Back to API Practice

Interactive API trainer

File Upload API Testing Practice

Send fake upload metadata, inspect validation and storage responses, then write what you would test for file safety, permissions, scanning, and reliability.

Start writing test ideasTry API sandbox

How to use this trainer

Choose, send, inspect, write, improve

Safe client-side simulator. No real backend is called and no real data is sent.

  1. 1Choose a preset case
  2. 2Send a simulated request
  3. 3Read the response and QA note
  4. 4Write what you would test
  5. 5Check your coverage

Interactive sandbox

Try the API request

Edit fake file metadata, send a simulated POST /api/files/upload request, and inspect validation, scanning, storage, and auth behavior. No file is uploaded.

Request

Build the upload request

POST/api/files/upload

Test case presets

Choose a case, inspect the fake response, then write what you would test.

Happy path

Validation

Security / reliability

Response

Fake API result

Send a simulated request to see status, response JSON, QA note, and upload risks. No file content is sent.

List valid upload, missing file, unsupported type, too large file, empty file, duplicate file, malware scan failure, auth, permissions, storage outage, interrupted upload, logs, metrics, and progress states.

Tip: a stronger answer usually mixes happy path, negative cases, state changes, data, backend, UX, accessibility, and risk.

How to structure your answer

Happy pathNegative casesData rulesSecurity/API risksUX/performance
API ReferenceEndpoint, request fields, responses, and business rulesExpand

API reference

File Upload endpoint

Use this reference while testing validation, malware scanning, storage consistency, permissions, and upload failure recovery.

Endpoint

POST/api/files/upload

Authentication

Bearer token required before file processing.

Success response

201 Created

Success response body

{
  "fileId": "file_123",
  "fileName": "report.pdf",
  "sizeBytes": 240000,
  "contentType": "application/pdf",
  "scanStatus": "clean",
  "url": "/api/files/file_123"
}

Business rules

  • multipart/form-data request must include exactly one file field
  • allowed content types are enforced server-side
  • maximum file size is 10 MB
  • empty files are rejected unless product says otherwise
  • malware scan result controls whether file is usable
  • storage and metadata persistence must stay consistent
  • tenant and folder permissions apply before file processing
  • file content must never be sent to analytics or logs

API interview guide

What this File Upload API practice covers

This scenario trains upload API testing where file validation, metadata, malware scanning, storage side effects, permissions, and failure recovery are all high risk.

Key risks covered

  • - Valid upload returns file id, metadata, scan status, and safe access URL behavior.
  • - Missing file, empty file, too-large file, unsupported type, MIME mismatch, and duplicate file.
  • - Malware scan clean, infected, pending, failed, and scanner unavailable states.
  • - Tenant permissions, signed URL safety, path traversal, stored XSS, and no file-content logging.
  • - Storage outage, partial rollback, interrupted upload, retry behavior, quotas, and audit logs.

Example interview prompt

How would you test a File Upload API that accepts multipart files, validates metadata, scans content, and stores results?

Common mistakes

  • - Only testing one valid file and one large file.
  • - Missing MIME mismatch, malware states, duplicate behavior, and storage rollback.
  • - Not checking tenant access, signed URLs, path traversal, or file data in logs.
Related practice:Create User APISearch APIPagination API