public void Replace3() { string tempFile = Path.Combine(Path.GetTempPath(), "OriginalFile.txt"); string tempFile2 = Path.Combine(Path.GetTempPath(), "NewFile.txt"); string backupFile = Path.Combine(Path.GetTempPath(), "OriginalFileBackup.txt"); string expected = "This is a test."; File.Delete(tempFile); File.Delete(tempFile2); File.Delete(backupFile); File.AppendAllText(tempFile, expected); File.AppendAllText(tempFile2, String.Empty); // Move the contents of tempFile into tempFile2 ExtendedFileInfo efi = new ExtendedFileInfo(tempFile); efi.Replace(tempFile2, backupFile, true); Assert.IsTrue(File.Exists(backupFile)); Assert.IsTrue(File.Exists(tempFile2)); string actual = File.ReadAllText(tempFile2); Assert.AreEqual(expected, actual); }