Merge pull request #85 from bacathey/Fix_Directory_GetFiles_NullReferenceException_behavior

Fixed NullReferenceException behavior in MockDirectory.GetFiles

Author: tathamoddie

TestHelpers.Tests/MockDirectoryTests.cs

@@ -504,6 +504,15 @@ public void MockDirectory_GetFileSystemEntries_Returns_Files_And_Directories()
             Assert.AreEqual(testPath, entries.First());
         }
 
+        [Test]
+        public void MockDirectory_GetFiles_ShouldThrowArgumentNullException_IfPathParamIsNull()
+        {
+            var fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+
+            TestDelegate action = () => fileSystem.Directory.GetFiles(null);
+            Assert.Throws<ArgumentNullException>(action);
+        }
+
         [Test]
         public void MockDirectory_GetFiles_ShouldThrowDirectoryNotFoundException_IfPathDoesNotExists()
         {

TestingHelpers/MockDirectory.cs

@@ -156,6 +156,9 @@ public override string[] GetFiles(string path, string searchPattern)
 
         public override string[] GetFiles(string path, string searchPattern, SearchOption searchOption)
         {
+            if(path == null)
+                throw new ArgumentNullException();
+
             if (!Exists(path))
             {
                 throw new DirectoryNotFoundException(string.Format(CultureInfo.InvariantCulture, "Could not find a part of the path '{0}'.", path));