perf(source-gen): make TestMetadataGenerator pipeline values equatable

[thomhurst]

Summary

TestMetadataGenerator passed symbol-holding models through its incremental pipeline. TestMethodMetadata compared by symbol (and held the GeneratorAttributeSyntaxContext, which keeps the semantic model and compilation alive), and InheritsTestsClassMetadata had no equality at all. Symbols from a new compilation never compare equal, so every compilation marked every test Modified. The generator then:

• regrouped every class and rebuilt its code strings in GroupMethodsByClass
• regenerated and re-added every generic test file and every [InheritsTests] file

This PR makes the pipeline carry only equatable values, so the grouping and output steps are cached unless a test's generated code actually changes.

Generated output is unchanged. All TUnit.Core.SourceGenerator.Tests snapshots pass without changes. I also hashed the complete generated output of a synthetic 20,000-test project (plain, async, [Arguments], generic and [InheritsTests] tests) with the origin/main generator and with this branch, and the hashes match.

Design choice

The attribute transforms now return only the declaration node (MethodDeclarationSyntax / ClassDeclarationSyntax). A following step does the rest:

FAWMN(node) -> Combine(enabled) -> Combine(CompilationProvider) -> Select(generate strings) -> Where(not null)

That Select resolves the symbol against the current compilation and produces a string-only TestMethodGenerationResult. For a non-generic test this is the pre-generated per-class pieces. For a generic or inherited test it is the complete hint name and source (or an error record). For [InheritsTests], it is an EquatableArray of those results.

I considered generating the strings directly in the attribute transform, but that transform cannot see EnableTUnitSourceGeneration. Reflection-mode builds, which the docs recommend setting that property for to speed up builds, would then have paid for full code generation. Putting generation after Combine(enabled) keeps those builds free of symbol work.

The generation step still runs on every compilation. It has to, because a test's output depends on symbols in other files (base classes, data sources, constants). Before this PR the attribute transform re-ran on every compilation as well, so this is not a new cost. What changes is that its output is now equatable, so everything downstream stays cached.

The pipeline no longer holds symbols, semantic models or syntax contexts. The syntax node it keeps only keeps its own syntax tree alive, and the compilation holds that tree anyway. Class-level code (instance factory, shared fields, reflection accessors) is computed once per class per compilation in a per-compilation GenerationState, held in a ConditionalWeakTable like the previous CompilationContext. The case N: label and attribute-group index depend on a method's position in its class, so they are assigned when grouping, which is now cheap and string-only.

Changes, per item

1. Equatable test pipeline. Implemented as described above. TestMethodMetadata is now a plain working object: no Equals, and the Context, TestAttribute and MethodSyntax members are removed. The first two were only used for .SemanticModel.Compilation, and the last was never read. Generation code uses CompilationContext.Compilation. GroupMethodsByClass now works only on strings and groups by fully qualified class name, which identifies a type within a compilation just like symbol equality.

2. [InheritsTests] equality. InheritsTestsClassMetadata is replaced by InheritsTestsClassResult, a record holding an EquatableArray<TestMethodGenerationResult>. If a test fails to generate, the error is stored as a TestGenerationError record (file path and spans, with no Location or syntax tree) and reported as the same TUNIT0999 diagnostic. This now also covers per-class pre-generation of non-generic tests. On main, an exception there escaped the grouping step and failed the whole generator.

3. Dead code removed. Each item was checked with a search across src and tests. The Roslyn variant projects link ..\TUnit.Core.SourceGenerator\**\*.cs, so deleting a file removes it from every variant. Roslyn44, Roslyn47 and Roslyn414 all build cleanly.

   • SharedLocalsCode / PreGenerateSharedLocals: computed for every class and never emitted.
   • PreGenerateAttributeFactoryBody: unused. This also made GetAllAttributes unused, so it is removed too.
   • TestMethodSourceCode.MethodId: computed for every method, with de-duplication and FileNameHelper.GetSafeMethodId, and never read. Both are removed.
   • CodeGenerators/Helpers/GenericTypeHelper.cs: unused, and in the Inject.NET.SourceGenerator namespace. InstanceFactoryGenerator only emits a string that references the runtime TUnit.Core.Helpers.GenericTypeHelper.
   • Analyzers/ITestAnalyzer.cs, Analyzers/TestMethodAnalyzer.cs, Models/TestMetadataGenerationContext.cs, Models/TestDescriptorModel.cs (TestMethodModel/TestClassModel), Models/Extracted/TestMethodModel.cs and Models/HooksDataModel.cs: all unused.
   • Models/Extracted/DataSourceModel.cs and Enums/HookLocationType.cs: only referenced by the files above.

