fastapi 0.141.1: UploadFile

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify fastapi.UploadFile in pkg:pypi/fastapi@0.141.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:pypi/fastapi@0.141.1
Demonstrate these symbols/APIs:
  - fastapi.UploadFile

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:ad1eb15b88d2d784e6d6250bb7f1734f76766e606926eced75db3855f02ab3dc","contract":["assert UploadFile initializes with file stream filename size and headers","assert UploadFile async read returns binary payload data from underlying file","assert UploadFile async seek repositions stream and enables partial reads","assert UploadFile async write writes data to file stream and updates contents","assert UploadFile async close closes underlying file stream without errors"],"goal":"verify fastapi.UploadFile in pkg:pypi/fastapi@0.141.1","kind":"HOW","packages":["pkg:pypi/fastapi@0.141.1"],"schemaVersion":1,"symbols":["fastapi.UploadFile"]},"contractCommand":["python","test/contract.py"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"pypi","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"pip","schemaVersion":1},"license":"MIT-0","packages":["pkg:pypi/fastapi@0.141.1"],"schemaVersion":1,"subject":"pkg:pypi/fastapi@0.141.1","symbols":["fastapi.UploadFile"],"verifierAdapter":"python@1"}

[project]
name = "verify-fastapi-uploadfile"
version = "0.1.0"
dependencies = [
    "fastapi==0.141.1",
]

annotated-doc==0.0.5
annotated-types==0.8.0
anyio==4.14.2
fastapi==0.141.1
idna==3.19
pydantic==2.13.4
pydantic-core==2.46.4
starlette==1.6.0
typing-extensions==4.16.0
typing-inspection==0.4.4

{
  "schemaVersion": 1,
  "goal": "verify fastapi.UploadFile in pkg:pypi/fastapi@0.141.1",
  "kind": "HOW",
  "packages": [
    "pkg:pypi/fastapi@0.141.1"
  ],
  "symbols": [
    "fastapi.UploadFile"
  ]
}

import asyncio
import io
from fastapi import UploadFile


def test_upload_file_init():
    payload = b"Hello, FastAPI UploadFile contract test."
    stream = io.BytesIO(payload)
    upload = UploadFile(
        file=stream,
        filename="contract_test.txt",
        size=len(payload),
        headers={"content-type": "text/plain"},
    )
    assert upload.filename == "contract_test.txt"
    assert upload.size == len(payload)
    assert upload.content_type == "text/plain"
    assert upload.headers.get("content-type") == "text/plain"


async def test_upload_file_async_operations():
    payload = b"Hello, FastAPI UploadFile contract test."
    stream = io.BytesIO(payload)
    upload = UploadFile(
        file=stream,
        filename="contract_test.txt",
        size=len(payload),
        headers={"content-type": "text/plain"},
    )

    # assert UploadFile async read returns binary payload data from underlying file
    content = await upload.read()
    assert content == payload

    # assert UploadFile async seek repositions stream and enables partial reads
    await upload.seek(7)
    partial = await upload.read(7)
    assert partial == b"FastAPI"

    # assert UploadFile async write writes data to file stream and updates contents
    await upload.seek(0)
    await upload.write(b"GREETINGS")
    await upload.seek(0)
    read_back = await upload.read(9)
    assert read_back == b"GREETINGS"

    # assert UploadFile async close closes underlying file stream without errors
    await upload.close()


def main():
    test_upload_file_init()
    asyncio.run(test_upload_file_async_operations())
    print("All contract assertions passed.")


if __name__ == "__main__":
    main()