Fix MockFileSerialization with empty PathVerifier (#522)

Author: darl2ng

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

@@ -0,0 +1,41 @@
+namespace System.IO.Abstractions.TestingHelpers.Tests
+{
+    using NUnit.Framework;
+    using Text;
+    using XFS = MockUnixSupport;
+    [TestFixture]
+    class MockFileSystemSerializationTests
+    {
+        [Test]
+        public void SerializationBytes()
+        {
+            // Arrange
+            string path = XFS.Path(@"c:\something\demo.txt");
+
+            var content = "Hello there!" + Environment.NewLine + "Second line!" + Environment.NewLine;
+            var expected = Encoding.ASCII.GetBytes(content); //Convert a C# string to a byte array
+
+            var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(XFS.Path(@"c:\something"));
+
+            fileSystem.File.WriteAllBytes(path, expected);
+
+            //Act
+            var memoryStream = new MemoryStream();
+            var serializer = new Runtime.Serialization.Formatters.Binary.BinaryFormatter();
+            serializer.Serialize(memoryStream, fileSystem);
+            memoryStream.Flush();
+            memoryStream.Position = 0; 
+            fileSystem = (MockFileSystem)serializer.Deserialize(memoryStream);
+            memoryStream.Dispose();
+
+            // Assert
+            Assert.AreEqual(
+                expected,
+                fileSystem.GetFile(path).Contents);
+            Assert.AreEqual(
+                content,
+                fileSystem.File.ReadAllBytes(path));
+        }
+    }
+}

System.IO.Abstractions.TestingHelpers/MockFileSystem.cs

@@ -13,7 +13,6 @@ public class MockFileSystem : IFileSystem, IMockFileDataAccessor
         private const string DEFAULT_CURRENT_DIRECTORY = @"C:\";
 
         private readonly IDictionary<string, MockFileData> files;
-        [NonSerialized]
         private readonly PathVerifier pathVerifier;
 
         public MockFileSystem() : this(null) { }

System.IO.Abstractions.TestingHelpers/PathVerifier.cs

@@ -4,6 +4,7 @@ namespace System.IO.Abstractions.TestingHelpers
 {
     using XFS = MockUnixSupport;
 
+    [Serializable]
     public class PathVerifier
     {
         private static readonly char[] AdditionalInvalidPathChars = { '*', '?' };