perf: IReadOnlyList<Artifact> call ToArray

[TimothyMakkison]

Call ToArray instead of ToList, most of the time the underlying collection contains zero items so it will return an empty array.

Before

After

[thomhurst]

Summary

Changes Artifacts property from ToList() to ToArray() to reduce allocations when the collection is empty.

Critical Issues

None found ✅

Suggestions

Consider caching to eliminate repeated allocations:

The Artifacts property is accessed multiple times in hot paths (TUnit.Engine/Extensions/TestExtensions.cs:144,146 calls it twice). Each call allocates a new array/list from the ConcurrentBag.

While ToArray() is better for empty collections (returns cached Array.Empty), both ToArray() and ToList() allocate for non-empty collections on every access.

Consider caching if the bag is immutable after test execution starts. This would eliminate all repeated allocations.

Verdict

✅ APPROVE - The change improves performance for the common case (empty collections).