clawhdf5/crates/clawhdf5-py/tests/conftest.py

"""Shared fixtures for the clawhdf5 Python binding tests."""

import os
import re
import threading
import time
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer

import pytest


@pytest.fixture(scope="session")
def h5py():
    """h5py, or a skip — unless CLAWHDF5_REQUIRE_INTEROP=1, which makes a
    missing h5py a failure (as for the Rust interop suites)."""
    try:
        import h5py as mod
    except ImportError:
        if os.environ.get("CLAWHDF5_REQUIRE_INTEROP") == "1":
            pytest.fail("h5py is required (CLAWHDF5_REQUIRE_INTEROP=1) but not importable")
        pytest.skip("h5py not installed")
    return mod


# ---------------------------------------------------------------------------
# An HTTP server for remote reads
# ---------------------------------------------------------------------------

_RANGE = re.compile(r"^bytes=(\d*)-(\d*)$")


class RangeServer:
    """A static file server on 127.0.0.1, in a thread of this process, that
    answers `Range: bytes=a-b` with 206 and `Content-Range` (the way S3 and
    common web servers do), sends an ETag and honours `If-Match`.

    - `ranges=False`: ignores `Range` and answers 200 with the whole file,
      like a server without range support.
    - `down` (set by `close()`): hang up on every request.
    - `delay`: seconds to wait before answering each request after the
      first `delay_after` ones (a slow network).
    - `log`: every request as `(method, path, range header)`.
    """

    def __init__(self, root, ranges=True):
        self.root = str(root)
        self.ranges = ranges
        self.delay = 0.0
        self.delay_after = 0
        self.down = False
        self.log = []
        self._lock = threading.Lock()
        server = self

        class Handler(BaseHTTPRequestHandler):
            protocol_version = "HTTP/1.1"

            def log_message(self, *args):  # quiet
                pass

            def do_HEAD(self):
                self._serve(body=False)

            def do_GET(self):
                self._serve(body=True)

            def _serve(self, body):
                with server._lock:
                    server.log.append((self.command, self.path, self.headers.get("Range")))
                    n = len(server.log)
                if server.delay and n > server.delay_after:
                    time.sleep(server.delay)
                if server.down:
                    # Hang up without an answer (open keep-alive
                    # connections outlive shutdown(), so close() sets this).
                    self.close_connection = True
                    return
                path = os.path.join(server.root, self.path.lstrip("/").split("?")[0])
                if not os.path.isfile(path):
                    self.send_response(404)
                    self.send_header("Content-Length", "0")
                    self.end_headers()
                    return
                with open(path, "rb") as fh:
                    data = fh.read()
                st = os.stat(path)
                etag = f'"{st.st_mtime_ns:x}-{st.st_size:x}"'
                want = self.headers.get("If-Match")
                if want is not None and want != etag and want != "*":
                    self.send_response(412)
                    self.send_header("Content-Length", "0")
                    self.end_headers()
                    return
                rng = self.headers.get("Range") if server.ranges else None
                m = _RANGE.match(rng.strip()) if rng else None
                if m and (m.group(1) or m.group(2)):
                    size = len(data)
                    if m.group(1):
                        start = int(m.group(1))
                        end = int(m.group(2)) if m.group(2) else size - 1
                    else:
                        start = max(0, size - int(m.group(2)))
                        end = size - 1
                    if start >= size:
                        self.send_response(416)
                        self.send_header("Content-Range", f"bytes */{size}")
                        self.send_header("Content-Length", "0")
                        self.end_headers()
                        return
                    end = min(end, size - 1)
                    part = data[start : end + 1]
                    self.send_response(206)
                    self.send_header("Content-Range", f"bytes {start}-{end}/{size}")
                else:
                    part = data
                    self.send_response(200)
                if server.ranges:
                    self.send_header("Accept-Ranges", "bytes")
                self.send_header("ETag", etag)
                self.send_header("Content-Length", str(len(part)))
                self.send_header("Content-Type", "application/x-hdf5")
                self.end_headers()
                if body:
                    try:
                        self.wfile.write(part)
                    except (BrokenPipeError, ConnectionResetError):
                        pass

        self.httpd = ThreadingHTTPServer(("127.0.0.1", 0), Handler)
        self.httpd.daemon_threads = True
        self.port = self.httpd.server_address[1]
        self.thread = threading.Thread(target=self.httpd.serve_forever, daemon=True)
        self.thread.start()

    def url(self, name):
        return f"http://127.0.0.1:{self.port}/{name}"

    def requests(self):
        with self._lock:
            return len(self.log)

    def close(self):
        self.down = True
        self.httpd.shutdown()
        self.httpd.server_close()


@pytest.fixture
def range_server(tmp_path):
    """A range-capable server over `tmp_path`."""
    server = RangeServer(tmp_path)
    yield server
    server.close()