4. GloballyQualified() cache: skipped. I tried a ConditionalWeakTable<ISymbol, string> keyed by symbol identity. It was thread-safe and correct for nullable annotations, but there was no measurable difference on the 20,000-test benchmark (median full run, unrelated edit and test edit were within run-to-run noise across 3 × 15 iterations). As the task allows, I left it out.

5. RegisterImplementationSourceOutput: not changed. It would be safe for compilation: user code never references *_TestSource or TUnit_TestRegistration, and InfrastructureGenerator declares the partial shell on its own. But it would hide the generated test sources in the IDE, which users rely on to inspect and debug generated tests, and Rider and VS handle implementation-only outputs differently. With this PR these outputs are already cached on unrelated edits, so the remaining design-time gain would be limited to edits that change a test. I did not think that was worth the change in IDE behavior.

6. Tracking names and incrementality tests. Tracking names are added: TestMethodSyntax, TestMethodResults, ClassTestGroups, InheritsTestsSyntax and InheritsTestsResults. The new TestMetadataGeneratorIncrementalTests checks four cases:

   • An unrelated edit: results are Unchanged, and ClassTestGroups and every SourceOutput step are Cached.
   • Renaming one test: only that result is Modified, only that class's group is Modified, and the other class and the inherited tests are Unchanged.
   • Renaming a base-class test: the [InheritsTests] result is Modified and the class groups stay cached.
   • EnableTUnitSourceGeneration=false: no sources, diagnostics or results are produced.

   TestHelper gains a multi-tree ReplaceSyntaxTreeText and step-reason helpers.

Tests run

• tests/TUnit.Core.SourceGenerator.Tests on net10.0, net8.0 and net472: 156 passed and 1 skipped (already skipped) on each, with no snapshot changes. This includes the existing TestMetadataIncrementalTests.
• tests/TUnit.SourceGenerator.IncrementalTests: all 17 tests pass, including the 4 new ones. This project has no test runner package and is not run in CI; dotnet test is rejected by global.json (MTP only) and dotnet vstest finds no tests. I ran it locally by invoking the [Fact] methods through a small reflection harness.
• tests/TUnit.TestProject in source-gen mode (net10.0), one filter per run:
  • /*/TUnit.TestProject.Bugs._4431/*/* (generic classes and methods): 47 passed, 1 failed. The failure is CompositionPatternDoesNotWork_4431, marked [EngineTest(ExpectedResult.Failure)].
  • /*/TUnit.TestProject.Bugs._4440/*/* (generic method discovery): 25/25 passed.
  • /*/TUnit.TestProject.AbstractTests/*/* ([InheritsTests]): 2 passed, 1 failed. The failure is ConcreteClass1.AssertClassName, which is designed to fail: GetName() returns "Concrete1" and the test compares it with the type name.
  • /*/TUnit.TestProject/AsyncInheritedTestsRepro/* (cross-assembly [InheritsTests]): 8/8 passed.
  • /*/TUnit.TestProject.Bugs._1889/*/* (inherited tests): 5/5 passed.
• Roslyn44, Roslyn47 and Roslyn414 generator variants build with no warnings.

Timing (synthetic 20,000 tests in 1,000 files, Roslyn47 generator, median of 15, noisy shared machine)

	main	this PR
Unrelated edit	500–580 ms	455–530 ms
Test edit	510–605 ms	460–555 ms

In both cases, 1,201 generated files are no longer rebuilt and re-added on each edit. Most of the remaining time is binding symbols in the new compilation, which the generation step has to do. The larger IDE benefit is that generated syntax trees stay the same, so they are not re-parsed or re-bound after unrelated edits.

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of inherited tests and retained source location details for clearer generation error reporting.
• Refactor
  • Test generation now updates results for affected changes while reusing results for unrelated edits.
• Tests
  • Added coverage for incremental updates, inherited-test changes, and behavior when source generation is disabled.

