[code-simplifier] Simplify ExecutableConditionAttribute code

[Evangelink]

Code Simplification — 2026-06-23

This PR simplifies ExecutableConditionAttribute, added in #9369, to improve clarity and consistency while preserving all functionality.

Files Simplified

• src/TestFramework/TestFramework/Attributes/TestMethod/ExecutableConditionAttribute.cs — three targeted cleanups

Improvements Made

1. Replaced ternary-throw with explicit null guard

   The original ternary-throw pattern is syntactically valid but reads in an unusual order (the "throw" branch precedes the normal path):

   // Before
   _arguments = arguments is null
       ? throw new ArgumentNullException(nameof(arguments))
       : (string[])arguments.Clone();
   
   // After
   if (arguments is null)
   {
       throw new ArgumentNullException(nameof(arguments));
   }
   
   _arguments = (string[])arguments.Clone();

   The explicit guard-then-assign form is more readable and consistent with patterns used elsewhere in the file (e.g. the if (process is null) return false; guard in TryRunWithExitCodeZero).

2. Used string.IsNullOrEmpty for combined null+empty check

   // Before
   if (pathExt is null || pathExt.Length == 0)
   
   // After
   if (string.IsNullOrEmpty(pathExt))

   string.IsNullOrEmpty is the canonical idiom already used throughout the codebase (e.g. CollectionAssert.Subset.cs, StructuredAssertionMessage.cs, Ensure.cs).

3. Replaced manual array construction with collection spread

   // Before
   string[] result = new string[parts.Length + 1];
   result[0] = string.Empty;
   Array.Copy(parts, 0, result, 1, parts.Length);
   return result;
   
   // After
   return [string.Empty, ..parts];

   The spread syntax is already used in the codebase (e.g. MSTestAdapter.PlatformServices) and generates identical IL. With LangVersion preview set project-wide, this is fully supported.

Changes Based On

• Add ExecutableConditionAttribute to conditionally run tests based on tool availability #9369 — Add ExecutableConditionAttribute to conditionally run tests based on tool availability
• Commit efa7e0d — merged 2026-06-23

Testing

• ✅ No functional changes — all three edits are semantically equivalent to the original
• ✅ Existing tests in ExecutableConditionAttributeTests cover all affected code paths
• ⚠️ Full build requires .NET SDK 11.0.x (preview) which CI will supply

Review Focus

Please verify:

• Functionality is preserved (all three changes are equivalent rewrites)
• Changes align with project conventions

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Pull request overview

This PR performs small readability-focused refactors in ExecutableConditionAttribute (MSTest TestFramework) while preserving behavior, primarily around argument cloning and Windows PATHEXT handling.

Changes:

• Replaced a ternary-throw assignment with an explicit arguments is null guard and subsequent clone.
• Simplified the PATHEXT null/empty check via string.IsNullOrEmpty.
• Simplified the executable-extension array construction using a collection expression with spread.

Show a summary per file

File	Description
src/TestFramework/TestFramework/Attributes/TestMethod/ExecutableConditionAttribute.cs	Refactors constructor argument guarding/cloning and streamlines Windows PATHEXT parsing/extension list construction without changing behavior.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0

[Evangelink]

🔍 Build Failure Analysis

Summary — The build fails due to a single IDE0055 formatting violation in the newly-added return [string.Empty, ..parts] collection-expression spread: the repository style requires a space after .., but the PR omits it.

Root cause: Missing space in collection-expression spread element

IDE0055 ("Fix formatting") is triggered by the Roslyn formatter at line 340, column 33 of ExecutableConditionAttribute.cs. Column 33 is exactly the p in ..parts — the formatter wants to insert a space before parts, turning ..parts into .. parts.

This is consistent with:

• .editorconfig: csharp_space_around_binary_operators = before_and_after — Roslyn applies this rule to the .. token in collection-expression spread elements.
• Existing codebase usage: test/Utilities/Microsoft.Testing.TestInfrastructure/TargetFrameworks.cs:25 already uses [.. Net, .. NetFramework] — spread elements always have a space after .. in this repo.

