Adding tests for filewatcher sources

[codegefluester]

Auto-discovers file watcher sources and tests that they work correctly. We exclude Tekken for now since I do not know what the file extension is yet.

[Copilot]

Pull request overview

Adds an xUnit-based test suite that auto-discovers FileWatcherSourceBase implementations via reflection and validates key behaviors (startup scan, file create detection, subdirectory watching, debouncing / single-emission).

Changes:

• Added FileWatcherSourceTests to exercise file-watcher sources against real filesystem events.
• Added reflection-based discovery helpers (FileWatcherSourceDiscovery) and xUnit MemberData generator (FileWatcherTestData).
• Introduced basic exclusions (Tekken8) and source grouping by subdirectory support.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 9 comments.

File	Description
GamesDat.Tests/Helpers/FileWatcherTestData.cs	Generates xUnit MemberData for discovered file watcher sources (and subdirectory groupings).
GamesDat.Tests/Helpers/FileWatcherSourceDiscovery.cs	Reflection-based discovery + pattern/subdirectory extraction + source instantiation helper.
GamesDat.Tests/FileWatcherSourceTests.cs	New parameterized tests validating file watcher source behavior on the filesystem.

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[codegefluester]

Review Comment Responses

Thank you for the thorough review! I've addressed 7 of the 9 comments in commit 4801846. Here's a summary:

✅ Addressed Comments

1. Type-Safe Exclusions (FileWatcherTestData.cs:27, 60)

• Changed from string comparison to typeof(Tekken8ReplayFileSource)
• Added explicit import for refactor-safety

2. Resource Management (FileWatcherSourceTests.cs:60, 145, 230, 300, 382, 468)

• Added using var source to all test methods for proper disposal
• Ensures FileSystemWatcher resources are cleaned up

3. Reliable Cleanup (FileWatcherSourceTests.cs - all async tests)

• Added try/finally blocks to all test methods
• Guarantees CTS cancellation and watchTask awaiting even on assertion failures

4. Complete Source Validation (FileWatcherSourceTests.cs:549-576)

• Changed AllDiscoveredSources_AreInstantiable() to use DiscoverAllSources() directly
• Validates all sources including explicit pattern checks (no silent exclusions)

5. Comprehensive Pattern Discovery (FileWatcherSourceDiscovery.cs:96-130)

• GetDefaultOptions() now supports both ApplyDefaults(FileWatcherOptions) and ApplyDefaults(string?)
• Tries FileWatcherOptions overload first, then falls back to string overload
• Discovers patterns from all source implementations

6. Fail-Fast Pattern Retrieval (FileWatcherSourceDiscovery.cs:56-68)

• GetExpectedPatterns() now throws InvalidOperationException instead of returning empty
• Test failures are explicit and debuggable

7. Pattern Validation in Test Data (FileWatcherTestData.cs:32-38, 71-77)

• AllSources() and SourcesWithSubdirectories() throw when patterns are empty
• Ensures test coverage, fails loudly if configuration is incomplete

📝 Not Addressed (Style Suggestions)

8 & 9. Using explicit .Where() instead of continue

I've opted to keep the current continue pattern for the following reasons:

1. Early Exit Clarity: The continue statements serve as early-exit guards that are immediately visible when reading the loop. This makes the filtering logic explicit and easy to understand at a glance.

2. Maintainability: With multiple filtering conditions (Tekken8 exclusion, subdirectory check, pattern validation), chaining .Where() clauses would require either:

   • Multiple .Where() calls which is less efficient (multiple enumerations)
   • Complex lambda predicates that are harder to read and debug
   • Variable captures in closures

3. Debug-Friendly: With continue, each filtering condition can be individually debugged and has its own explanatory comment. The loop body shows exactly what gets yielded.

4. Common Pattern: This pattern is idiomatic in C# for test data generation methods where conditions need documentation and the filtering logic benefits from being explicit.

If you feel strongly about using .Where(), I'm happy to refactor, but I believe the current approach is more maintainable for this use case.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

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