pillow 12.3.0: PIL.UnidentifiedImageError

# PIL.UnidentifiedImageError in Pillow

This sample pins `pillow` 12.3.0 and verifies `PIL.UnidentifiedImageError` when attempting to open unrecognized, empty, or format-restricted image data.

The contract verifies:
- `PIL.UnidentifiedImageError` is exported by both `PIL` and `PIL.Image` and inherits from `OSError` and `Exception`.
- `Image.open()` raises `UnidentifiedImageError` when given an empty byte stream (`io.BytesIO(b"")`).
- `Image.open()` raises `UnidentifiedImageError` when given arbitrary non-image binary or text data.
- `Image.open()` raises `UnidentifiedImageError` when the image format is not included in the allowed `formats` parameter list.
- `Image.open()` successfully loads valid image streams without raising `UnidentifiedImageError`.

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 PIL.UnidentifiedImageError in pkg:pypi/pillow@12.3.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:pypi/pillow@12.3.0
Demonstrate these symbols/APIs:
  - PIL.UnidentifiedImageError

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:e5fd520d31f724b945820e114a6e87bf563f14ea99052a07e74d47bc014db84f","contract":["PIL.UnidentifiedImageError is exported by both PIL and PIL.Image and inherits from OSError and Exception.","Image.open() raises UnidentifiedImageError when given an empty byte stream (io.BytesIO(b\"\")).","Image.open() raises UnidentifiedImageError when given arbitrary non-image binary or text data.","Image.open() raises UnidentifiedImageError when the image format is not included in the allowed formats parameter list.","Image.open() successfully loads valid image streams without raising UnidentifiedImageError."],"goal":"verify PIL.UnidentifiedImageError in pkg:pypi/pillow@12.3.0","kind":"HOW","packages":["pkg:pypi/pillow@12.3.0"],"schemaVersion":1,"symbols":["PIL.UnidentifiedImageError"]},"contractCommand":["python","test/contract.py"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"pypi","executionContext":"python","language":"python","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"pip","runtime":"python","schemaVersion":1},"license":"MIT-0","packages":["pkg:pypi/pillow@12.3.0"],"schemaVersion":1,"subject":"pkg:pypi/pillow@12.3.0","symbols":["PIL.UnidentifiedImageError"],"verifierAdapter":"python@1"}

pillow==12.3.0

{
  "schemaVersion": 1,
  "goal": "verify PIL.UnidentifiedImageError in pkg:pypi/pillow@12.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:pypi/pillow@12.3.0"
  ],
  "symbols": [
    "PIL.UnidentifiedImageError"
  ]
}

import io
import PIL
from PIL import Image, UnidentifiedImageError

# 1. PIL.UnidentifiedImageError is exported by both PIL and PIL.Image and inherits from OSError and Exception.
assert hasattr(PIL, "UnidentifiedImageError"), "PIL must export UnidentifiedImageError"
assert hasattr(Image, "UnidentifiedImageError"), "PIL.Image must export UnidentifiedImageError"
assert PIL.UnidentifiedImageError is Image.UnidentifiedImageError
assert issubclass(UnidentifiedImageError, OSError), "UnidentifiedImageError must inherit from OSError"
assert issubclass(UnidentifiedImageError, Exception), "UnidentifiedImageError must inherit from Exception"

# 2. Image.open() raises UnidentifiedImageError when given an empty byte stream (io.BytesIO(b"")).
empty_stream = io.BytesIO(b"")
try:
    Image.open(empty_stream)
    raise AssertionError("Image.open() on empty stream did not raise UnidentifiedImageError")
except UnidentifiedImageError as exc:
    assert isinstance(exc, OSError)
    assert len(str(exc)) > 0

# 3. Image.open() raises UnidentifiedImageError when given arbitrary non-image binary or text data.
text_stream = io.BytesIO(b"Plain text payload - not a valid image format.")
try:
    Image.open(text_stream)
    raise AssertionError("Image.open() on text bytes did not raise UnidentifiedImageError")
except UnidentifiedImageError as exc:
    assert isinstance(exc, UnidentifiedImageError)
    assert isinstance(exc, OSError)

random_binary_stream = io.BytesIO(b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f")
try:
    Image.open(random_binary_stream)
    raise AssertionError("Image.open() on random bytes did not raise UnidentifiedImageError")
except UnidentifiedImageError as exc:
    assert isinstance(exc, UnidentifiedImageError)
    assert isinstance(exc, OSError)

# 4. Image.open() raises UnidentifiedImageError when the image format is not included in the allowed formats parameter list.
png_buffer = io.BytesIO()
img_temp = Image.new("RGB", (10, 10), color="blue")
img_temp.save(png_buffer, format="PNG")
img_temp.close()

png_buffer.seek(0)
try:
    # Restrict allowed formats to JPEG only; opening PNG data must raise UnidentifiedImageError
    Image.open(png_buffer, formats=["JPEG"])
    raise AssertionError("Image.open() on PNG with formats=['JPEG'] did not raise UnidentifiedImageError")
except UnidentifiedImageError as exc:
    assert isinstance(exc, UnidentifiedImageError)
    assert isinstance(exc, OSError)

# 5. Image.open() successfully loads valid image streams without raising UnidentifiedImageError.
png_buffer.seek(0)
opened_img = Image.open(png_buffer)
assert opened_img.size == (10, 10)
assert opened_img.format == "PNG"
opened_img.close()

print("CONTRACT PASS: PIL.UnidentifiedImageError verified offline")