Fix IBrowserFile LastModified header parsing issue and add tests

Co-authored-by: javiercn <[email protected]>

Author: Copilot

src/Components/Endpoints/src/FormMapping/BrowserFileFromFormFile.cs

@@ -1,17 +1,20 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Globalization;
 using Microsoft.AspNetCore.Components.Forms;
 using Microsoft.AspNetCore.Http;
+using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping;
 
 internal sealed class BrowserFileFromFormFile(IFormFile formFile) : IBrowserFile
 {
     public string Name => formFile.Name;
 
-    public DateTimeOffset LastModified => DateTimeOffset.Parse(formFile.Headers.LastModified.ToString(), CultureInfo.InvariantCulture);
+    public DateTimeOffset LastModified => 
+        HeaderUtilities.TryParseDate(formFile.Headers.LastModified.ToString(), out var lastModified) 
+            ? lastModified 
+            : DateTimeOffset.MinValue;
 
     public long Size => formFile.Length;
 

src/Components/Endpoints/test/FormMapping/Converters/FileConverterTests.cs

@@ -0,0 +1,140 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable enable
+
+using System.Globalization;
+using Microsoft.AspNetCore.Components.Endpoints.FormMapping;
+using Microsoft.AspNetCore.Components.Forms;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+using Moq;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Tests.FormMapping;
+
+public class FileConverterTests
+{
+    [Fact]
+    public void TryRead_IBrowserFile_WithMissingLastModifiedHeader_ReturnsMinValue()
+    {
+        // Arrange
+        const string prefixName = "file";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        
+        var mockFormFile = CreateMockFormFile();
+        var formFileCollection = new Mock<IFormFileCollection>();
+        formFileCollection.Setup(x => x.GetFile(prefixName)).Returns(mockFormFile.Object);
+
+        var buffer = prefixName.ToCharArray().AsMemory();
+        var reader = new FormDataReader(new Dictionary<FormKey, StringValues>(), culture, buffer, formFileCollection.Object);
+        reader.PushPrefix(prefixName);
+
+        var converter = new FileConverter<IBrowserFile>();
+
+        // Act
+        var result = converter.TryRead(ref reader, typeof(IBrowserFile), default!, out var browserFile, out var found);
+
+        // Assert
+        Assert.True(result);
+        Assert.True(found);
+        Assert.NotNull(browserFile);
+        Assert.Equal(DateTimeOffset.MinValue, browserFile.LastModified);
+    }
+
+    [Fact]
+    public void TryRead_IBrowserFile_WithMalformedLastModifiedHeader_ReturnsMinValue()
+    {
+        // Arrange
+        const string prefixName = "file";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        
+        var mockFormFile = CreateMockFormFile(lastModified: "invalid-date");
+        var formFileCollection = new Mock<IFormFileCollection>();
+        formFileCollection.Setup(x => x.GetFile(prefixName)).Returns(mockFormFile.Object);
+
+        var buffer = prefixName.ToCharArray().AsMemory();
+        var reader = new FormDataReader(new Dictionary<FormKey, StringValues>(), culture, buffer, formFileCollection.Object);
+        reader.PushPrefix(prefixName);
+
+        var converter = new FileConverter<IBrowserFile>();
+
+        // Act
+        var result = converter.TryRead(ref reader, typeof(IBrowserFile), default!, out var browserFile, out var found);
+
+        // Assert
+        Assert.True(result);
+        Assert.True(found);
+        Assert.NotNull(browserFile);
+        Assert.Equal(DateTimeOffset.MinValue, browserFile.LastModified);
+    }
+
+    [Fact]
+    public void TryRead_IBrowserFile_WithValidLastModifiedHeader_ReturnsCorrectValue()
+    {
+        // Arrange
+        const string prefixName = "file";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        var expectedDate = new DateTimeOffset(2023, 11, 30, 12, 0, 0, TimeSpan.Zero);
+        
+        var mockFormFile = CreateMockFormFile(lastModified: expectedDate.ToString("r"));
+        var formFileCollection = new Mock<IFormFileCollection>();
+        formFileCollection.Setup(x => x.GetFile(prefixName)).Returns(mockFormFile.Object);
+
+        var buffer = prefixName.ToCharArray().AsMemory();
+        var reader = new FormDataReader(new Dictionary<FormKey, StringValues>(), culture, buffer, formFileCollection.Object);
+        reader.PushPrefix(prefixName);
+
+        var converter = new FileConverter<IBrowserFile>();
+
+        // Act
+        var result = converter.TryRead(ref reader, typeof(IBrowserFile), default!, out var browserFile, out var found);
+
+        // Assert
+        Assert.True(result);
+        Assert.True(found);
+        Assert.NotNull(browserFile);
+        Assert.Equal(expectedDate, browserFile.LastModified);
+    }
+
+    [Fact]
+    public void TryRead_IBrowserFile_WithEmptyLastModifiedHeader_ReturnsMinValue()
+    {
+        // Arrange
+        const string prefixName = "file";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        
+        var mockFormFile = CreateMockFormFile(lastModified: string.Empty);
+        var formFileCollection = new Mock<IFormFileCollection>();
+        formFileCollection.Setup(x => x.GetFile(prefixName)).Returns(mockFormFile.Object);
+
+        var buffer = prefixName.ToCharArray().AsMemory();
+        var reader = new FormDataReader(new Dictionary<FormKey, StringValues>(), culture, buffer, formFileCollection.Object);
+        reader.PushPrefix(prefixName);
+
+        var converter = new FileConverter<IBrowserFile>();
+
+        // Act
+        var result = converter.TryRead(ref reader, typeof(IBrowserFile), default!, out var browserFile, out var found);
+
+        // Assert
+        Assert.True(result);
+        Assert.True(found);
+        Assert.NotNull(browserFile);
+        Assert.Equal(DateTimeOffset.MinValue, browserFile.LastModified);
+    }
+
+    private static Mock<IFormFile> CreateMockFormFile(string? lastModified = null!)
+    {
+        var mockFormFile = new Mock<IFormFile>();
+        var mockHeaders = new Mock<IHeaderDictionary>();
+        
+        mockHeaders.Setup(x => x.LastModified).Returns(new StringValues(lastModified));
+        mockFormFile.Setup(x => x.Headers).Returns(mockHeaders.Object);
+        mockFormFile.Setup(x => x.Name).Returns("testfile.txt");
+        mockFormFile.Setup(x => x.ContentType).Returns("text/plain");
+        mockFormFile.Setup(x => x.Length).Returns(1024);
+        mockFormFile.Setup(x => x.OpenReadStream()).Returns(new MemoryStream());
+
+        return mockFormFile;
+    }
+}