The error fires four times (once per target framework compiled from TestFramework.csproj) and is promoted to an error by TreatWarningsAsErrors=true on CI.

Affected file / error

• src/TestFramework/TestFramework/Attributes/TestMethod/ExecutableConditionAttribute.cs:340 — IDE0055: Fix formatting

Proposed fix

-        return [string.Empty, ..parts];
+        return [string.Empty, .. parts];

You can also let the toolchain fix it automatically:

dotnet format analyzers src/TestFramework/TestFramework/TestFramework.csproj --diagnostics IDE0055

---

Build overview

Field	Value
Result	❌ FAILED
Duration	177.1 s
MSBuild	18.7.0-preview (SDK 11.0.100-preview.5.26227.104)
Projects built	46
Errors	5 (4 × same IDE0055 + final "Build failed.")
Warnings	0
Failed projects	Build.proj, NonWindowsTests.slnf, MSTest.TestAdapter.csproj, TestFramework.csproj

All MSBuild errors (4 unique + 1 summary)

Code	Project	File:Line	Message
IDE0055	TestFramework.csproj	ExecutableConditionAttribute.cs:340:33	Fix formatting
IDE0055	TestFramework.csproj	ExecutableConditionAttribute.cs:340:33	Fix formatting (TFM 2)
IDE0055	TestFramework.csproj	ExecutableConditionAttribute.cs:340:33	Fix formatting (TFM 3)
IDE0055	TestFramework.csproj	ExecutableConditionAttribute.cs:340:33	Fix formatting (TFM 4)

The same diagnostic repeats for each target framework (net462, netstandard2.0, net6.0, net8.0 or similar) because Roslyn is invoked once per TFM.

---

_{🤖 Generated by the Build Failure Analysis workflow using (a href="(dev.azure.com/redacted) · commit 81e36e2}

🤖 Automated content by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Build Failure Analysis workflow. · 775.1 AIC · ⌖ 21.7 AIC · ⊞ 46.9K · [◷]( · ◷)

[Evangelink]

🤖 Automated content by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Build Failure Analysis workflow. · 775.1 AIC · ⌖ 21.7 AIC · ⊞ 46.9K · ◷

[Copilot]

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0 new

[Evangelink]

Note

🤖 Automated review by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

Review: all three changes are semantically equivalent — LGTM

Dimensions checked: Correctness · API Compat · Cross-TFM · Null Safety · Thread Safety · Performance · Resource Safety · PublicAPI / XLF / resx (none changed) · Code Style

---

Change 1 — Null guard refactor (lines 123–133)

_arguments = arguments is null ? throw ... : ... → if (arguments is null) { throw ... } _arguments = ...

✅ Equivalent. Both branches throw ArgumentNullException when arguments is null; the assignment only runs when arguments is not null. No observable difference in semantics, exception type, or stack frame.

---

Change 2 — string.IsNullOrEmpty (line 331)

pathExt is null || pathExt.Length == 0 → string.IsNullOrEmpty(pathExt)

✅ Equivalent. string.IsNullOrEmpty carries [return: NotNullWhen(false)], so the Roslyn null-flow analysis after the guard is identical to the explicit pattern — pathExt is known non-null in the remainder of the method in both forms.

---

Change 3 — Collection spread [string.Empty, .. parts] (lines 338–343)

Manual new string[parts.Length + 1] / result[0] / Array.Copy → return [string.Empty, .. parts]

✅ Equivalent and cross-TFM safe. Collection expressions are a compiler-lowering feature: Roslyn emits the exact same array-allocation + Array.Copy IL when targeting net462 or netstandard2.0. No BCL type unavailable on those targets is required. The project already uses [string.Empty, ".exe", ...] collection expressions in the early-return path of the same method, confirming the pattern compiles correctly across all TFMs. LangVersion preview is confirmed in Directory.Build.props (<LangVersion>preview</LangVersion>).