coverage: improve mutation test coverage (2)

[vbreuss]

This PR enhances mutation test coverage by adding new test cases and improving code clarity in the Mockolate test suite. The changes focus on testing edge cases and improving verification scenarios for indexers, properties, and events.

[Copilot]

Pull request overview

This PR enhances mutation test coverage by adding new test cases and improving code clarity in the Mockolate test suite. The changes focus on testing edge cases and improving verification scenarios for indexers, properties, and events.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Tests/Mockolate.Tests/Verify/VerificationResultTests.cs	Added tests for Match.AnyParameters() verification and null value indexer setting; fixed nullable return type for test interface
Tests/Mockolate.Tests/MockProperties/SetupPropertyTests.cs	Added test to verify multiple properties can store values simultaneously
Tests/Mockolate.Tests/MockIndexers/SetupIndexerTests.cs	Added test to verify multiple indexer values can be stored and retrieved
Tests/Mockolate.Tests/MockEvents/RaiseTests.cs	Added test to verify unsubscribing from one event doesn't affect other subscriptions
Source/Mockolate/MockRegistration.Setup.cs	Replaced magic boolean literal with named constant and added explanatory comment

[vbreuss]

See also #347

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test Results

    14 files  ± 0      14 suites  ±0   5m 16s ⏱️ -37s
 1 830 tests + 5   1 829 ✅ + 5  1 💤 ±0  0 ❌ ±0 
12 207 runs  +35  12 206 ✅ +35  1 💤 ±0  0 ❌ ±0 

Results for commit 42454ee. ± Comparison against base commit 493efc4.

[github-actions]

🚀 Benchmark Results

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.3 LTS (Noble Numbat)

AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.101

[Host] : .NET 10.0.1 (10.0.1, 10.0.125.57005), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
Simple_Mockolate	1.426 μs	0.0056 μs	0.0052 μs	0.2270	-	3.72 KB
Simple_Moq	177.266 μs	1.0836 μs	1.0136 μs	0.4883	-	14.55 KB
Simple_NSubstitute	5.385 μs	0.0146 μs	0.0137 μs	0.5493	0.0076	9.09 KB
Simple_FakeItEasy	6.107 μs	0.0157 μs	0.0147 μs	0.4959	-	8.11 KB

[github-actions]

This is addressed in release v0.49.0.