Update description in Readme

Author: chriswalpen

README.md

@@ -4,3 +4,37 @@ Abstraction for the .Net Filesystem classes
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+
+Wrappers for some common classes from System.IO Namespace to create a layer of abstraction
+
+Current implementaitons of System.IO
+* Directory
+* File
+
+## Usage in code
+Instead of using the Namespace System.IO include the Namespace Abstract.FileSystem to use Directory or File.
+
+## Usage in Tests
+Abstract.FileSystem.Directory and Abstract.FileSystem.File both have a Factory Property. This can be set through the static method Setup(Func<IFileService> service) or Setup(Func<IDirectoryService> service).
+The Interface IFileService and IDirectoryService both provide the abstraction layers.
+
+```
+_service = new Mock<IDirectoryService>();
+Directory.Setup(() => _service.Object);
+```
+Now all Access to Abstract.FileSystem.Directory use the Mock of IDirectoryServerice
+
+# SystemPath
+Path behaviour on Linux differs from Windows. For this reason there is a class for SystemPath that manages paths depending on the system that is run on.
+```
+var path = (SystemPath)"Test" / "Path";
+path.ToString();
+```
+On a Windows this results in
+```
+Test\Path
+```
+while on a Unix system the result looks different
+```
+Test/Path
+```