coverage: add MockRegistry.Interactions edge case tests

[vbreuss]

This pull request adds important test coverage for edge cases in the MockRegistry property setup and access logic, ensuring correct behavior when using the optimized member-id lookup paths. It also adds comments clarifying why certain mutation testing suppressions are safe. The changes improve the reliability of the property setup resolution and document subtle implementation details.

Test coverage improvements:

• Added a test to ensure that when the member-id table contains a null entry, GetPropertyFast correctly falls back to the slower path without throwing an exception.
• Added a test to verify that when both a member-id-based and a dictionary-based property setup exist for the same property, SetPropertyFast uses the member-id setup in the default scope.
• Added a test to ensure that when a scenario is active, SetPropertyFast routes to the scenario-specific setup instead of the member-id table setup.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube Cloud

[github-actions]

Test Results

    21 files  ± 0      21 suites  ±0   9m 0s ⏱️ +5s
 3 886 tests + 3   3 884 ✅ + 3  2 💤 ±0  0 ❌ ±0 
25 220 runs  +21  25 216 ✅ +21  4 💤 ±0  0 ❌ ±0 

Results for commit 51c99e8. ± Comparison against base commit ffa9d1c.

[github-actions]

🚀 Benchmark Results

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 9V74 2.60GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
Event_Mockolate	359.8 ns	7.32 ns	6.85 ns	1.00	0.03	0.1254	0.0005	2.05 KB	1.00
Event_Moq	14,616.9 ns	96.50 ns	85.55 ns	40.64	0.78	0.7324	-	12.93 KB	6.29
Event_NSubstitute	5,324.8 ns	43.18 ns	40.39 ns	14.80	0.29	0.5493	0.0076	9.05 KB	4.40
Event_FakeItEasy	229,195.8 ns	706.96 ns	661.29 ns	637.24	11.87	0.7324	0.4883	15.39 KB	7.49
Event_Imposter	1,436.9 ns	22.53 ns	21.08 ns	4.00	0.09	0.5379	0.0153	8.8 KB	4.29
Event_TUnitMocks	176.7 ns	1.71 ns	1.51 ns	0.49	0.01	0.0837	0.0002	1.37 KB	0.67

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 9V74 2.87GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	N	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
Indexer_Mockolate	1	955.5 ns	16.88 ns	14.96 ns	1.00	0.02	0.2460	0.0019	4.03 KB	1.00
Indexer_Moq	1	164,020.6 ns	1,086.61 ns	963.25 ns	171.70	2.75	0.9766	0.4883	20.37 KB	5.05
Indexer_NSubstitute	1	8,463.3 ns	146.68 ns	137.21 ns	8.86	0.19	0.7782	-	12.78 KB	3.17
Indexer_FakeItEasy	1	9,566.6 ns	74.27 ns	69.47 ns	10.01	0.17	0.8392	0.0305	13.88 KB	3.44
Indexer_Imposter	1	875.8 ns	6.76 ns	5.99 ns	0.92	0.02	0.3147	0.0048	5.16 KB	1.28
Indexer_Mockolate	10	2,461.4 ns	16.38 ns	15.32 ns	1.00	0.01	0.3090	-	5.09 KB	1.00
Indexer_Moq	10	178,829.0 ns	1,061.58 ns	993.00 ns	72.66	0.59	1.7090	1.4648	29.89 KB	5.88
Indexer_NSubstitute	10	20,508.4 ns	42.58 ns	39.83 ns	8.33	0.05	1.5564	0.0305	25.58 KB	5.03
Indexer_FakeItEasy	10	21,034.2 ns	48.56 ns	43.05 ns	8.55	0.05	2.1667	0.0610	35.47 KB	6.97
Indexer_Imposter	10	2,055.5 ns	32.16 ns	30.09 ns	0.84	0.01	0.4845	0.0076	7.97 KB	1.57

