Implement UseCultureAttribute

This is necessary to make sure all tests use en-US to get standard texts
without explicitly specifying the culture every time the resource file is
accessed.

The code for this class was taken from the xunit/sample.xunit repository
which is (c) 2014 Outercurve Foundation and licensed under the Apache License,
Version 2.0.

Author: Christian Käser

StyleCop.Analyzers/StyleCop.Analyzers.Test/Helpers/UseCultureAttribute.cs

@@ -0,0 +1,103 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+namespace StyleCop.Analyzers.Test.Helpers
+{
+    using System;
+    using System.Globalization;
+    using System.Reflection;
+    using System.Threading;
+
+    using Xunit.Sdk;
+
+    /// <summary>
+    /// Apply this attribute to your test method to replace the
+    /// <see cref="Thread.CurrentThread" /> <see cref="CultureInfo.CurrentCulture" /> and
+    /// <see cref="CultureInfo.CurrentUICulture" /> with another culture.
+    /// </summary>
+    /// <remarks>
+    /// This code was adapted from
+    /// https://github.com/xunit/samples.xunit/blob/885edfc/UseCulture/UseCultureAttribute.cs.
+    /// The original code is (c) 2014 Outercurve Foundation and licensed under the Apache License,
+    /// Version 2.0.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
+    public class UseCultureAttribute : BeforeAfterTestAttribute
+    {
+        private readonly Lazy<CultureInfo> culture;
+
+#pragma warning disable SA1305
+        private readonly Lazy<CultureInfo> uiCulture;
+#pragma warning restore SA1305
+
+        private CultureInfo originalCulture;
+
+        private CultureInfo originalUiCulture;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UseCultureAttribute"/>
+        /// class with a culture.
+        /// </summary>
+        /// <param name="culture">The name of the culture.</param>
+        /// <remarks>
+        /// <para>
+        /// This constructor overload uses <paramref name="culture" /> for both
+        /// <see cref="Culture" /> and <see cref="UiCulture" />.
+        /// </para>
+        /// </remarks>
+        public UseCultureAttribute(string culture)
+            : this(culture, culture)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UseCultureAttribute"/>
+        /// class with a culture and a UI culture.
+        /// </summary>
+        /// <param name="culture">The name of the culture.</param>
+        /// <param name="uiCulture">The name of the UI culture.</param>
+        public UseCultureAttribute(string culture, string uiCulture)
+        {
+            this.culture = new Lazy<CultureInfo>(() => new CultureInfo(culture));
+            this.uiCulture = new Lazy<CultureInfo>(() => new CultureInfo(uiCulture));
+        }
+
+        /// <summary>
+        /// Gets the culture.
+        /// </summary>
+        /// <value>The culture.</value>
+        public CultureInfo Culture => this.culture.Value;
+
+        /// <summary>
+        /// Gets the UI culture.
+        /// </summary>
+        /// <value>The UI culture.</value>
+        public CultureInfo UiCulture => this.uiCulture.Value;
+
+        /// <summary>
+        /// Stores the current <see cref="Thread.CurrentPrincipal" />
+        /// <see cref="CultureInfo.CurrentCulture" /> and <see cref="CultureInfo.CurrentUICulture" />
+        /// and replaces them with the new cultures defined in the constructor.
+        /// </summary>
+        /// <param name="methodUnderTest">The method under test</param>
+        public override void Before(MethodInfo methodUnderTest)
+        {
+            this.originalCulture = Thread.CurrentThread.CurrentCulture;
+            this.originalUiCulture = Thread.CurrentThread.CurrentUICulture;
+
+            Thread.CurrentThread.CurrentCulture = this.Culture;
+            Thread.CurrentThread.CurrentUICulture = this.UiCulture;
+        }
+
+        /// <summary>
+        /// Restores the original <see cref="CultureInfo.CurrentCulture" /> and
+        /// <see cref="CultureInfo.CurrentUICulture" /> to <see cref="Thread.CurrentPrincipal" />
+        /// </summary>
+        /// <param name="methodUnderTest">The method under test</param>
+        public override void After(MethodInfo methodUnderTest)
+        {
+            Thread.CurrentThread.CurrentCulture = this.originalCulture;
+            Thread.CurrentThread.CurrentUICulture = this.originalUiCulture;
+        }
+    }
+}

StyleCop.Analyzers/StyleCop.Analyzers.Test/StyleCop.Analyzers.Test.csproj

@@ -180,6 +180,7 @@
     <Compile Include="Helpers\MetadataReferences.cs" />
     <Compile Include="Helpers\TestDiagnosticProvider.cs" />
     <Compile Include="Helpers\TestXmlReferenceResolver.cs" />
+    <Compile Include="Helpers\UseCultureAttribute.cs" />
     <Compile Include="HelperTests\AccessLevelHelperTests.cs" />
     <Compile Include="HelperTests\IndentationHelperTests.cs" />
     <Compile Include="HelperTests\TokenHelperTests.cs" />