[Blazor] Fix IBrowserFile Name property to return FileName instead of form field name (#63238)

Author: Copilot

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

@@ -9,7 +9,7 @@ namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping;
 
 internal sealed class BrowserFileFromFormFile(IFormFile formFile) : IBrowserFile
 {
-    public string Name => formFile.Name;
+    public string Name => formFile.FileName;
 
     public DateTimeOffset LastModified => DateTimeOffset.Parse(formFile.Headers.LastModified.ToString(), CultureInfo.InvariantCulture);
 

src/Components/Endpoints/test/Binding/FormDataMapperTests.cs

@@ -2024,7 +2024,7 @@ public void CanDeserialize_ComplexType_CanSerializerBrowserFile()
 
         // Assert
         var browserFile = Assert.IsAssignableFrom<IBrowserFile>(result);
-        Assert.Equal("file", browserFile.Name);
+        Assert.Equal("file.txt", browserFile.Name);
         Assert.Equal(expectedString.Length, browserFile.Size);
         var buffer = new byte[browserFile.Size];
         browserFile.OpenReadStream().Read(buffer);
@@ -2059,18 +2059,18 @@ public void CanDeserialize_ComplexType_CanSerializerIReadOnlyListBrowserFile()
         var browserFiles = Assert.IsAssignableFrom<IReadOnlyList<IBrowserFile>>(result);
         // First file
         var browserFile1 = browserFiles[0];
-        Assert.Equal("file", browserFile1.Name);
+        Assert.Equal("file1.txt", browserFile1.Name);
         Assert.Equal(expectedString1.Length, browserFile1.Size);
         var buffer1 = new byte[browserFile1.Size];
         browserFile1.OpenReadStream().Read(buffer1);
         Assert.Equal(expectedString1, Encoding.UTF8.GetString(buffer1, 0, buffer1.Length));
         // Second files
-        var browserFile2 = browserFiles[0];
-        Assert.Equal("file", browserFile2.Name);
-        Assert.Equal(expectedString1.Length, browserFile2.Size);
+        var browserFile2 = browserFiles[1];
+        Assert.Equal("file2.txt", browserFile2.Name);
+        Assert.Equal(expectedString2.Length, browserFile2.Size);
         var buffer2 = new byte[browserFile2.Size];
-        browserFile1.OpenReadStream().Read(buffer2);
-        Assert.Equal(expectedString1, Encoding.UTF8.GetString(buffer2, 0, buffer2.Length));
+        browserFile2.OpenReadStream().Read(buffer2);
+        Assert.Equal(expectedString2, Encoding.UTF8.GetString(buffer2, 0, buffer2.Length));
     }
 
     [Fact]

src/Components/Endpoints/test/FormMapping/BrowserFileFromFormFileTests.cs

@@ -0,0 +1,105 @@
+// 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.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 BrowserFileFromFormFileTests
+{
+    [Fact]
+    public void Name_ReturnsFormFileFileName_NotFormFileName()
+    {
+        // Arrange
+        const string expectedFileName = "document.pdf";
+        const string formFieldName = "fileInput";
+        
+        var mockFormFile = new Mock<IFormFile>();
+        mockFormFile.Setup(x => x.FileName).Returns(expectedFileName);
+        mockFormFile.Setup(x => x.Name).Returns(formFieldName);
+        
+        var browserFile = new BrowserFileFromFormFile(mockFormFile.Object);
+        
+        // Act
+        var actualName = browserFile.Name;
+        
+        // Assert
+        Assert.Equal(expectedFileName, actualName);
+        Assert.NotEqual(formFieldName, actualName);
+    }
+
+    [Fact]
+    public void TryRead_IBrowserFile_ReturnsCorrectFileName()
+    {
+        // Arrange
+        const string prefixName = "fileInput";
+        const string expectedFileName = "upload.txt";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        
+        var mockFormFile = new Mock<IFormFile>();
+        mockFormFile.Setup(x => x.FileName).Returns(expectedFileName);
+        mockFormFile.Setup(x => x.Name).Returns(prefixName);
+        
+        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(expectedFileName, browserFile.Name);
+    }
+
+    [Fact]
+    public void TryRead_IBrowserFileList_ReturnsCorrectFileNames()
+    {
+        // Arrange
+        const string prefixName = "fileInputs";
+        const string expectedFileName1 = "file1.txt";
+        const string expectedFileName2 = "file2.jpg";
+        var culture = CultureInfo.GetCultureInfo("en-US");
+        
+        var mockFormFile1 = new Mock<IFormFile>();
+        mockFormFile1.Setup(x => x.FileName).Returns(expectedFileName1);
+        mockFormFile1.Setup(x => x.Name).Returns(prefixName);
+        
+        var mockFormFile2 = new Mock<IFormFile>();
+        mockFormFile2.Setup(x => x.FileName).Returns(expectedFileName2);
+        mockFormFile2.Setup(x => x.Name).Returns(prefixName);
+        
+        var formFiles = new List<IFormFile> { mockFormFile1.Object, mockFormFile2.Object };
+        var formFileCollection = new Mock<IFormFileCollection>();
+        formFileCollection.Setup(x => x.GetFiles(prefixName)).Returns(formFiles);
+
+        var buffer = prefixName.ToCharArray().AsMemory();
+        var reader = new FormDataReader(new Dictionary<FormKey, StringValues>(), culture, buffer, formFileCollection.Object);
+        reader.PushPrefix(prefixName);
+
+        var converter = new FileConverter<IReadOnlyList<IBrowserFile>>();
+
+        // Act
+        var result = converter.TryRead(ref reader, typeof(IReadOnlyList<IBrowserFile>), default!, out var browserFiles, out var found);
+
+        // Assert
+        Assert.True(result);
+        Assert.True(found);
+        Assert.NotNull(browserFiles);
+        Assert.Equal(2, browserFiles.Count);
+        Assert.Equal(expectedFileName1, browserFiles[0].Name);
+        Assert.Equal(expectedFileName2, browserFiles[1].Name);
+    }
+}

src/Components/test/E2ETest/ServerRenderingTests/FormHandlingTests/FormWithParentBindingContextTest.cs

@@ -1365,7 +1365,7 @@ public void CanBindToFormWithFiles()
         Assert.Equal($"Profile Picture: {profilePicture.Name}", Browser.Exists(By.Id("profile-picture")).Text);
         Assert.Equal("Documents: 2", Browser.Exists(By.Id("documents")).Text);
         Assert.Equal("Images: 3", Browser.Exists(By.Id("images")).Text);
-        Assert.Equal("Header Photo: Model.HeaderPhoto", Browser.Exists(By.Id("header-photo")).Text);
+        Assert.Equal($"Header Photo: {headerPhoto.Name}", Browser.Exists(By.Id("header-photo")).Text);
         Assert.Equal("Total: 7", Browser.Exists(By.Id("form-collection")).Text);
     }