Implement TestCultureAttribute

src/Adapter/MSTest.TestAdapter/Execution/TestMethodInfo.cs

@@ -43,6 +43,7 @@ internal TestMethodInfo(
         TestMethod = testMethod;
         Parent = parent;
         TestMethodOptions = testMethodOptions;
+        TestCultureName = GetAttributes<TestCultureAttribute>(inherit: false).FirstOrDefault()?.CultureName;
     }
 
     /// <summary>
@@ -87,6 +88,8 @@ internal TestMethodInfo(
     /// </summary>
     internal TestMethodOptions TestMethodOptions { get; }
 
+    internal string? TestCultureName { get; }
+
     public Attribute[]? GetAllAttributes(bool inherit) => ReflectHelper.Instance.GetDerivedAttributes<Attribute>(TestMethod, inherit).ToArray();
 
     public TAttributeType[] GetAttributes<TAttributeType>(bool inherit)

src/TestFramework/TestFramework.Extensions/Attributes/UWP_UITestMethodAttribute.cs

@@ -33,7 +33,13 @@ public override TestResult[] Execute(ITestMethod testMethod)
         TestResult? result = null;
         Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(
             Windows.UI.Core.CoreDispatcherPriority.Normal,
-            () => result = testMethod.Invoke(null)).AsTask().GetAwaiter().GetResult();
+            () =>
+            {
+                using (SetCultureForTest(testMethod))
+                {
+                    result = testMethod.Invoke(null);
+                }
+            }).AsTask().GetAwaiter().GetResult();
 
         return [result!];
     }

src/TestFramework/TestFramework/Attributes/TestMethod/TestCultureAttribute.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.VisualStudio.TestTools.UnitTesting;
+
+/// <summary>
+/// Attribute to specify the CultureInfo.CurrentCulture and CultureInfo.CurrentUICulture when running the test.
+/// </summary>
+[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
+public sealed class TestCultureAttribute : Attribute
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TestCultureAttribute"/> class.
+    /// </summary>
+    /// <param name="cultureName">
+    /// The culture to be used for the test. For example, "en-US".
+    /// </param>
+    public TestCultureAttribute(string cultureName) => CultureName = cultureName;
+
+    /// <summary>
+    /// Gets the owner.
+    /// </summary>
+    public string CultureName { get; }
+}

src/TestFramework/TestFramework/Attributes/TestMethod/TestMethodAttribute.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Globalization;
+
 namespace Microsoft.VisualStudio.TestTools.UnitTesting;
 
 /// <summary>
@@ -9,6 +11,29 @@ namespace Microsoft.VisualStudio.TestTools.UnitTesting;
 [AttributeUsage(AttributeTargets.Method)]
 public class TestMethodAttribute : Attribute
 {
+    private protected readonly struct ScopedCultureDisposable : IDisposable
+    {
+        private readonly CultureInfo _previousCulture;
+        private readonly CultureInfo _previousUICulture;
+
+        public ScopedCultureDisposable(string cultureName)
+        {
+            _previousCulture = CultureInfo.CurrentCulture;
+            _previousUICulture = CultureInfo.CurrentUICulture;
+
+            var newCulture = new CultureInfo(cultureName);
+            // TODO: Should we set both? Should we have different attribute? Same attribute with two arguments?
+            CultureInfo.CurrentCulture = newCulture;
+            CultureInfo.CurrentUICulture = newCulture;
+        }
+
+        public void Dispose()
+        {
+            CultureInfo.CurrentCulture = _previousCulture;
+            CultureInfo.CurrentUICulture = _previousUICulture;
+        }
+    }
+
     /// <summary>
     /// Initializes a new instance of the <see cref="TestMethodAttribute"/> class.
     /// </summary>
@@ -36,5 +61,19 @@ public TestMethodAttribute()
     /// <param name="testMethod">The test method to execute.</param>
     /// <returns>An array of TestResult objects that represent the outcome(s) of the test.</returns>
     /// <remarks>Extensions can override this method to customize running a TestMethod.</remarks>
-    public virtual TestResult[] Execute(ITestMethod testMethod) => [testMethod.Invoke(null)];
+    public virtual TestResult[] Execute(ITestMethod testMethod)
+    {
+        using (SetCultureForTest(testMethod))
+        {
+            return [testMethod.Invoke(null)];
+        }
+    }
+
+    // TestMethodInfo isn't accessible here :/
+    // Can we add TestCultureName to the *public* interface?
+    // Or should we introduce an internal interface ITestMethod2 : ITestMethod :/
+    private protected static ScopedCultureDisposable? SetCultureForTest(ITestMethod testMethod)
+        => testMethod is TestMethodInfo testMethodInfo && testMethodInfo.TestCultureName is { } culture
+            ? new ScopedCultureDisposable(culture)
+            : (ScopedCultureDisposable?)null;
 }

src/TestFramework/TestFramework/PublicAPI/PublicAPI.Unshipped.txt

@@ -1 +1,4 @@
 #nullable enable
+Microsoft.VisualStudio.TestTools.UnitTesting.TestCultureAttribute
+Microsoft.VisualStudio.TestTools.UnitTesting.TestCultureAttribute.CultureName.get -> string!
+Microsoft.VisualStudio.TestTools.UnitTesting.TestCultureAttribute.TestCultureAttribute(string! cultureName) -> void