feat(client): add durable HTTP task state

client/tests/remote/test_http_transport.py

@@ -0,0 +1,184 @@
+from __future__ import annotations
+
+import os
+import http.client
+import unittest
+from unittest import mock
+
+from cmbuyer_client.core.errors import AmbiguousRemoteError, ProtocolRemoteError
+from cmbuyer_client.remote.http_transport import HttpTransport
+
+
+class FakeResponse:
+    status = 200
+
+    def __init__(self, body: bytes = b"{}", headers: list[tuple[str, str]] | None = None) -> None:
+        self.body = body
+        self.headers = headers or [("Content-Type", "application/json")]
+
+    def getheader(self, name: str) -> str | None:
+        return str(len(self.body)) if name == "Content-Length" else None
+
+    def getheaders(self) -> list[tuple[str, str]]:
+        return self.headers
+
+    def read(self, maximum: int) -> bytes:
+        return self.body[:maximum]
+
+
+class FakeConnection:
+    def __init__(self, host: str, port: int, timeout: int) -> None:
+        self.created = (host, port, timeout)
+        self.calls = 0
+        self.closed = False
+        self.sent_headers: dict[str, str] = {}
+        self.response = FakeResponse()
+
+    def request(self, method: str, path: str, body: bytes, headers: dict[str, str]) -> None:
+        self.calls += 1
+        self.sent_headers = headers
+
+    def getresponse(self) -> FakeResponse:
+        return self.response
+
+    def close(self) -> None:
+        self.closed = True
+
+
+class HttpTransportTests(unittest.TestCase):
+    def test_exact_loopback_and_proxy_environment_is_irrelevant(self) -> None:
+        made: list[FakeConnection] = []
+
+        def factory(*args: object, **kwargs: object) -> FakeConnection:
+            connection = FakeConnection(*args, **kwargs)
+            made.append(connection)
+            return connection
+
+        with mock.patch.dict(os.environ, {"HTTP_PROXY": "http://example.invalid:9999"}):
+            result = HttpTransport(connection_factory=factory).request(
+                "POST", "/api/v1/tasks/claim-next", (("Content-Type", "application/json"),), b"{}", response_limit=10
+            )
+        self.assertEqual(result.status, 200)
+        self.assertEqual(made[0].created, ("127.0.0.1", 8080, 10))
+        self.assertEqual(made[0].calls, 1)
+        self.assertTrue(made[0].closed)
+
+        for url in ("http://localhost:8080", "http://127.0.0.1:8081", "http://127.0.0.1:8080/", "https://127.0.0.1:8080"):
+            with self.subTest(url=url), self.assertRaises(ProtocolRemoteError):
+                HttpTransport(url)
+
+    def test_network_failure_is_ambiguous_without_retry(self) -> None:
+        class Broken(FakeConnection):
+            def getresponse(self) -> FakeResponse:
+                raise OSError("offline")
+
+        made: list[Broken] = []
+
+        def factory(*args: object, **kwargs: object) -> Broken:
+            connection = Broken(*args, **kwargs)
+            made.append(connection)
+            return connection
+
+        with self.assertRaises(AmbiguousRemoteError):
+            HttpTransport(connection_factory=factory).request(
+                "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=10
+            )
+        self.assertEqual(made[0].calls, 1)
+
+    def test_generator_headers_and_content_length_framing(self) -> None:
+        made: list[FakeConnection] = []
+
+        def factory(*args: object, **kwargs: object) -> FakeConnection:
+            connection = FakeConnection(*args, **kwargs)
+            made.append(connection)
+            return connection
+
+        headers = ((name, value) for name, value in (("Content-Type", "application/json"), ("Accept", "application/json")))
+        HttpTransport(connection_factory=factory).request(
+            "POST", "/api/v1/tasks/claim-next", headers, b"{}", response_limit=8
+        )
+        self.assertEqual(made[0].sent_headers["Content-Type"], "application/json")
+        self.assertEqual(made[0].sent_headers["Accept"], "application/json")
+
+        legal = FakeConnection("127.0.0.1", 8080, 10)
+        legal.response = FakeResponse(b"{}", [("Content-Length", "2")])
+        accepted = HttpTransport(connection_factory=lambda *args, **kwargs: legal).request(
+            "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=8
+        )
+        self.assertEqual(accepted.body, b"{}")
+        chunked = FakeConnection("127.0.0.1", 8080, 10)
+        chunked.response = FakeResponse(b"{}", [("Transfer-Encoding", "Chunked")])
+        accepted_chunked = HttpTransport(connection_factory=lambda *args, **kwargs: chunked).request(
+            "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=8
+        )
+        self.assertEqual(accepted_chunked.body, b"{}")
+
+        cases = (
+            ([('Transfer-Encoding', 'chunked'), ('Content-Length', '2')], b'{}'),
+            ([('Transfer-Encoding', 'gzip')], b'{}'),
+            ([('Transfer-Encoding', ' chunked ')], b'{}'),
+            ([('Transfer-Encoding', 'chunked,gzip')], b'{}'),
+            ([('Transfer-Encoding', 'chunked'), ('Transfer-Encoding', 'chunked')], b'{}'),
+            ([("Content-Length", "2"), ("Content-Length", "2")], b"{}"),
+            ([("Content-Length", "+2")], b"{}"),
+            ([("Content-Length", "-0")], b""),
+            ([("Content-Length", "2x")], b"{}"),
+            ([("Content-Length", "3")], b"{}"),
+            ([("Content-Length", "1")], b"{}"),
+            ([("Content-Length", "999")], b"{}"),
+            ([], b"0123456789"),
+        )
+        for response_headers, body in cases:
+            with self.subTest(headers=response_headers, body=body):
+                connection = FakeConnection("127.0.0.1", 8080, 10)
+                connection.response = FakeResponse(body, response_headers)
+                with self.assertRaises(AmbiguousRemoteError):
+                    HttpTransport(connection_factory=lambda *args, value=connection, **kwargs: value).request(
+                        "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=8
+                    )
+
+    def test_timeout_incomplete_read_and_close_do_not_expose_partial_body(self) -> None:
+        token = ("a" * 64).encode()
+
+        class Incomplete(FakeResponse):
+            def read(self, maximum: int) -> bytes:
+                raise http.client.IncompleteRead(token, 1)
+
+        class Connection(FakeConnection):
+            def getresponse(self) -> FakeResponse:
+                return Incomplete()
+
+            def close(self) -> None:
+                self.closed = True
+                raise OSError("close failed")
+
+        with self.assertRaises(AmbiguousRemoteError) as captured:
+            HttpTransport(connection_factory=Connection).request(
+                "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=128
+            )
+        self.assertNotIn(token.decode(), _exception_graph(captured.exception))
+
+        class Timeout(FakeConnection):
+            def getresponse(self) -> FakeResponse:
+                raise TimeoutError("timed out")
+
+        with self.assertRaises(AmbiguousRemoteError):
+            HttpTransport(connection_factory=Timeout).request(
+                "POST", "/api/v1/tasks/claim-next", (), b"{}", response_limit=8
+            )
+
+
+def _exception_graph(error: BaseException) -> str:
+    seen: set[int] = set()
+    values: list[str] = []
+    pending: list[object] = [error]
+    while pending:
+        value = pending.pop()
+        if id(value) in seen:
+            continue
+        seen.add(id(value))
+        values.append(repr(value))
+        if isinstance(value, BaseException):
+            pending.extend(item for item in (value.__cause__, value.__context__) if item is not None)
+            pending.extend(value.__dict__.values())
+    return "\n".join(values)