perf(engine): reduce allocations in reflection-mode discovery/execution by thomhurst · Pull Request #6113 · thomhurst/TUnit (original) (raw)

Cuts per-call/per-method/per-test allocations on the reflection runtime fallback path (no behaviour change):

• IsCovariantCompatible: hoist the covariant-interface list to a static readonly array and check argType separately instead of Concat([argType]).ToArray() per call.
• ReflectionMetadataBuilder / ReflectionHookDiscoveryService: replace GetParameters().Select(...).ToArray() with manual loops into a pre-sized ParameterMetadata[].
• ReflectionHookDiscoveryService hook ordering: pre-compute (minOrder, metadataToken) sort keys into a struct array and Array.Sort instead of an OrderBy lambda that allocated a List and recomputed attributes per comparison. (order, token) is a total key so order semantics are preserved.
• PropertyInjector caching paths: resolve the injected-arguments dictionary once and reuse it for the early-out guard and the add, collapsing the redundant ContainsKey-property + GetOrCreate lookups. Injection guard logic unchanged.
• ConstructorHelper: foreach+break instead of Where().ToArray() to find the [TestConstructor]-marked ctor.
• ReflectionTestDataCollector: unify the ReflectionTypeLoadException fallback onto the shared ArrayPool streaming filter; add StringComparison.Ordinal to ShouldScanAssembly comparisons.
• TestDiscoveryService: project tests onto a pre-sized List instead of allTests.Select(t => t.Context).

Closes #6105

[](/apps/claude)

• Consolidate the two diverging reflection BuildParameterMetadata impls (ReflectionMetadataBuilder + ReflectionHookDiscoveryService) into a shared ParameterMetadataFactory. Behavioural differences (name fallback, IsNullable computation, AOT RequiresUnreferencedCode) are preserved via explicit parameters so observable output is unchanged.
• Collapse BuildParameterMetadata / BuildConstructorParameterMetadata into the single factory entry with a nameFallback parameter (null => "param{index}", "unnamed" for methods).
• PropertyInjector: restore the cheap early-out in the two ResolveAndCache* caching paths. The perf pass eagerly called GetOrCreateInjectedPropertyArguments() upfront, materialising the per-test dictionary even when the property resolved to null. Now read the empty read-only singleton via the public property for the ContainsKey guard and only create the dictionary when actually storing a value.
• TestDiscoveryService.ToContextList: make the comment honest by explaining the actual win — TestDiscoveryContext.AddTests stores an IReadOnlyList directly and only ToArray()s otherwise, so passing a pre-sized List avoids the Select enumerator + ToArray copy.

[](/apps/claude)

thomhurst deleted the perf/issue-6105-reflection-allocs branch

May 28, 2026 23:29

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May 29, 2026

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Jun 14, 2026

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