fix: preserve ref/out/in modifiers when raising events with by-ref delegates

[vbreuss]

This pull request improves the code generation logic for event delegates with by-ref parameters (ref, out, in, and ref readonly) in the mock class source generator. The changes ensure that parameter modifiers are preserved in both method declarations and invocations, and that definite assignment requirements for out parameters are satisfied, preventing potential compiler errors. Additionally, a new test verifies correct behavior for events with ref and out delegate parameters.

Code generation improvements for by-ref parameters:

• Updated FormatParametersWithTypeAndName and FormatParametersAsNames to preserve ref, out, and in modifiers, ensuring generated method signatures and invocations match the original delegate signatures. Introduced the helper method RefKindKeyword for cleaner modifier handling.
• In the mock event raise implementation, added logic to pre-assign default values to out parameters when there are no subscribers, ensuring definite assignment as required by the compiler.
• Modified argument generation for delegate invocations to bind by-ref arguments to local variables with default values, ensuring addressable storage and correct modifier usage.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
91.5% 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   17m 32s ⏱️ + 9m 24s
 3 845 tests +1   3 844 ✅ +1  1 💤 ±0  0 ❌ ±0 
25 049 runs  +3  25 048 ✅ +3  1 💤 ±0  0 ❌ ±0 

Results for commit 493cdb4. ± Comparison against base commit ddd61e7.

[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	399.3 ns	3.83 ns	3.19 ns	1.00	0.01	0.1254	0.0005	2.05 KB	1.00
Event_Moq	13,961.5 ns	107.87 ns	90.07 ns	34.96	0.35	0.7324	-	12.51 KB	6.09
Event_NSubstitute	5,330.1 ns	62.07 ns	48.46 ns	13.35	0.16	0.5493	0.0076	9.05 KB	4.40
Event_FakeItEasy	230,636.0 ns	2,224.41 ns	2,080.71 ns	577.60	6.74	0.7324	0.4883	15.39 KB	7.49
Event_Imposter	1,384.3 ns	26.17 ns	24.48 ns	3.47	0.07	0.5379	0.0153	8.8 KB	4.29
Event_TUnitMocks	180.7 ns	2.87 ns	2.54 ns	0.45	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 7763 2.61GHz, 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	988.9 ns	16.93 ns	15.84 ns	1.00	0.02	0.2460	0.0019	4.03 KB	1.00
Indexer_Moq	1	216,854.2 ns	1,884.60 ns	1,670.65 ns	219.35	3.75	0.9766	0.4883	20.48 KB	5.08
Indexer_NSubstitute	1	9,922.8 ns	79.01 ns	73.90 ns	10.04	0.17	0.7782	-	12.78 KB	3.17
Indexer_FakeItEasy	1	12,276.8 ns	43.32 ns	38.40 ns	12.42	0.19	0.8392	0.0305	13.88 KB	3.44
Indexer_Imposter	1	1,097.7 ns	18.01 ns	16.84 ns	1.11	0.02	0.3147	0.0038	5.16 KB	1.28
Indexer_Mockolate	10	2,714.8 ns	20.52 ns	19.20 ns	1.00	0.01	0.3090	-	5.09 KB	1.00
Indexer_Moq	10	230,596.5 ns	1,134.16 ns	1,060.90 ns	84.95	0.70	1.7090	1.4648	30 KB	5.90
Indexer_NSubstitute	10	24,236.5 ns	44.37 ns	41.50 ns	8.93	0.06	1.5564	0.0305	25.58 KB	5.03
Indexer_FakeItEasy	10	26,485.2 ns	147.23 ns	137.72 ns	9.76	0.08	2.1667	0.0610	35.47 KB	6.97
Indexer_Imposter	10	2,475.1 ns	32.00 ns	29.93 ns	0.91	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 3.12GHz, 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	431.3 ns	3.29 ns	2.75 ns	1.00	0.01	0.1416	0.0010	2.32 KB	1.00
Method_Moq	1	180,290.9 ns	407.15 ns	339.99 ns	418.00	2.67	0.4883	-	14.58 KB	6.28
Method_NSubstitute	1	5,512.2 ns	28.04 ns	24.86 ns	12.78	0.10	0.5569	0.0076	9.12 KB	3.93
Method_FakeItEasy	1	6,165.3 ns	27.52 ns	25.74 ns	14.29	0.10	0.4959	-	8.11 KB	3.50
Method_Imposter	1	561.6 ns	5.07 ns	4.50 ns	1.30	0.01	0.2470	0.0029	4.04 KB	1.74
Method_TUnitMocks	1	670.1 ns	2.53 ns	2.37 ns	1.55	0.01	0.1774	0.0010	2.9 KB	1.25
Method_Mockolate	10	726.4 ns	1.92 ns	1.60 ns	1.00	0.00	0.1545	0.0010	2.53 KB	1.00
Method_Moq	10	183,699.6 ns	593.11 ns	525.78 ns	252.90	0.88	0.9766	0.7324	18.48 KB	7.30
Method_NSubstitute	10	8,132.7 ns	21.94 ns	20.52 ns	11.20	0.04	0.7324	0.0153	12.07 KB	4.77
Method_FakeItEasy	10	9,572.9 ns	47.95 ns	42.50 ns	13.18	0.06	0.9766	0.0305	16.05 KB	6.34
Method_Imposter	10	1,163.6 ns	14.75 ns	13.07 ns	1.60	0.02	0.3376	0.0057	5.52 KB	2.18
Method_TUnitMocks	10	1,651.3 ns	6.76 ns	6.33 ns	2.27	0.01	0.2747	0.0019	4.49 KB	1.77