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📝 Code Review	✅ Completed 2026-09-28T19:04:31.869589Z	e6f33d0	PR opened

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📝 Walkthrough

Walkthrough

The source generator now uses incremental syntax processing, compilation-scoped caches, and structured results for test and inherited-test generation. It pre-generates non-generic method code and groups it by class. New tests check tracked incremental steps and disabled generation.

Changes

Test metadata generation

Layer / File(s)	Summary
Generation result and metadata contracts src/TUnit.Core.SourceGenerator/Models/TestMethodGenerationResult.cs, src/TUnit.Core.SourceGenerator/Models/TestMethodMetadata.cs, src/TUnit.Core.SourceGenerator/Analyzers/*, src/TUnit.Core.SourceGenerator/Models/*, src/TUnit.Core.SourceGenerator/CodeGenerators/Helpers/GenericTypeHelper.cs, src/TUnit.Core.SourceGenerator/Helpers/FileNameHelper.cs, src/TUnit.Core.SourceGenerator/Enums/HookLocationType.cs	Added records for generated method results, per-class code, standalone sources, errors, and inherited-test results. Revised TestMethodMetadata and removed the prior analyzer interfaces, models, generation context, and listed helpers.
Incremental discovery and result emission src/TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs	Test and inherited-test generation now use incremental syntax steps and shared compilation state. Generation returns structured results or errors, which are emitted as sources or TUNIT0999 diagnostics.
Per-class code preparation and validation src/TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs, src/TUnit.Core.SourceGenerator/Models/ClassTestGroup.cs, src/TUnit.Core.SourceGenerator/Models/TestMethodSourceCode.cs, tests/TUnit.Core.SourceGenerator.Tests/TestMetadataIncrementalTests.cs	The generator pre-generates method code and groups it by fully qualified class name. Grouping assigns method and attribute-group indexes, and the class-level invoke switch uses pre-generated invoke bodies. Tests check tracked-step behavior for edits and that disabled generation produces no sources or diagnostics.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~55 minutes

Change: Refactor

Sequence Diagram(s)

sequenceDiagram
  participant TestMethodSyntaxStep
  participant TestMetadataGenerator
  participant GenerationState
  participant SourceProductionContext
  TestMethodSyntaxStep->>TestMetadataGenerator: provide test syntax
  TestMetadataGenerator->>GenerationState: resolve symbols and generate results
  GenerationState-->>TestMetadataGenerator: return sources or errors
  TestMetadataGenerator->>SourceProductionContext: emit sources or TUNIT0999 diagnostics

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Merge Risk: ⚪ Minimal · up to d97de

The generator continues to associate grouped test entries with their intended methods, and the examined metadata paths show no concrete user-facing regression. No actionable merge blocker is established; routine build and test checks remain appropriate.

Security Architecture Review

Security architecture risk: 🔵 Low · up to d97de

The change reorganizes test generation and caching without evidence that it widens who can trigger generation or bypasses the opt-out control. Generated-code consistency across changing builds remains the principal residual risk.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The changed emission path operates on attributed test declarations in the current compilation. The examined entrypoint does not show a new input authority or destination beyond generated sources and diagnostics.

Trust Boundaries and Controls

• observed — The attribute filters and build-property opt-out precede symbol-based generation; symbol lookup uses generation state obtained for the supplied compilation.

Resilience and Maintainability Implications

• observed — Non-cancellation failures while preparing a direct per-class method become error results, which the output callback reports as diagnostics rather than adding source for that result.

Hardening Proposals

• proposed — Exercise enabled-to-disabled-to-enabled changes with one incremental driver to establish that generated output is withdrawn and restored across configuration transitions, not just absent in an initially disabled run.

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Docstring Coverage	⚠️ Warning	Docstring coverage is 17.19% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 64 functions across 7 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

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Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: making TestMetadataGenerator pipeline values equatable to improve incremental source-generation performance.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[github-actions]

Review

Solid change. The pipeline now carries only string/record values (TestMethodGenerationResult, PerClassTestMethodCode, EquatableArray), so Roslyn can cache the grouping and output steps. Dropping GeneratorAttributeSyntaxContext also stops the semantic model and compilation from being retained. The PR states that generated output is unchanged (snapshots plus a 20k-test hash comparison), and new incremental tests cover the caching.

