fix(mocks): CS9262 in generated mock members on VS 17.14 (Roslyn 4.14)

[thomhurst]

Summary

Fixes #6370 — since v1.44.0, any Type.Mock() usage failed to compile under Visual Studio 17.14 with:

CS9262: Cannot use 'OverloadResolutionPriorityAttribute' on this member. (×3)

Root cause

The *_MockMembers.g.cs polyfills introduced in #5881 apply [OverloadResolutionPriority(-1)] to the three extension-block properties (Invocations, Behavior, DefaultValueProvider) — hence exactly three errors. Roslyn 4.14 (VS 17.14) rejects the attribute on non-indexer extension properties with CS9262; the Roslyn shipped with the .NET 10 SDK accepts it, which is why CI and local builds never caught it.

Fix

Remove the attribute from the property polyfills only. It was inert there: the polyfill is skipped whenever the mocked type declares a member of the same name, so no same-name member can coexist in the containing type for the attribute to rank against. Method polyfills keep it — the attribute is legal on ordinary static methods since Roslyn 4.12.

Testing

• TUnit.Mocks.SourceGenerator.Tests: 76/76 pass; all 58 affected snapshots re-verified — every diff is purely the three attribute-line removals.
• TUnit.Mocks.Tests (net10.0): 1158/1158 pass — mock.Invocations / mock.Behavior / mock.DefaultValueProvider ergonomics unchanged.
• CS9262 itself is not reproducible in-repo (test infra compiles with latest Roslyn, which permits the attribute); the snapshots are the regression guard, with a code comment explaining the constraint.

[codacy-production]

Up to standards ✅

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[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

Summary: This is a narrowly-scoped fix for #6370 (CS9262 under VS 17.14/Roslyn 4.14). MockMembersBuilder.cs stops emitting [OverloadResolutionPriority(-1)] on the three extension-block property polyfills (Invocations, Behavior, DefaultValueProvider), since Roslyn 4.14 rejects that attribute on non-indexer extension properties. Method polyfills correctly retain the attribute. The 58 updated .verified.txt snapshots match the generator change one-for-one, with no .received.txt files committed.

Verified independently:

• The "attribute was inert on properties" claim holds — each property polyfill is only emitted when the mocked type has no same-name member (emitInvocations = !userNames.Contains("Invocations"), etc.), so there's never a competing candidate for the priority to rank against, and properties can't be overloaded anyway.
• No dual-mode (source-gen vs reflection) concern — mocking has no reflection-mode counterpart to keep in sync.
• No .received.txt files, no VSTest references, no AOT/perf-sensitive surface touched.

🤖 Generated with automated code review