Updates the Mock File System to throw DirectoryNotFound if creating a file in a directory that does not exist.

When creating a file in a real file system on Windows, if the filename is in a directory that does not exist, a DirectoryNotFoundException would be thrown. This change, causes the MockFile to behave in the same way.

Additionally some other tests had to be updated. These tests did not tell the mock filesystem that the directory existed before attempting the create.

Author: wleader

TestHelpers.Tests/MockFileCreateTests.cs

@@ -18,6 +18,7 @@ public void Mockfile_Create_ShouldCreateNewStream()
         {
             string fullPath = XFS.Path(@"c:\something\demo.txt");
             var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(@"c:\something");
 
             var sut = new MockFile(fileSystem);
 
@@ -33,6 +34,7 @@ public void Mockfile_Create_CanWriteToNewStream()
         {
             string fullPath = XFS.Path(@"c:\something\demo.txt");
             var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(@"c:\something");
             var data = new UTF8Encoding(false).GetBytes("Test string");
 
             var sut = new MockFile(fileSystem);
@@ -52,6 +54,7 @@ public void Mockfile_Create_OverwritesExistingFile()
         {
             string path = XFS.Path(@"c:\some\file.txt");
             var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(@"c:\some");
 
             var mockFile = new MockFile(fileSystem);
 
@@ -146,5 +149,20 @@ public void MockFile_Create_ShouldThrowArgumentNullExceptionIfPathIsNull()
             var exception = Assert.Throws<ArgumentNullException>(action);
             Assert.That(exception.Message, Does.StartWith("Path cannot be null."));
         }
+
+        [Test]
+        public void MockFile_Create_ShouldThrowDirectoryNotFoundExceptionIfCreatingAndParentPathDoesNotExist()
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+
+            // Act
+            TestDelegate action = () => fileSystem.File.Create("C:\\Path\\NotFound.ext");
+
+            // Assert
+            Assert.IsFalse(fileSystem.Directory.Exists("C:\\path"));
+            var exception = Assert.Throws<DirectoryNotFoundException>(action);
+            Assert.That(exception.Message, Does.StartWith("Could not find a part of the path"));
+        }
     }
 }

TestHelpers.Tests/MockFileOpenTests.cs

@@ -42,6 +42,7 @@ public void MockFile_Open_CreatesNewFileFileOnCreate()
         {
             string filepath = XFS.Path(@"c:\something\doesnt\exist.txt");
             var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            filesystem.AddDirectory(@"c:\something\doesnt");
 
             var stream = filesystem.File.Open(filepath, FileMode.Create);
 
@@ -55,6 +56,7 @@ public void MockFile_Open_CreatesNewFileFileOnCreateNew()
         {
             string filepath = XFS.Path(@"c:\something\doesnt\exist.txt");
             var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            filesystem.AddDirectory(@"c:\something\doesnt");
 
             var stream = filesystem.File.Open(filepath, FileMode.CreateNew);
 
@@ -153,6 +155,7 @@ public void MockFile_Open_CreatesNewFileOnOpenOrCreate()
         {
             string filepath = XFS.Path(@"c:\something\doesnt\exist.txt");
             var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            filesystem.AddDirectory(@"c:\something\doesnt");
 
             var stream = filesystem.File.Open(filepath, FileMode.OpenOrCreate);
 
@@ -240,5 +243,20 @@ public void MockFile_OpenText_ShouldRetainCreationTime()
             // Assert
             Assert.AreEqual(creationTime, fs.FileInfo.FromFileName(filepath).CreationTime);
         }
+
+        [Test]
+        public void MockFile_Open_ShouldThrowDirectoryNotFoundExceptionIfFileModeCreateAndParentPathDoesNotExist()
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+
+            // Act
+            TestDelegate action = () => fileSystem.File.Open("C:\\Path\\NotFound.ext", FileMode.Create);
+
+            // Assert
+            Assert.IsFalse(fileSystem.Directory.Exists("C:\\path"));
+            var exception = Assert.Throws<DirectoryNotFoundException>(action);
+            Assert.That(exception.Message, Does.StartWith("Could not find a part of the path"));
+        }
     }
 }

TestHelpers.Tests/MockFileTests.cs

@@ -540,6 +540,7 @@ public void MockFile_AppendText_CreatesNewFileForAppendToNonExistingFile()
         {
             string filepath = XFS.Path(@"c:\something\doesnt\exist.txt");
             var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>());
+            filesystem.AddDirectory(@"c:\something\doesnt");
 
             var stream = filesystem.File.AppendText(filepath);
 

TestingHelpers/MockFile.cs

@@ -141,6 +141,9 @@ public override Stream Create(string path)
             }
             mockFileDataAccessor.PathVerifier.IsLegalAbsoluteOrRelative(path, "path");
 
+            if (!mockFileDataAccessor.Directory.Exists(Path.GetDirectoryName(path)))
+                throw new DirectoryNotFoundException($"Could not find a part of the path '{path}'.");
+
             mockFileDataAccessor.AddFile(path, new MockFileData(new byte[0]));
             var stream = OpenWrite(path);
             return stream;