Observations, none blocking:

• Per-compilation cost is still O(n). The Combine(CompilationProvider) Select re-runs symbol work for every test on every compilation. Only the downstream steps get cheaper. The PR description acknowledges this trade-off, and the enabled gate correctly keeps reflection-mode builds from paying for it. A cheaper option later would be to extract an equatable per-test model in the transform, but that is a larger refactor.
• GenerationState._lastSemanticModel is a plain field. The race is benign, because the value is read into a local and the tree is re-checked. If the Select can run concurrently, a comment saying so would help, or use Interlocked/a tuple swap. The assumption that tests arrive grouped by syntax tree is only a performance heuristic, which is fine.
• TestGenerationError keeps FilePath, TextSpan and LinePositionSpan. That avoids retaining a syntax tree and keeps value equality. Good.
• Tests: confirm the incremental tests assert both Unchanged/Cached on ClassTestGroupsStep after an unrelated edit and a Modified result after a real change to a test.

Approving in spirit.

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Inline comments:
Review comments at
@src/TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs:
- Around line 237-240: In TestMethodResultsStep, wrap the non-generic per-class
pre-generation calls to GetClassLevelCode and PreGeneratePerClassMethodCode so
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• src/TUnit.Core.SourceGenerator/Analyzers/ITestAnalyzer.cs
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• src/TUnit.Core.SourceGenerator/CodeGenerators/Helpers/GenericTypeHelper.cs
• src/TUnit.Core.SourceGenerator/Enums/HookLocationType.cs
• src/TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs
• src/TUnit.Core.SourceGenerator/Helpers/FileNameHelper.cs
• src/TUnit.Core.SourceGenerator/Models/ClassTestGroup.cs
• src/TUnit.Core.SourceGenerator/Models/Extracted/DataSourceModel.cs
• src/TUnit.Core.SourceGenerator/Models/Extracted/TestMethodModel.cs
• src/TUnit.Core.SourceGenerator/Models/HooksDataModel.cs
• src/TUnit.Core.SourceGenerator/Models/TestDescriptorModel.cs
• src/TUnit.Core.SourceGenerator/Models/TestMetadataGenerationContext.cs
• src/TUnit.Core.SourceGenerator/Models/TestMethodGenerationResult.cs
• src/TUnit.Core.SourceGenerator/Models/TestMethodMetadata.cs
• src/TUnit.Core.SourceGenerator/Models/TestMethodSourceCode.cs
• tests/TUnit.SourceGenerator.IncrementalTests/TestHelper.cs
• tests/TUnit.SourceGenerator.IncrementalTests/TestMetadataGeneratorIncrementalTests.cs

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• src/TUnit.Core.SourceGenerator/Models/ClassTestGroup.cs
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• src/TUnit.Core.SourceGenerator/Enums/HookLocationType.cs
• src/TUnit.Core.SourceGenerator/Helpers/FileNameHelper.cs
• src/TUnit.Core.SourceGenerator/Models/Extracted/DataSourceModel.cs
• src/TUnit.Core.SourceGenerator/Models/TestDescriptorModel.cs
• src/TUnit.Core.SourceGenerator/Models/TestMetadataGenerationContext.cs
• src/TUnit.Core.SourceGenerator/CodeGenerators/Helpers/GenericTypeHelper.cs
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• src/TUnit.Core.SourceGenerator/Analyzers/TestMethodAnalyzer.cs

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[github-actions]

Review of #6918

I couldn't run the automated code-review skill, so I read TestMetadataGenerator.cs in pr-head/ by hand. I did not build the PR or run its tests. I also did not read the model, helper, or test files in full.

Overall: the design is sound. The attribute transforms now return only the declaration node, and code generation moves into a Combine(enabled), then Combine(Compilation), then Select step that produces string-only, equatable results. That fixes the cause described in the PR: symbol-holding models never compare equal across compilations. It also keeps reflection-mode builds (EnableTUnitSourceGeneration=false) from doing any symbol work. Tracking-name constants and the incremental tests make the caching behaviour checkable. The PR says the snapshot tests pass unchanged and that the output hash matches main on a 20k-test project. I haven't reproduced either.

