Add unit tests for DisposableEvent (void and generic types)

[Copilot]

The non-generic DisposableEvent class lacked test coverage, and the generic DisposableEvent<T> class was missing some tests. Added comprehensive test suite covering all public APIs and edge cases for both types.

Changes Made

1. VoidDisposableEventTest.cs - 12 tests for non-generic DisposableEvent:

   • Uses IEventHandler<Void>[] handlers array with NSubstitute mocks
   • Covers: Publish behavior, subscription disposal, ClearHandlers, Dispose, HandlerCount tracking (including incremental changes), IsDisposed, SnapshotHandlers
   • Mirrors the test patterns from the generic DisposableEventTest

2. DisposableEventTest.cs - Enhanced with 2 additional tests:

   • HandlerCount_IncrementsWithEachSubscription - validates handler count increases as subscriptions are added
   • HandlerCount_DecrementsWhenSubscriptionDisposed - validates handler count decreases as subscriptions are disposed

Test Patterns

Both test files now follow consistent patterns:

• sut naming convention for the system under test
• AAA (Arrange, Act, Assert) structure
• xUnit + FluentAssertions + NSubstitute stack
• MethodName_Scenario_ExpectedBehavior naming convention
• NSubstitute mock handlers with Received()/DidNotReceive() verification
• Assert.All for collection assertions

Testing

• ✅ All 313 tests pass successfully on .NET 8 and .NET 9
• ✅ Code review passed with no issues
• ✅ Security scan passed with no vulnerabilities

The changes ensure both the generic and non-generic DisposableEvent classes have comprehensive, consistent test coverage.

Original prompt

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This section details on the original issue you should resolve

<issue_title>DisposableEvent tests</issue_title>
<issue_description>Unit tests for non generic DisposableEvent (the void type)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes DisposableEvent tests #26

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[Hissal]

Check the file for the generic typed DisposableEvent tests and mirror how those are substituted and checked.

Also add missing tests to the generic event that have been added to the void one such as the incremental handlercount tests.

[Copilot]

Check the file for the generic typed DisposableEvent tests and mirror how those are substituted and checked.

Also add missing tests to the generic event that have been added to the void one such as ...

Updated VoidDisposableEventTest to mirror the generic DisposableEventTest pattern using IEventHandler<Void>[] handlers array with NSubstitute mocks and Assert.All assertions. Also added the two missing incremental HandlerCount tests to DisposableEventTest. Both test files now have 12 tests each with consistent patterns. All 313 tests pass. (commit a582091)

[Hissal]

lgtm