Updated test to (hopfully) also work on linux machines

Author: Jens Weiermann

System.IO.Abstractions.TestingHelpers.Tests/DirectoryInfoTests.cs

@@ -13,8 +13,9 @@ public void Parent_ForRootDirectory_ShouldReturnNull()
         {
             var wrapperFilesystem = new FileSystem();
 
-            var directoryInfo = wrapperFilesystem.DirectoryInfo.FromDirectoryName("C:\\");
-            var rootsParent = directoryInfo.Parent;
+            var current = wrapperFilesystem.Directory.GetCurrentDirectory();
+            var root = wrapperFilesystem.DirectoryInfo.FromDirectoryName(current).Root;
+            var rootsParent = root.Parent;
             Assert.IsNull(rootsParent);
         }
     }

System.IO.Abstractions/DirectoryInfoWrapper.cs

@@ -230,9 +230,13 @@ public override DirectoryInfoBase Parent
             get
             {
                 if (instance.Parent == null)
+                {
                     return null;
+                }
                 else
+                {
                     return new DirectoryInfoWrapper(FileSystem, instance.Parent);
+                }
             }
         }