File Upload Testing Checklist

File upload features are deceptively complex. AI-generated upload code frequently lacks file type validation, breaks on large files, and has no progress feedback. This checklist ensures your upload feature handles every scenario users will encounter.

Last updated: 2026-03-14

File Validation

Allowed file types are enforced

Attempt to upload unsupported file types and verify the app rejects them with a clear message about accepted formats.

File size limits are enforced

Upload files exceeding the size limit and verify the app rejects them before uploading rather than failing after.

File names with special characters are handled

Upload files with spaces, unicode characters, and special symbols in their names and verify they are stored correctly.

Empty files are rejected or handled

Upload a zero-byte file and verify the app either rejects it or handles it gracefully without errors.

MIME type validation prevents spoofed extensions

Rename an executable to have an image extension and verify the app validates the actual file content, not just the extension.

Upload Experience

Progress indicator shows during upload

Upload a large file and verify a progress bar or percentage indicator shows the upload status.

Upload can be cancelled mid-progress

Start uploading a large file and cancel it to verify the operation stops cleanly without partial files remaining.

Drag and drop works if supported

Drag files from the desktop onto the upload area and verify they are accepted and processed correctly.

Multiple file upload works if supported

Select multiple files at once and verify they all upload correctly with individual progress and status indicators.

Storage and Retrieval

Uploaded files are accessible after upload

Upload a file and then access it through the app to verify it stored correctly and is retrievable.

File previews or thumbnails generate correctly

Upload images and documents and verify that previews or thumbnails display correctly in the application.

Download of uploaded files works

Download previously uploaded files and verify the content matches the original file without corruption.

File deletion works correctly

Delete an uploaded file and verify it is removed from both the application view and the storage backend.

Error Handling

Network interruption during upload is handled

Disconnect during a file upload and verify the app shows an error message and allows retry.

Storage quota exceeded is handled

If your app has storage limits, exceed them and verify the user sees a clear message about the limit.

Concurrent uploads do not interfere

Upload multiple files simultaneously and verify they do not conflict or overwrite each other.

Server errors during upload show user-friendly messages

Simulate a server error during upload and verify the app displays a helpful message rather than a cryptic error.

Frequently Asked Questions

What file size limit should I set?

Set limits based on your use case and hosting constraints. For profile images, 5MB is generous. For documents, 25MB covers most PDFs. For video, you may need 100MB or more with chunked upload support.

Should I validate files on the client side or server side?

Both. Client-side validation provides fast feedback and prevents unnecessary uploads. Server-side validation is essential for security since client-side checks can be bypassed.

Let human testers run through this checklist for you

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