Points to consider (none blocking):

1. Every compilation still regenerates every test's strings. The Select depends on CompilationProvider, so it re-runs for all tests on each edit. The savings are downstream: grouping and output are skipped when the strings are unchanged. That is a big improvement, but generation cost is still O(tests) per keystroke. A comment or a follow-up could note this. Gating on a cheaper per-file signal, such as the syntax tree and the base-type or attribute closure, could remove the remaining cost later.
2. Silent skips. GetSemanticModel returns null when !compilation.ContainsSyntaxTree, and GenerateTestMethod then returns null with no diagnostic. That state should be unreachable, but if it ever happens the test is silently not generated. Consider a debug assertion or a TUNIT0999 diagnostic.
3. _lastSemanticModel cache. The unsynchronized field is safe as commented, because it is read into a local and its tree is checked before use. The saving relies on methods arriving grouped by syntax tree, which the incremental engine doesn't guarantee. If ordering changes, the cost is extra GetSemanticModel calls, not incorrect output. Roslyn already caches semantic models per compilation, so measure whether this field earns its complexity.
4. Per-compilation state. ConditionalWeakTable<Compilation, GenerationState> is created inside Initialize. It ties the state's lifetime to the compilation, which avoids leaks. Add a short note that GenerationState must never be captured by any model that flows through the pipeline, since that would reintroduce the retention bug this PR fixes.

Nice cleanup overall. Approving in spirit.

[greptile-apps]

Confidence Score: 5/5

[High risk] Refactors test metadata generation pipeline for incremental caching.

The PR appears safe to merge; no outstanding findings remain.

Summary

This PR makes test-generation results equatable so unchanged generated sources can be reused across compilations, and moves incrementality tests into the CI-run source-generator test project. The only change since the previous review shares the existing error descriptor.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Test and InheritsTests declarations] --> B[Current-compilation generation]
  B --> C[Equatable string-only results]
  C --> D[Per-class grouping or standalone sources]
  D --> E[Generated output]

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_{Reviews (4) · Last reviewed commit: "refactor(source-gen): hoist TUNIT0999 de..."}

[github-actions]

Review of #6918

I reviewed the pipeline change in TestMetadataGenerator.cs and the new string-only models. The Claude Code review skill errored, so this is a manual read. I did not build the branch or run any tests.

What looks good

• The pipeline now carries only equatable values: a declaration node, then Combine with the enabled flag and CompilationProvider, then a string-only TestMethodGenerationResult. That removes the symbol and GeneratorAttributeSyntaxContext retention that made every compilation mark every test Modified.
• TestGenerationError keeps its span and path instead of a Location, so no syntax tree stays alive.
• EnableTUnitSourceGeneration=false builds still skip all symbol work. I checked this by reading the code: the enabled flag is checked before GenerateTestMethod runs.
• The per-compilation GenerationState in a ConditionalWeakTable is reasonable. The unsynchronized _lastSemanticModel is safe because it is read into a local and its SyntaxTree is checked before use.
• TestMetadataIncrementalTests adds tracking-name coverage. Deleting the unused ITestAnalyzer and TestMethodAnalyzer is fine.

Concerns

1. The generation Select now re-runs for every test on every compilation. Combine(CompilationProvider) means an edit anywhere, including a whitespace change, re-runs GenerateTestMethod and GenerateInheritedTests for all tests and regenerates each test's code strings. Only the downstream grouping and output steps are cached. Before this change the transform only re-ran for changed syntax trees, but its output was never cacheable. In an IDE with many thousands of tests, the per-keystroke cost of this Select could match or exceed the savings. The PR reports the identical-output hash but no before and after timings for an incremental edit. AGENTS.md asks for measurements on performance changes, so please add:
   • a benchmark of one edit in an unrelated file on a large synthetic project;
   • the wall time of the Select step, with cache-hit counts;
   • optionally, a cheaper per-test fingerprint (for example, hashing the attribute and signature data) that gates the expensive string generation, so unchanged tests skip codegen.
2. The Where(result is not null) steps and the null-returning Selects are a mild smell. A null result caches as a real value, and the ! suppressions at the call sites hide that. This is minor.
3. Combine(enabledProvider) on every node adds a join. Applying the enabled flag once, for example by short-circuiting the provider, would be simpler. This is minor.
4. Test gap. The tests should confirm that editing one test's body or attributes re-emits only that class's file. They should also cover a change in a base class affecting an [InheritsTests] result, because that dependency is now only implicit through the compilation.

Overall the caching design is sound and the output is reported unchanged. My main ask is measured evidence for concern 1 before merge.

