feat: Add support for default values on stream creation

src/System.IO.Abstractions.TestingHelpers/IMockFileDataAccessor.cs

@@ -77,6 +77,11 @@ public interface IMockFileDataAccessor : IFileSystem
         /// </summary>
         PathVerifier PathVerifier { get; }
 
+        /// <summary>
+        /// Get if attributes for a file created via stream should be set to default or not
+        /// </summary>
+        bool SetAttributesOnStreamCreation { get; }
+
         /// <summary>
         /// Gets a reference to the underlying file system. 
         /// </summary>

src/System.IO.Abstractions.TestingHelpers/MockFile.cs

@@ -150,7 +150,10 @@ private Stream CreateInternal(string path, FileAccess access, FileOptions option
             mockFileDataAccessor.PathVerifier.IsLegalAbsoluteOrRelative(path, nameof(path));
             VerifyDirectoryExists(path);
 
-            var mockFileData = new MockFileData(new byte[0]);
+            var mockFileData = mockFileDataAccessor.SetAttributesOnStreamCreation
+                ? MockFileData.NewObject
+                : new MockFileData(Array.Empty<byte>());
+
             mockFileDataAccessor.AddFile(path, mockFileData);
             return OpenInternal(path, FileMode.Open, access, options);
         }

src/System.IO.Abstractions.TestingHelpers/MockFileData.cs

@@ -27,6 +27,14 @@ public class MockFileData
             Attributes = (FileAttributes)(-1),
         };
 
+        internal static readonly MockFileData NewObject = new MockFileData(string.Empty)
+        {
+            CreationTime = DateTime.Now,
+            LastWriteTime = DateTime.Now,
+            LastAccessTime = DateTime.Now,
+            Attributes = FileAttributes.Normal,
+        };
+
         /// <summary>
         /// Gets the default date time offset.
         /// E.g. for not existing files.

src/System.IO.Abstractions.TestingHelpers/MockFileStream.cs

@@ -59,7 +59,11 @@ public MockFileStream(
                     throw CommonExceptions.FileNotFound(path);
                 }
 
-                mockFileDataAccessor.AddFile(path, new MockFileData(new byte[] { }));
+                var mfd = mockFileDataAccessor.SetAttributesOnStreamCreation
+                    ? MockFileData.NewObject
+                    : new MockFileData(Array.Empty<byte>());
+
+                mockFileDataAccessor.AddFile(path, mfd);
             }
 
             this.access = access;

src/System.IO.Abstractions.TestingHelpers/MockFileSystem.cs

@@ -87,6 +87,8 @@ public MockFileSystem(IDictionary<string, MockFileData> files, string currentDir
         public IFileSystem FileSystem => this;
         /// <inheritdoc />
         public PathVerifier PathVerifier => pathVerifier;
+        /// <inheritdoc/>
+        public bool SetAttributesOnStreamCreation { get; set; }
 
         private string FixPath(string path, bool checkCaps = false)
         {

tests/System.IO.Abstractions.TestingHelpers.Tests/MockFileInfoTests.cs

@@ -853,6 +853,28 @@ public void MockFileInfo_CreateText_ShouldUpdateCachedDataAndReturnTrueForExists
             Assert.IsTrue(fileInfo.Exists);
         }
 
+        [Test]
+        public void MockFileInfo_Create_ShouldSetProperDefaultAttributes()
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+            fileSystem.SetAttributesOnStreamCreation = true;
+            var file = XFS.Path(@"C:\test\test.txt");
+            var fi = fileSystem.FileInfo.FromFileName(file);
+            if (!fi.Directory.Exists)
+            {
+                fi.Directory.Create();
+            }
+
+            // Act
+            using (var stream = fi.Create())
+            {
+                // Assert
+                Assert.AreEqual(FileAttributes.Normal, fi.Attributes);
+                Assert.LessOrEqual(DateTime.Now - fi.CreationTime, TimeSpan.FromSeconds(1));
+            }
+        }
+
         [Test]
         public void MockFileInfo_Delete_ShouldUpdateCachedDataAndReturnFalseForExists()
         {

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

@@ -184,5 +184,25 @@ public void MockFileStream_Flush_ShouldNotChangePosition()
                 Assert.AreEqual(200, stream.Position);
             }
         }
+
+        [Test]
+        public void MockFileStream_Create_ShouldSetProperDefaultAttributes()
+        {
+            // Arrange
+            var fileSystem = new MockFileSystem();
+            fileSystem.SetAttributesOnStreamCreation = true;
+            var dir = XFS.Path(@"C:\test\");
+            var file = XFS.Path(@"C:\test\test.txt");
+            fileSystem.Directory.CreateDirectory(dir);
+
+            // Act
+            using (var stream = fileSystem.FileStream.Create(file, FileMode.Create))
+            {
+                var fi = fileSystem.FileInfo.FromFileName(file);
+                // Assert
+                Assert.AreEqual(FileAttributes.Normal, fi.Attributes);
+                Assert.LessOrEqual(DateTime.Now - fi.CreationTime, TimeSpan.FromSeconds(1));
+            }
+        }
     }
 }