fix: forward wrapped access of interface members via the declaring interface

[vbreuss]

Mocking an interface that inherits two sibling interfaces declaring a member with the same name did not compile: the implicit member forwarded to the wrapped instance through the mocked interface, where the access is ambiguous between the siblings (CS0229 for properties and events, CS0121 for methods and indexers).

Always cast MockRegistry.Wraps to the declaring interface (ContainingType) for interface mocks. This subsumes the special case for explicit implementations (hidden members), whose ExplicitImplementation is the containing type anyway. Class mocks keep forwarding through the mocked class.

[Copilot]

Pull request overview

This PR fixes a source-generator wrapping edge case for interface mocks where a mocked interface inherits multiple sibling interfaces that declare same-named members. The generated forwarding code now casts MockRegistry.Wraps to the declaring interface (ContainingType) so member access is unambiguous and compiles correctly (avoiding CS0229/CS0121), while class mocks continue forwarding through the mocked class type.

Changes:

• Update interface-member forwarding in the source generator to delegate through each member’s declaring interface when wrapping.
• Add runtime and generator tests covering sibling-interface collisions across properties, indexers, methods, and events.
• Update docs to reflect the clarified wrapping/forwarding behavior for interface members.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Tests/Mockolate.Tests/TestHelpers/IChocolateGiftSet.cs	Adds sibling-interface hierarchy used to reproduce/verify ambiguous-member wrapping scenarios.
Tests/Mockolate.Tests/MockTests.WrappingInterfaceTests.cs	Adds runtime wrapping tests proving correct delegation for sibling-interface members.
Tests/Mockolate.SourceGenerators.Tests/MockTests.cs	Adds generator regression tests ensuring generated code delegates via declaring interfaces for sibling collisions.
Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.PropertiesTests.cs	Updates expected generated output for wrapping delegation to use declaring interfaces in base-interface members.
Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.MethodTests.cs	Updates expected generated output for wrapping delegation to use declaring interfaces in base-interface members.
Tests/Mockolate.SourceGenerators.Tests/MockTests.ClassTests.EventsTests.cs	Updates expected generated output for wrapping delegation to use declaring interfaces in base-interface members.
Source/Mockolate.SourceGenerators/Sources/Sources.MockClass.cs	Implements the core generator change: cast wraps to ContainingType for interface mocks when forwarding.
Docs/pages/01-create-mocks.md	Documents that interface members are forwarded through their declaring interfaces (including new hiding and sibling collisions).

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[github-actions]

Test Results

    24 files  ± 0      24 suites  ±0   12m 40s ⏱️ + 1m 16s
 4 377 tests +11   4 375 ✅ +11  2 💤 ±0  0 ❌ ±0 
27 799 runs  +61  27 795 ✅ +61  4 💤 ±0  0 ❌ ±0 

Results for commit 40a5755. ± Comparison against base commit cb55194.

♻️ This comment has been updated with latest results.

[github-actions]

🚀 Benchmark Results

Details

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

AMD EPYC 9V45 2.60GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v4
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Event	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	304.7 ns	2.99 ns	2.80 ns	1.58	1.7 KB	1.00
Mockolate	193.1 ns	3.44 ns	3.22 ns	1.00	1.7 KB	1.00
Imposter	768.4 ns	18.85 ns	17.63 ns	3.98	8.8 KB	5.17
TUnitMocks	112.0 ns	3.58 ns	3.35 ns	0.58	1.34 KB	0.79
Moq	7,515.3 ns	113.15 ns	105.84 ns	38.93	12.51 KB	7.34
NSubstitute	2,881.7 ns	56.91 ns	50.45 ns	14.93	9.05 KB	5.31
FakeItEasy	100,072.4 ns	2,744.54 ns	2,567.25 ns	518.39	15.27 KB	8.97

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 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	340.2 ns	9.63 ns	9.00 ns	0.99	1.93 KB	1.00
Mockolate	1	342.3 ns	4.73 ns	4.20 ns	1.00	1.93 KB	1.00
Imposter	1	553.0 ns	13.10 ns	12.25 ns	1.62	4.04 KB	2.09
TUnitMocks	1	474.4 ns	8.79 ns	8.22 ns	1.39	2.02 KB	1.04
Moq	1	186,694.1 ns	693.69 ns	614.94 ns	545.44	14.73 KB	7.63
NSubstitute	1	6,240.7 ns	70.51 ns	65.96 ns	18.23	9.06 KB	4.70
FakeItEasy	1	6,164.7 ns	78.44 ns	73.37 ns	18.01	8.05 KB	4.17
baseline*	10	677.6 ns	5.93 ns	5.55 ns	1.04	2.14 KB	1.00
Mockolate	10	651.9 ns	7.02 ns	6.57 ns	1.00	2.14 KB	1.00
Imposter	10	1,150.4 ns	13.87 ns	12.30 ns	1.76	5.52 KB	2.58
TUnitMocks	10	1,371.4 ns	28.90 ns	27.03 ns	2.10	3.73 KB	1.74
Moq	10	190,327.8 ns	504.98 ns	394.25 ns	292.00	18.64 KB	8.71
NSubstitute	10	9,472.1 ns	83.32 ns	73.86 ns	14.53	11.52 KB	5.38
FakeItEasy	10	9,755.5 ns	127.99 ns	119.73 ns	14.97	15.42 KB	7.20

