Development: Fix flaky LectureIntegrationTest

[bassner]

Checklist

General

• This is a small issue that I tested locally and was confirmed by another developer on a test server.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• I strictly followed the server coding and design guidelines.

Motivation and Context

The test testCreateLectureSeriesAndCorrectLectureAndChannelNames in LectureIntegrationTest was flaky, failing approximately 50% of the time in CI/CD with:

org.opentest4j.AssertionFailedError: 
expected: "Requirements"
 but was: "Lecture 1"

Description

Root Cause: In initTestCase(), course1.getLectures() returns a Set<Lecture> with non-deterministic iteration order. The test then called getFirst() and getLast() on this set converted to a list, causing lecture1 and lecture2 to be assigned to different physical lectures between test runs.

Fix: Sort lectures by startDate before assigning them to ensure lecture1 is always the chronologically earlier lecture and lecture2 is the later one.

// Before:
var lectures = this.course1.getLectures().stream().toList();

// After:
var lectures = this.course1.getLectures().stream().sorted(Comparator.comparing(Lecture::getStartDate)).toList();

Steps for Testing

1. Run the test multiple times locally:

   ./gradlew test --tests "de.tum.cit.aet.artemis.lecture.LectureIntegrationTest.testCreateLectureSeriesAndCorrectLectureAndChannelNames" --rerun-tasks

2. Verify it passes consistently (tested 5 consecutive runs successfully)

Review Progress

Code Review

• Code Review 1
• Code Review 2

Manual Tests

• Test 1 (ran test 5 times locally, all passed)

Test Coverage

Class/File	Line Coverage	Confirmation (assert/expect)
LectureIntegrationTest.java	N/A (test file)	✅

Summary by CodeRabbit

• Tests
  • Improved test reliability by enforcing deterministic ordering when preparing and retrieving lecture lists, ensuring consistent assertions and more stable test execution.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

Test updated to enforce deterministic ordering by sorting lecture lists by startDate in both initialization and post-creation retrieval paths; local variable lectures renamed to lecturesAfter and all assertions and downstream references updated to use the sorted collection.

Changes

Cohort / File(s)	Change Summary
Deterministic test ordering src/test/java/de/tum/cit/aet/artemis/lecture/LectureIntegrationTest.java	Adds sorting by startDate to lecture lists in initTestCase and in the post-creation retrieval (lecturesAfter). Renames local variable from lectures to lecturesAfter and updates all assertions and downstream derivations (firstLecture, secondLecture, etc.) to use the sorted collection. No public API or exported declarations changed.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• Single test file with consistent, repetitive edits (sorting insertion and variable rename).
• Review focus:
  • Ensure all occurrences of the renamed variable were updated.
  • Confirm both locations apply identical sorting by startDate.
  • Validate assertions still reflect intended test semantics (order-independent comparisons now use a consistently ordered source).

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Development: Fix flaky LectureIntegrationTest' directly addresses the main change: fixing a flaky test in LectureIntegrationTest by sorting lectures deterministically.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch bugfix/lectures/flaky-series-test

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[github-actions]

End-to-End (E2E) Test Results Summary

	Tests	Passed ☑️	Skipped ⚠️	Failed ❌️	Time ⏱
End-to-End (E2E) Test Report	215 ran	211 passed	3 skipped	1 failed	1h 3m 29s 143ms

Test	Result	Time ⏱
End-to-End (E2E) Test Report
e2e/exercise/programming/ProgrammingExerciseParticipation.spec.ts
ts.Programming exercise participation › Programming exercise team participation › Check team participation › Instructor checks the participation	❌ failure	8s 252ms