public void GetAllTextFiles() { var fileViewer = new FileViewer(_fileSystem); var files = fileViewer.GetAllTextFiles(_tree); var tree = new DirectoryTree(_tree); tree.Files.Add(@"c:\myfile.txt"); tree.Files.Add(@"c:\anotherfile.txt"); tree.SubDirectories[1].Files.Add(@"c:\demo\sample.txt"); Assert.AreEqual(tree, files); }