Details

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

Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v4
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Indexer	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	1.067 μs	0.0175 μs	0.0163 μs	0.96	3.77 KB	1.00
Mockolate	1	1.112 μs	0.0171 μs	0.0151 μs	1.00	3.77 KB	1.00
Imposter	1	1.128 μs	0.0085 μs	0.0071 μs	1.01	5.16 KB	1.37
Moq	1	168.328 μs	0.6968 μs	0.6518 μs	151.45	20.47 KB	5.44
NSubstitute	1	11.447 μs	0.0376 μs	0.0333 μs	10.30	12.78 KB	3.39
FakeItEasy	1	11.774 μs	0.0581 μs	0.0544 μs	10.59	13.62 KB	3.62
baseline*	10	2.929 μs	0.0082 μs	0.0077 μs	0.98	4.82 KB	1.00
Mockolate	10	2.988 μs	0.0112 μs	0.0105 μs	1.00	4.82 KB	1.00
Imposter	10	2.406 μs	0.0330 μs	0.0292 μs	0.81	7.97 KB	1.65
Moq	10	179.856 μs	1.0002 μs	0.9356 μs	60.19	30 KB	6.22
NSubstitute	10	24.961 μs	0.0602 μs	0.0563 μs	8.35	25.58 KB	5.31
FakeItEasy	10	24.544 μs	0.0708 μs	0.0662 μs	8.21	32.98 KB	6.84

Details

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

AMD EPYC 7763 2.73GHz, 1 CPU, 4 logical and 2 physical cores

.NET SDK 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Callback	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	308.8 ns	3.53 ns	2.76 ns	0.82	1.57 KB	1.00
Mockolate	378.3 ns	6.10 ns	5.70 ns	1.00	1.57 KB	1.00
Imposter	501.4 ns	6.81 ns	6.37 ns	1.33	2.38 KB	1.52
TUnitMocks	562.5 ns	4.68 ns	4.38 ns	1.49	1.99 KB	1.27
Moq	101,164.2 ns	807.59 ns	755.42 ns	267.51	8.88 KB	5.66
NSubstitute	5,016.0 ns	15.58 ns	13.81 ns	13.26	7.71 KB	4.91
FakeItEasy	5,126.1 ns	37.15 ns	34.75 ns	13.55	6.81 KB	4.33

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 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Property	N	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	1	527.8 ns	7.16 ns	6.70 ns	0.89	2.41 KB	1.00
Mockolate	1	594.8 ns	28.31 ns	26.48 ns	1.00	2.41 KB	1.00
Imposter	1	456.3 ns	8.16 ns	7.63 ns	0.77	3.13 KB	1.29
TUnitMocks	1	498.2 ns	7.49 ns	7.00 ns	0.84	1.64 KB	0.68
Moq	1	12,370.6 ns	87.79 ns	77.82 ns	20.83	10.27 KB	4.25
NSubstitute	1	7,971.8 ns	81.74 ns	76.46 ns	13.43	11.45 KB	4.74
FakeItEasy	1	8,829.0 ns	54.81 ns	42.79 ns	14.87	11.24 KB	4.66
baseline*	10	1,054.4 ns	7.69 ns	7.20 ns	0.96	2.91 KB	1.00
Mockolate	10	1,095.2 ns	23.25 ns	21.75 ns	1.00	2.91 KB	1.00
Imposter	10	1,156.4 ns	15.72 ns	13.93 ns	1.06	4.67 KB	1.61
TUnitMocks	10	1,672.0 ns	33.96 ns	31.77 ns	1.53	3.94 KB	1.35
Moq	10	19,486.9 ns	106.44 ns	94.36 ns	17.80	17.03 KB	5.86
NSubstitute	10	18,559.7 ns	76.51 ns	71.57 ns	16.95	21.08 KB	7.25
FakeItEasy	10	20,377.2 ns	127.68 ns	119.43 ns	18.61	30.81 KB	10.60

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 10.0.400

[Host] : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v3
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

CreateMock	Mean	Error	StdDev	Ratio	Allocated	Alloc Ratio
baseline*	14.46 ns	0.085 ns	0.079 ns	0.77	160 B	1.00
Mockolate	18.67 ns	0.288 ns	0.269 ns	1.00	160 B	1.00
Imposter	304.17 ns	6.323 ns	5.914 ns	16.29	2248 B	14.05
TUnitMocks	38.72 ns	0.272 ns	0.255 ns	2.07	200 B	1.25
Moq	1,433.01 ns	5.097 ns	4.767 ns	76.76	2096 B	13.10
NSubstitute	2,007.36 ns	25.526 ns	23.877 ns	107.53	5048 B	31.55
FakeItEasy	1,846.23 ns	17.037 ns	15.103 ns	98.90	2763 B	17.27

baseline* rows show the corresponding Mockolate benchmark from the most recent successful main branch build with results, for regression comparison.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[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]

This is addressed in release v3.4.1.