Tests now use correct path style on Windows vs Unix.

Author: tintoy

test/Client.Tests/ClientTests.cs

@@ -32,7 +32,7 @@ public ClientTests(ITestOutputHelper testOutput)
         /// <summary>
         ///     Get an absolute document path for use in tests.
         /// </summary>
-        string AbsoluteDocumentPath => Path.DirectorySeparatorChar + "Foo.txt"; // Absolute path, cross-platform compatible.
+        string AbsoluteDocumentPath => IsWindows ? @"C:\Foo.txt" : "/Foo.txt";
 
         /// <summary>
         ///     The <see cref="LanguageClient"/> under test.
@@ -141,4 +141,4 @@ void HandleServerInitialize()
             });
         }
     }
-}
+}

test/Client.Tests/TestBase.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Reactive.Disposables;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Threading;
 using Xunit;
 using Xunit.Abstractions;
@@ -124,5 +125,15 @@ protected virtual void Dispose(bool disposing)
         ///     The logging level for the current test.
         /// </summary>
         protected virtual LogLevel LogLevel => LogLevel.Information;
+
+        /// <summary>
+        ///     Is the test running on Windows?
+        /// </summary>
+        protected virtual bool IsWindows => RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+
+        /// <summary>
+        ///     Is the test running on a Unix-like operating system?
+        /// </summary>
+        protected virtual bool IsUnix => RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
     }
 }