Restore [CombinatorialData] in dotnet-watch.Tests using Combinatorial.MSTest

[Evangelink]

Follow-up to #54903.

That PR migrated dotnet-watch.Tests from xUnit to MSTest.Sdk (MTP). As an unwanted side effect, it removed the use of combinatorial test data — every [CombinatorialData] method was replaced with hand-expanded [DataRow(...)] lists, which are verbose and easy to get out of sync with the parameter space.

This PR restores the combinatorial style using Combinatorial.MSTest — the MSTest-native port whose attribute surface ([CombinatorialData], [CombinatorialValues], [CombinatorialRange]) matches Xunit.Combinatorial. This is the same package already consumed by test/dotnet.Tests, and its version flows through central package management (eng/dependabot/Packages.props). The xUnit Xunit.Combinatorial package is left untouched (still used by other projects).

Changes

• dotnet-watch.Tests.csproj: add Combinatorial.MSTest PackageReference and the Combinatorial.MSTest global Using.
• 13 test files: convert the affected methods back from [TestMethod] + explicit [DataRow(...)] lists to [TestMethod, CombinatorialData], restoring [CombinatorialValues(...)] / [CombinatorialRange(...)] parameter attributes where needed and preserving [Ignore] / [OSCondition]:
  • BrowserRefreshServerTests, EvaluationTests, CommandLineOptionsTests, LaunchSettingsTests, FileWatcherTests, AutoRestartTests, BuildParametersSelectionPromptTests, BuildProjectsTests, FileExclusionTests, MauiHotReloadTests, MetadataUpdateHandlerTests, ProjectUpdateTests, RuntimeProcessLauncherTests

All other MSTest migration changes from #54903 (the [TestMethod] attribute, MSTest assertions, lifecycle, etc.) are kept intact. Methods that originally used [InlineData] (now legitimately [DataRow]) are left unchanged.

Validation

dotnet build test/dotnet-watch.Tests/dotnet-watch.Tests.csproj — Build succeeded, 0 warnings, 0 errors.

[Copilot]

Pull request overview

This PR restores combinatorial test coverage in dotnet-watch.Tests after its xUnit → MSTest.Sdk migration by reintroducing [CombinatorialData]-style parameterization using Combinatorial.MSTest (centrally versioned), replacing verbose hand-expanded [DataRow(...)] lists.

Changes:

• Add Combinatorial.MSTest package + global Using to dotnet-watch.Tests.csproj.
• Convert affected MSTest [TestMethod] tests back to [TestMethod, CombinatorialData], using [CombinatorialValues] / [CombinatorialRange] where appropriate.
• Preserve existing [Ignore] / [OSCondition] behavior while restoring combinatorial parameter spaces.

Show a summary per file

File	Description
test/dotnet-watch.Tests/dotnet-watch.Tests.csproj	Adds Combinatorial.MSTest reference and global Using so combinatorial attributes are available project-wide.
test/dotnet-watch.Tests/Browser/BrowserRefreshServerTests.cs	Restores combinatorial coverage for LogLevel × enableHotReload.
test/dotnet-watch.Tests/Build/EvaluationTests.cs	Restores combinatorial coverage for static assets and target framework selection scenarios.
test/dotnet-watch.Tests/CommandLine/CommandLineOptionsTests.cs	Replaces expanded DataRows with combinatorial value sets for options/positions.
test/dotnet-watch.Tests/CommandLine/LaunchSettingsTests.cs	Restores combinatorial boolean coverage for launch profile environment variable behaviors.
test/dotnet-watch.Tests/FileWatcher/FileWatcherTests.cs	Restores combinatorial coverage across polling/nesting/subdirectory watcher permutations.
test/dotnet-watch.Tests/HotReload/AutoRestartTests.cs	Restores combinatorial coverage for interactive/non-interactive restart flows (including ignored test).
test/dotnet-watch.Tests/HotReload/BuildParametersSelectionPromptTests.cs	Uses [CombinatorialRange] to cover selection indices without enumerating [DataRow].
test/dotnet-watch.Tests/HotReload/BuildProjectsTests.cs	Restores combinatorial boolean coverage for file-based app build behaviors.
test/dotnet-watch.Tests/HotReload/FileExclusionTests.cs	Restores full combinatorial coverage for exclusion permutations (existing/included/kind).
test/dotnet-watch.Tests/HotReload/MauiHotReloadTests.cs	Restores combinatorial boolean coverage while keeping OS gating + ignore.
test/dotnet-watch.Tests/HotReload/MetadataUpdateHandlerTests.cs	Restores combinatorial boolean coverage for verbose/non-verbose exception behavior.
test/dotnet-watch.Tests/HotReload/ProjectUpdateTests.cs	Restores combinatorial boolean coverage for Directory.Build.props vs normal project update.
test/dotnet-watch.Tests/HotReload/RuntimeProcessLauncherTests.cs	Restores combinatorial coverage for trigger/update-location enums and boolean shared output.

Copilot's findings

• Files reviewed: 14/14 changed files
• Comments generated: 0

[Evangelink]

/ba-g #54928 and some unrelated trimming issues