper ID mapping, it's essential to leverage Moodle's backup and restore API. This API provides functions and classes specifically designed for handling ID mappings and ensuring data integrity during restores. By using these tools, the plugin can seamlessly integrate with Moodle's restoration process and avoid conflicts.

  4. Handle Duplicates: One of the main challenges in quiz restoration is dealing with duplicate questions. The fix should include logic to detect and handle duplicate questions appropriately. This might involve creating new questions with unique IDs, or updating existing questions with new data, depending on the specific requirements of the restoration scenario.

  5. Update References: Once the question IDs have been mapped, the plugin needs to update all references to these IDs throughout the quiz and its associated data. This includes references in question text, answers, hints, and any other places where question IDs are used. Failure to update these references can lead to inconsistencies and errors.

  6. Testing: After implementing the fix, it's crucial to thoroughly test it to ensure that it resolves the issue without introducing any new problems. This involves running the failing unit tests (repeated_restore_test.php) and other related tests, as well as performing manual testing with different quiz scenarios. Testing should cover cases with duplicated questions, edited questions, and questions restored from different backups.

  7. Debugging: During testing, it's important to have a solid debugging strategy. This might involve using debugging tools to trace the execution of the restoration code, inspecting variable values, and logging relevant information. Effective debugging can help identify and resolve any remaining issues quickly.

  8. Code Review: Before deploying the fix, it's a good practice to have it reviewed by another developer. A fresh pair of eyes can often spot potential problems or areas for improvement that might have been missed during development and testing. Code review helps ensure the quality and reliability of the fix.

  9. Commit Changes: Once you've identified the necessary code changes, you'll need to commit them to your local branch. Make sure your commit message clearly describes the fix and references the related issue (MDL-83541).

  10. Push Changes: Next, push your local branch to the remote repository. This will make your changes available for review and integration.

  11. Create a Pull Request: Open a pull request (PR) to merge your branch into the main branch. In your PR description, provide a detailed explanation of the issue, the fix, and any testing you've performed.

  12. Address Feedback: Be prepared to address any feedback you receive on your PR. Other developers might have questions, suggestions, or concerns about your changes. Engage in a constructive discussion and make any necessary revisions.

  13. Merge Pull Request: Once your PR has been reviewed and approved, it can be merged into the main branch. This integrates your fix into the codebase.

  14. Verification: After merging, it's a good idea to verify that the fix works as expected in the main branch. This might involve running the unit tests and performing some manual testing.

  15. Deployment: Finally, the fix can be deployed to production environments. Make sure to follow your organization's deployment procedures and monitor the system for any issues after the deployment.

By following these steps, the Wiris plugin can correctly handle question IDs during quiz restoration, resolving the failing unit tests and ensuring data integrity. This fix not only addresses the immediate issue but also improves the overall reliability and robustness of the plugin.

Code Snippet Example (Illustrative)

// Example of ID mapping during restore
$oldQuestionId = $backupRecord->oldid;
$newQuestionId = $this->get_mappingid('question', $oldQuestionId);

if (!$newQuestionId) {
    // Create a new question if it doesn't exist
    $newQuestion = $this->create_new_question($questionData);
    $newQuestionId = $newQuestion->id;
    $this->set_mappingid('question', $oldQuestionId, $newQuestionId);
}

// Use $newQuestionId in the restored quiz

Important: This is a simplified example. The actual implementation might require more complex logic and integration with Moodle's API.

Key Takeaways

  • ID mapping is crucial: Correctly mapping IDs during restore operations is essential for maintaining data integrity.
  • Use Moodle's API: Leveraging Moodle's backup and restore API simplifies the process and ensures compatibility.
  • Test thoroughly: Comprehensive testing is vital to ensure the fix works in various scenarios.

Conclusion

Fixing the repeated_restore_test.php failure involves careful ID mapping and a deep understanding of Moodle's backup and restore process. By addressing these issues, we can ensure the reliable restoration of quizzes and maintain the integrity of course data.

I hope this helps you guys out! Let me know if you have any questions or run into any snags of your own.