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 3.23GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	N	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
Method_Mockolate	1	440.8 ns	4.29 ns	4.01 ns	1.00	0.01	0.1416	0.0010	2.32 KB	1.00
Method_Moq	1	182,246.8 ns	700.46 ns	620.94 ns	413.45	3.88	0.4883	-	14.58 KB	6.28
Method_NSubstitute	1	5,624.4 ns	23.03 ns	21.55 ns	12.76	0.12	0.5569	0.0076	9.12 KB	3.93
Method_FakeItEasy	1	6,029.7 ns	15.40 ns	13.65 ns	13.68	0.12	0.4959	-	8.11 KB	3.50
Method_Imposter	1	577.5 ns	22.97 ns	21.48 ns	1.31	0.05	0.2470	0.0029	4.04 KB	1.74
Method_TUnitMocks	1	722.9 ns	20.45 ns	19.13 ns	1.64	0.04	0.1774	0.0010	2.9 KB	1.25
Method_Mockolate	10	750.5 ns	13.95 ns	13.05 ns	1.00	0.02	0.1545	0.0010	2.53 KB	1.00
Method_Moq	10	186,777.6 ns	879.87 ns	779.99 ns	248.94	4.30	0.9766	0.7324	18.48 KB	7.30
Method_NSubstitute	10	8,346.8 ns	31.41 ns	27.84 ns	11.12	0.19	0.7324	0.0153	12.07 KB	4.77
Method_FakeItEasy	10	9,354.9 ns	111.64 ns	104.43 ns	12.47	0.25	0.9766	0.0305	16.05 KB	6.34
Method_Imposter	10	1,264.2 ns	16.17 ns	15.13 ns	1.68	0.03	0.3376	0.0057	5.52 KB	2.18
Method_TUnitMocks	10	1,763.7 ns	15.22 ns	14.23 ns	2.35	0.04	0.2747	0.0019	4.49 KB	1.77

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 3.01GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	N	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
Property_Mockolate	1	613.4 ns	9.14 ns	8.55 ns	1.00	0.02	0.1574	0.0010	2.58 KB	1.00
Property_Moq	1	11,911.9 ns	62.06 ns	48.45 ns	19.42	0.27	0.6104	-	10.39 KB	4.03
Property_NSubstitute	1	7,905.4 ns	41.34 ns	34.52 ns	12.89	0.18	0.6866	-	11.45 KB	4.44
Property_FakeItEasy	1	8,563.3 ns	163.76 ns	153.18 ns	13.96	0.31	0.6866	-	11.24 KB	4.36
Property_Imposter	1	460.0 ns	7.56 ns	6.70 ns	0.75	0.01	0.1912	0.0019	3.13 KB	1.21
Property_TUnitMocks	1	746.1 ns	11.30 ns	10.57 ns	1.22	0.02	0.1526	0.0010	2.51 KB	0.97
Property_Mockolate	10	1,093.9 ns	18.38 ns	17.19 ns	1.00	0.02	0.1869	-	3.07 KB	1.00
Property_Moq	10	18,547.0 ns	106.43 ns	99.56 ns	16.96	0.27	1.0986	-	18.28 KB	5.95
Property_NSubstitute	10	17,662.0 ns	177.62 ns	166.15 ns	16.15	0.29	1.2817	0.0305	21.08 KB	6.87
Property_FakeItEasy	10	20,628.2 ns	139.62 ns	130.60 ns	18.86	0.31	1.8616	-	30.81 KB	10.03
Property_Imposter	10	1,343.1 ns	11.58 ns	10.26 ns	1.23	0.02	0.2842	0.0019	4.67 KB	1.52
Property_TUnitMocks	10	2,311.6 ns	9.75 ns	8.65 ns	2.11	0.03	0.2823	-	4.66 KB	1.52

Details

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.4 LTS (Noble Numbat)

AMD EPYC 7763 2.60GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.203

[Host] : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Gen1	Allocated	Alloc Ratio
Callback_Mockolate	408.0 ns	3.78 ns	3.53 ns	1.00	0.01	0.1197	-	1.96 KB	1.00
Callback_Moq	96,263.3 ns	376.70 ns	333.93 ns	235.95	2.13	0.4883	0.2441	8.99 KB	4.59
Callback_NSubstitute	4,541.5 ns	16.83 ns	14.92 ns	11.13	0.10	0.4730	0.0076	7.74 KB	3.95
Callback_FakeItEasy	4,847.8 ns	24.30 ns	21.54 ns	11.88	0.11	0.4120	0.0153	6.81 KB	3.47
Callback_Imposter	414.7 ns	4.46 ns	3.72 ns	1.02	0.01	0.1454	0.0010	2.38 KB	1.22
Callback_TUnitMocks	599.5 ns	6.41 ns	5.68 ns	1.47	0.02	0.1602	0.0010	2.63 KB	1.34

[github-actions]

This is addressed in release v3.0.0.