Throw DirectoryNotFoundException when try open FileStream in non-existing path.

Author: PatrykOlejniczak

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

@@ -3,6 +3,8 @@
 
 namespace System.IO.Abstractions.TestingHelpers.Tests
 {
+    using XFS = MockUnixSupport;
+
     [TestFixture]
     public class MockFileStreamFactoryTests
     {
@@ -41,5 +43,21 @@ public void MockFileStreamFactory_CreateForNonExistingFile_ShouldReturnStream(Fi
             // Assert
             Assert.IsNotNull(result);
         }
+
+        [Test]
+        [TestCase(FileMode.Create)]
+        [TestCase(FileMode.Open)]
+        public void MockFileStreamFactory_CreateInNonExistingDirectory_ShouldThrowDirectoryNotFoundException(FileMode fileMode)
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(XFS.Path(@"C:\Test"));
+
+            // Act
+            var fileStreamFactory = new MockFileStreamFactory(fileSystem);
+
+            // Assert
+            Assert.Throws<DirectoryNotFoundException>(() => fileStreamFactory.Create(@"C:\Test\NonExistingDirectory\some_random_file.txt", fileMode));
+        }
     }
 }

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

@@ -13,16 +13,18 @@ public class MockFileStreamTests
         public void MockFileStream_Flush_WritesByteToFile()
         {
             // Arrange
-            var filepath = XFS.Path(@"c:\something\foo.txt");
-            var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
-            var cut = new MockFileStream(filesystem, filepath, MockFileStream.StreamType.WRITE);
+            var filepath = XFS.Path(@"C:\something\foo.txt");
+            var fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            fileSystem.AddFile(@"C:\something\foo.txt", new MockFileData(""));
+
+            var cut = new MockFileStream(fileSystem, filepath, MockFileStream.StreamType.WRITE);
 
             // Act
             cut.WriteByte(255);
             cut.Flush();
 
             // Assert
-            CollectionAssert.AreEqual(new byte[]{255}, filesystem.GetFile(filepath).Contents);
+            CollectionAssert.AreEqual(new byte[]{255}, fileSystem.GetFile(filepath).Contents);
         }
 
         [Test]
@@ -52,10 +54,11 @@ public void MockFileStream_Constructor_Reading_Nonexistent_File_Throws_Exception
         {
             // Arrange
             var nonexistentFilePath = XFS.Path(@"c:\something\foo.txt");
-            var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            var fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            fileSystem.AddDirectory(XFS.Path(@"C:\something"));
 
             // Act
-            Assert.Throws<FileNotFoundException>(() => new MockFileStream(filesystem, nonexistentFilePath, MockFileStream.StreamType.READ));
+            Assert.Throws<FileNotFoundException>(() => new MockFileStream(fileSystem, nonexistentFilePath, MockFileStream.StreamType.READ));
 
             // Assert - expect an exception
         }

System.IO.Abstractions.TestingHelpers/MockFileStream.cs

@@ -57,10 +57,16 @@ public MockFileStream(
             }
             else
             {
+                if (!mockFileDataAccessor.Directory.Exists(Path.GetDirectoryName(path)))
+                {
+                    throw CommonExceptions.CouldNotFindPartOfPath(path);
+                }
+
                 if (StreamType.READ.Equals(streamType))
                 {
                     throw CommonExceptions.FileNotFound(path);
                 }
+
                 mockFileDataAccessor.AddFile(path, new MockFileData(new byte[] { }));
             }