Cache TestMethodIdentifierProperty per TestMethod to avoid redundant parsing

[Evangelink]

Fixes #10363

Problem

MSTestTestNodeConverter.AddTestMethodIdentifier called ManagedNameParser.ParseManagedMethodName and allocated a new TestMethodIdentifierProperty on every node conversion — even though the result is a pure function of TestMethod.ManagedTypeName and TestMethod.ManagedMethodName, both of which are immutable for the lifetime of the instance.

The same TestMethod instance is converted several times per executed test: TestExecutionManager.ExecuteTestsWithTestRunnerAsync reports the original currentTest element to RecordStartAsync (in-progress node) and then to SendTestResultsAsync, which loops over the results and calls RecordResultAsync once per row. So a plain test parses twice, and a data-driven test parses once per data row plus one.

Change

Cache the built property in a static ConditionalWeakTable<TestMethod, TestMethodIdentifierProperty> keyed on the TestMethod instance. Per repeated conversion this removes:

• 1× ParseManagedMethodName call (scans the managed signature, allocates the parameter-type list/array)
• 2× string allocations (the namespace and typeName substrings)
• 1× TestMethodIdentifierProperty allocation

The cache lives in the converter rather than as a lazy property on TestMethod (the way TestMethod.ManagedTypeName caches itself) because TestMethodIdentifierProperty is a Microsoft.Testing.Platform type and MSTestAdapter.PlatformServices does not reference the platform; within MSTest.TestAdapter the platform is only reachable from the TestingPlatformAdapter folder via the file-level RS0030 suppression.

Behavior is unchanged: the null/empty guards are equivalent (HasManagedMethodAndTypeProperties already subsumes the removed IsNullOrEmpty(ManagedMethodName) check), and InvalidManagedNameException still propagates out of the factory with nothing cached, so it is re-thrown identically on the next call.

Safety notes

• Key stability — ManagedMethodName and FullClassName are assigned only in the TestMethod constructor; Clone(), CloneWithSource(), CloneWithUpdatedSource() and the [Serializable] app-domain path all produce new key objects with identical values, so the cache can only miss, never go stale.
• Sharing — every consumer of TestMethodIdentifierProperty (including ParameterTypeFullNames) in src/Platform/** is read-only. That invariant is called out in the XML doc, since the type is not deeply immutable.
• Lifetime — weak keys mean entries disappear as soon as the TestMethod becomes unreachable, so there is no unbounded growth.
• Thread safety — ConditionalWeakTable.GetValue is thread-safe; concurrent misses may each run the factory, but a single value is published.
• The #pragma warning disable IDE0028 is required: a collection expression on ConditionalWeakTable is CS9174 on net462, which lacks IEnumerable<KeyValuePair<,>> on that type.

Tests

Three tests added to MSTestTestNodeConverterTests:

• ToResultTestNode_ReusesTestMethodIdentifier_FromInProgressNode — regression guard; fails without the cache.
• ToDiscoveredTestNode_DoesNotShareTestMethodIdentifier_AcrossDistinctTestMethods — the cache must not conflate two test methods that share a class name.
• ToDiscoveredTestNode_DoesNotAddTestMethodIdentifier_WhenManagedTypeNameIsEmpty — pins the pre-existing empty-ManagedTypeName guard that moved into the fast path.

Full repo build.cmd is clean (0 warnings, 0 errors); MSTestAdapter.UnitTests is 67/67 green on both net9.0 and net462.

Note: the perf claim is based on code inspection (call-path analysis + removed allocations), not a benchmark.

[Copilot]

Pull request overview

Caches parsed MSTest method identifiers during MTP node conversion to reduce repeated parsing and allocations.

Changes:

• Adds a weak per-TestMethod identifier cache.
• Adds regression and cache-isolation tests.

Show a summary per file

File	Description
MSTestTestNodeConverter.cs	Implements identifier caching.
MSTestTestNodeConverterTests.cs	Tests reuse, isolation, and empty type handling.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Balanced

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

Summary

Clean, well-motivated performance optimization. No issues found.

Correctness ✅ — The guard logic is preserved: HasManagedMethodAndTypeProperties already ensures ManagedMethodName is non-null/non-whitespace, and the new StringEx.IsNullOrEmpty(testMethod.ManagedTypeName) check covers the edge case where FullClassName is empty (previously caught by the second null check inside the method). The ! suppressions in BuildTestMethodIdentifier are safe given the caller's pre-validation.

Thread safety ✅ — ConditionalWeakTable.GetValue guarantees a single published value even under concurrent factory execution. No mutable shared state is introduced.

Lifetime / leaks ✅ — Weak keys ensure entries are collected with the TestMethod. No strong reference cycle.

Shared array note — The remarks correctly call out that ParameterTypeFullNames is a shared array. Since all consumers are read-only today this is safe, but worth keeping in mind for future changes.

Tests ✅ — Good coverage: reuse across node types, distinct instances for distinct keys, and the new empty-ManagedTypeName edge case.

No blocking concerns. LGTM.

[github-actions]

🧪 Test quality grade — PR #10366

Grade	Test	Mutation	Notes	How to improve
A (90–100)	new MSTestTestNodeConverterTests. ToDiscoveredTestNode_ DoesNotAddTestMethodIdentifier_ WhenManagedTypeNameIsEmpty	2/2 killed	Precisely targets the new guard condition; absence assertion kills both the missing-clause and wrong-operator mutations.	—
A (90–100)	new MSTestTestNodeConverterTests. ToResultTestNode_ ReusesTestMethodIdentifier_ FromInProgressNode	3/3 killed	BeSameAs reference-identity check directly validates the caching contract and kills any value-equal-but-distinct-instance mutation.	—
A (90–100)	new MSTestTestNodeConverterTests. ToDiscoveredTestNode_ DoesNotShareTestMethodIdentifier_ AcrossDistinctTestMethods	3/3 killed	Five meaningful assertions (NotBeNull ×2, NotBeSameAs, MethodName ×2) collectively guard against cache-key conflation and value-swapping mutations.	—

_{This advisory comment was generated automatically. Grades are heuristic and informational — they do not block merging. Re-run with /grade-tests.}

🤖 Automated content by GitHub Copilot. Generated by the Grade Tests on PR (on open / sync) workflow. · sonnet46 42.7 AIC · ⌖ 4.87 AIC · ⊞ 11.8K · [◷]( · ◷)