Details

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

Intel Xeon Platinum 8370C CPU 2.80GHz (Max: 2.79GHz), 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-v4
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	670.4 ns	2.64 ns	2.34 ns	1.00	0.00	0.1049	-	2.58 KB	1.00
Property_Moq	1	11,155.9 ns	17.58 ns	13.73 ns	16.64	0.06	0.3662	-	10.39 KB	4.03
Property_NSubstitute	1	7,630.1 ns	21.76 ns	20.35 ns	11.38	0.05	0.4578	-	11.45 KB	4.44
Property_FakeItEasy	1	8,300.8 ns	23.17 ns	19.35 ns	12.38	0.05	0.4578	-	11.25 KB	4.36
Property_Imposter	1	571.4 ns	4.00 ns	3.12 ns	0.85	0.01	0.1268	0.0010	3.13 KB	1.21
Property_TUnitMocks	1	951.4 ns	4.74 ns	4.43 ns	1.42	0.01	0.1020	-	2.51 KB	0.97
Property_Mockolate	10	1,364.9 ns	6.30 ns	5.26 ns	1.00	0.01	0.1240	-	3.07 KB	1.00
Property_Moq	10	17,992.5 ns	47.00 ns	41.66 ns	13.18	0.06	0.7324	-	18.28 KB	5.95
Property_NSubstitute	10	16,968.0 ns	27.76 ns	21.67 ns	12.43	0.05	0.8545	-	21.08 KB	6.87
Property_FakeItEasy	10	19,611.0 ns	37.33 ns	34.92 ns	14.37	0.06	1.2512	0.0305	30.8 KB	10.03
Property_Imposter	10	1,451.4 ns	8.39 ns	7.85 ns	1.06	0.01	0.1888	0.0019	4.67 KB	1.52
Property_TUnitMocks	10	2,866.8 ns	9.91 ns	9.27 ns	2.10	0.01	0.1869	-	4.66 KB	1.52

Details

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

AMD EPYC 7763 2.45GHz, 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	388.6 ns	2.13 ns	1.99 ns	1.00	0.01	0.1197	-	1.96 KB	1.00
Callback_Moq	95,237.4 ns	341.28 ns	302.53 ns	245.10	1.43	0.4883	0.2441	8.88 KB	4.53
Callback_NSubstitute	4,112.3 ns	7.45 ns	6.61 ns	10.58	0.05	0.4730	0.0076	7.74 KB	3.95
Callback_FakeItEasy	4,526.6 ns	12.36 ns	10.32 ns	11.65	0.06	0.4120	0.0153	6.81 KB	3.47
Callback_Imposter	397.6 ns	0.90 ns	0.76 ns	1.02	0.01	0.1454	0.0010	2.38 KB	1.22
Callback_TUnitMocks	650.5 ns	7.88 ns	7.37 ns	1.67	0.02	0.1602	0.0010	2.63 KB	1.34

[github-actions]

This is addressed in release v3.0.0.