perf: AbstractTestClassWithDataSourcesAnalyzer scans all types globally

[thomhurst]

Description

File: TUnit.Analyzers/AbstractTestClassWithDataSourcesAnalyzer.cs (Lines 107, 153-175)

var allTypes = GetAllNamedTypes(context.Compilation.GlobalNamespace);

This recursively walks every type in the entire compilation (including all referenced assemblies) every time an abstract type is analyzed. This is O(n) per abstract test class.

Additionally, data source detection (lines 63-79) uses fragile string-contains checks:

if (typeName.Contains("DataSource") || typeName == "ArgumentsAttribute")

Custom data sources without "DataSource" in the name will be missed.

Suggested Fix

• Cache the type hierarchy or restrict search to the current assembly
• Rely on the interface check (IDataSourceAttribute) instead of string-based matching

[claude]

Analysis

Type: Performance improvement + correctness bug

Priority: Medium

Performance concern

GetAllNamedTypes recursively walks the entire compilation (including referenced assemblies) on every invocation for each abstract test class analyzed. In large solutions this becomes O(n × m) where n = number of abstract test classes and m = all named types in the compilation. Caching the type set per compilation context (e.g., using CompilationAnalysisContext or a ConditionalWeakTable) or restricting the search to the current assembly would eliminate the redundant work.

Correctness bug

The string-based data source detection (typeName.Contains("DataSource") || typeName == "ArgumentsAttribute") is fragile and will silently miss valid custom data sources whose names don't follow the convention. This is the same root fragility that manifested as #4812 (false TUnit0001 on custom generic IDataSourceAttribute). Switching to an interface-based check (IDataSourceAttribute symbol check via ITypeSymbol.AllInterfaces) would make detection both correct and convention-independent.

Labels added

• enhancement (already present) — for the perf improvement
• bug — for the string-matching correctness issue

Related

• [Bug]: TUnit0001 raised on custom generic data source attributes #4812 (closed) — a symptom of the same fragile string-based detection logic