[thomhurst]

Responses to the github-actions reviews:

• Every compilation still regenerates every test's strings / per-keystroke cost: yes, intentionally. A test's output depends on symbols in other files, so the step has to re-run. The attribute transform on main also re-ran every compilation, so this cost isn't new. What changes is that the output is now equatable, so grouping and output are cached. Before/after timings for an unrelated edit and for a test edit (20k tests, median of 15) are in the PR description's Timing section: slightly faster in both cases, and 1,201 generated files are no longer re-added. A cheaper per-test fingerprint could remove the remaining cost, but that's a larger follow-up.
• Silent skip when the tree isn't in the compilation: that can't happen, because the node comes from this compilation's own attribute pipeline. It's a guard against an ArgumentException. A comment now says so (e2ae23f).
• GenerationState must not be captured by pipeline values: added to its doc comment (e2ae23f).
• _lastSemanticModel race: already commented as benign. A race only costs an extra GetSemanticModel call.
• Test gaps: already covered in TestMetadataIncrementalTests. Renaming one test makes only that class's group Modified, and renaming a base-class test makes the [InheritsTests] result Modified.
• Null results / the Combine(enabled) join: left as is. A null result caches like any other value. The enabled join is what keeps reflection-mode builds from doing symbol work.

[github-actions]

Review

Solid change. The pipeline now carries only equatable, string-based values (TestMethodGenerationResult, EquatableArray) instead of symbols and GeneratorAttributeSyntaxContext. That fixes the root cause: symbols from a new compilation never compare equal, so every step was marked Modified. The tracking names and the incremental tests make the caching behaviour checkable. The PR also reports unchanged snapshots and matching output hashes on a 20k-test project.

Design notes (none blocking):

1. Per-keystroke cost. Combine(CompilationProvider).Select(...) re-runs symbol resolution and code generation for every test on every compilation. It is now cheap downstream, but the generation itself is still O(tests) per edit. That is inherent because tests depend on symbols in other files, and the PR comment says so. If it shows up in IDE profiling later, a cheaper syntax-level fingerprint could gate the expensive work. I would not do that here.
2. GenerationState._lastSemanticModel. The unsynchronized cache is safe as commented, since the tree is checked before use. It relies on tests arriving grouped by syntax tree. That is only an optimisation, so correctness is unaffected.
3. TUNIT0999 descriptor. The DiagnosticDescriptor is built on each emit. Hoisting it to a static readonly field would be tidier and avoids repeated allocation. It only happens on the error path, so this is minor.
4. Deletions. The PR removes GenericTypeHelper, HookLocationType, and others. Please confirm nothing else references them. HookLocationType is public, so it also needs a check against tests/TUnit.PublicAPI.

I found no correctness issues. Approving in spirit.

[thomhurst]

Thanks for the review. Going through each point:

1. Per-keystroke O(tests) cost: no change. As noted earlier, per-method work is only re-run for methods whose syntax or semantic inputs changed; the remaining per-keystroke cost is the equality comparison over the cached results, which is cheap compared with regenerating source.

2. GenerationState._lastSemanticModel: no change. The cache is only a fast path. Each GenerationState is scoped to one compilation, and the worst case under concurrent access is a cache miss followed by a fresh GetSemanticModel call for the same tree, so it is always correct.

3. TUNIT0999 descriptor: fixed in d97de45. It is now a static readonly DiagnosticDescriptor field instead of being built on every emit.

4. Removed types: I searched the repo (src, tests, and PublicAPI snapshots) and found nothing that still references HookLocationType, ITestAnalyzer, TestMethodAnalyzer, DataSourceModel, TestMethodModel, HooksDataModel, TestDescriptorModel, or TestMetadataGenerationContext. The only remaining GenericTypeHelper hits are for TUnit.Core.Helpers.GenericTypeHelper, which is a separate runtime type that the generated code calls, and it is unchanged. HookLocationType was declared public, but only inside TUnit.Core.SourceGenerator, which has IsPackable=false and ships only as an analyzer. Consumers never get it as a compile reference, and tests/TUnit.PublicAPI doesn't cover that assembly, so there's no public API impact and no snapshot changes.

TUnit.Core.SourceGenerator.Tests (net10.0): 160 passed, 1 skipped (the existing skip), 0 failed.