urllib3 2.7.0: response.BaseHTTPResponse

# urllib3 BaseHTTPResponse API

This sample pins `urllib3` 2.7.0 and verifies `urllib3.response.BaseHTTPResponse` interface, attributes, and behavior.

The contract verifies:
- `BaseHTTPResponse` initializes response metadata (status, version, reason, decode_content) and standardizes headers as an `HTTPHeaderDict`.
- `BaseHTTPResponse.chunked` accurately reflects chunked transfer encoding from headers.
- `BaseHTTPResponse.get_redirect_location()` resolves redirect target URLs for HTTP redirect status codes (301, 302, 303, 307, 308) and returns False for non-redirect codes.
- `BaseHTTPResponse` derives from `io.IOBase` and enforces abstract definitions by raising `NotImplementedError` for methods such as `data` and `read()`.
- A concrete subclass implementing `data` enables `json()` to decode and parse structured JSON response payloads.

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 urllib3.response.BaseHTTPResponse in pkg:pypi/urllib3@2.7.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:pypi/urllib3@2.7.0
Demonstrate these symbols/APIs:
  - urllib3.response.BaseHTTPResponse

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:cc6a2725a37a28c4a716a99e8eb5ab253df3b286d47e1ff99045211bb9af232b","contract":["BaseHTTPResponse initializes status, version, version_string, reason, decode_content, and wraps headers in HTTPHeaderDict.","BaseHTTPResponse.chunked is True when Transfer-Encoding header contains chunked and False otherwise.","BaseHTTPResponse.get_redirect_location() returns the Location header on redirect status codes (301, 302, 303, 307, 308) and False on non-redirect codes.","BaseHTTPResponse inherits from io.IOBase and raises NotImplementedError for abstract properties and methods including data and read.","Concrete subclass of BaseHTTPResponse providing data enables json() method to parse and deserialize JSON payloads."],"goal":"verify urllib3.response.BaseHTTPResponse in pkg:pypi/urllib3@2.7.0","kind":"HOW","packages":["pkg:pypi/urllib3@2.7.0"],"schemaVersion":1,"symbols":["urllib3.response.BaseHTTPResponse"]},"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/urllib3@2.7.0"],"schemaVersion":1,"subject":"pkg:pypi/urllib3@2.7.0","symbols":["urllib3.response.BaseHTTPResponse"],"verifierAdapter":"python@1"}

urllib3==2.7.0

{
  "schemaVersion": 1,
  "goal": "verify urllib3.response.BaseHTTPResponse in pkg:pypi/urllib3@2.7.0",
  "kind": "HOW",
  "packages": [
    "pkg:pypi/urllib3@2.7.0"
  ],
  "symbols": [
    "urllib3.response.BaseHTTPResponse"
  ]
}

"""Contract verification test for urllib3.response.BaseHTTPResponse."""

import io
import urllib3.response
from urllib3.response import BaseHTTPResponse
from urllib3._collections import HTTPHeaderDict


def test_base_http_response_initialization() -> None:
    # 1. BaseHTTPResponse initializes status, version, version_string, reason, decode_content, and wraps headers in HTTPHeaderDict
    headers = {"Content-Type": "application/json", "X-Custom": "test-header"}
    resp = BaseHTTPResponse(
        headers=headers,
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=True,
        request_url="https://example.com/test",
    )
    assert resp.status == 200
    assert resp.version == 11
    assert resp.version_string == "HTTP/1.1"
    assert resp.reason == "OK"
    assert resp.decode_content is True
    assert isinstance(resp.headers, HTTPHeaderDict)
    assert resp.headers.get("x-custom") == "test-header"
    assert resp.info() is resp.headers


def test_chunked_detection() -> None:
    # 2. BaseHTTPResponse.chunked is True when Transfer-Encoding header contains chunked and False otherwise
    chunked_resp = BaseHTTPResponse(
        headers={"Transfer-Encoding": "chunked, gzip"},
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=False,
        request_url="https://example.com/stream",
    )
    assert chunked_resp.chunked is True

    unchunked_resp = BaseHTTPResponse(
        headers={"Content-Length": "128"},
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=False,
        request_url="https://example.com/data",
    )
    assert unchunked_resp.chunked is False


def test_redirect_location() -> None:
    # 3. BaseHTTPResponse.get_redirect_location() returns the Location header on redirect status codes (301, 302, 303, 307, 308) and False on non-redirect codes
    redirect_resp = BaseHTTPResponse(
        headers={"Location": "https://example.com/target"},
        status=302,
        version=11,
        version_string="HTTP/1.1",
        reason="Found",
        decode_content=False,
        request_url="https://example.com/source",
    )
    assert redirect_resp.get_redirect_location() == "https://example.com/target"

    redirect_no_loc = BaseHTTPResponse(
        headers={},
        status=301,
        version=11,
        version_string="HTTP/1.1",
        reason="Moved Permanently",
        decode_content=False,
        request_url="https://example.com/source",
    )
    assert redirect_no_loc.get_redirect_location() is None

    non_redirect = BaseHTTPResponse(
        headers={"Location": "https://example.com/target"},
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=False,
        request_url="https://example.com/page",
    )
    assert non_redirect.get_redirect_location() is False


def test_io_base_inheritance_and_abstract_interface() -> None:
    # 4. BaseHTTPResponse inherits from io.IOBase and raises NotImplementedError for abstract properties and methods including data and read
    assert issubclass(BaseHTTPResponse, io.IOBase)
    base_resp = BaseHTTPResponse(
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=False,
        request_url="https://example.com/",
    )
    try:
        _ = base_resp.data
        raise AssertionError("BaseHTTPResponse.data should raise NotImplementedError")
    except NotImplementedError:
        pass

    try:
        base_resp.read()
        raise AssertionError("BaseHTTPResponse.read() should raise NotImplementedError")
    except NotImplementedError:
        pass


def test_concrete_subclass_json_deserialization() -> None:
    # 5. Concrete subclass of BaseHTTPResponse providing data enables json() method to parse and deserialize JSON payloads
    class MockJSONResponse(BaseHTTPResponse):
        def __init__(self, payload: bytes, **kwargs):
            super().__init__(**kwargs)
            self._payload = payload

        @property
        def data(self) -> bytes:
            return self._payload

    json_resp = MockJSONResponse(
        payload=b'{"status": "ok", "items": [1, 2, 3]}',
        headers={"Content-Type": "application/json"},
        status=200,
        version=11,
        version_string="HTTP/1.1",
        reason="OK",
        decode_content=False,
        request_url="https://example.com/api",
    )
    assert json_resp.json() == {"status": "ok", "items": [1, 2, 3]}

    # Also verify urllib3.response.HTTPResponse inherits from BaseHTTPResponse
    assert issubclass(urllib3.response.HTTPResponse, BaseHTTPResponse)


def main() -> None:
    test_base_http_response_initialization()
    test_chunked_detection()
    test_redirect_location()
    test_io_base_inheritance_and_abstract_interface()
    test_concrete_subclass_json_deserialization()
    print("CONTRACT PASS: urllib3.response.BaseHTTPResponse verified offline")


if __name__ == "__main__":
    main()