tests/test_derivepassphrase_ssh_agent/test_000_basic.py (b21188f) - derivepassphrase.git

test_000_basic.py

# SPDX-FileCopyrightText: 2026 Marco Ricci <software@the13thletter.info>
#
# SPDX-License-Identifier: Zlib

"""Tests for `derivepassphrase.ssh_agent`: basic tests."""

from __future__ import annotations

import base64
import contextlib
import importlib.metadata
import re
import sys
from typing import TYPE_CHECKING, Final, cast

import click
import hypothesis
import pytest
from hypothesis import strategies
from typing_extensions import TypeAlias

from derivepassphrase import _types, ssh_agent, vault
from derivepassphrase._internals import cli_helpers
from derivepassphrase.ssh_agent import socketprovider
from tests import data, machinery
from tests.data import callables
from tests.machinery import hypothesis as hypothesis_machinery
from tests.machinery import pytest as pytest_machinery

if TYPE_CHECKING:
    from collections.abc import (
        Callable,
        Generator,
        Mapping,
        Sequence,
    )

from typing_extensions import Any, Literal

if sys.version_info < (3, 11):
    from exceptiongroup import ExceptionGroup

class Parametrize(pytest_machinery.Parametrize):
    BAD_ENTRY_POINTS = pytest.mark.parametrize(
        "additional_entry_points",
        [
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_callable.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_callable",
                    ),
                ],
                id="not-callable",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_name_exists.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_name_exists",
                    ),
                ],
                id="name-already-exists",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.faulty_entry_alias_exists.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: faulty_entry_alias_exists",
                    ),
                ],
                id="alias-already-exists",
            ),
        ],
    )
    GOOD_ENTRY_POINTS = pytest.mark.parametrize(
        "additional_entry_points",
        [
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=data.ssh_auth_sock_on_posix_entry.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: ssh_auth_sock_on_posix_entry",
                    ),
                    importlib.metadata.EntryPoint(
                        name=data.ssh_auth_sock_on_windows_entry.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data: ssh_auth_sock_on_windows_entry",
                    ),
                ],
                id="existing-entries",
            ),
            pytest.param(
                [
                    importlib.metadata.EntryPoint(
                        name=callables.provider_entry1.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data.callables: provider_entry1",
                    ),
                    importlib.metadata.EntryPoint(
                        name=callables.provider_entry2.key,
                        group=socketprovider.SocketProvider.ENTRY_POINT_GROUP_NAME,
                        value="tests.data.callables: provider_entry2",
                    ),
                ],
                id="new-entries",
            ),
        ],
    )
    EXISTING_REGISTRY_ENTRIES = pytest.mark.parametrize(
        "existing",
        [
            _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_POSIX,
            _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_WINDOWS,
        ],
        ids=str,
    )
    SSH_STRING_EXCEPTIONS = hypothesis_machinery.explicit_examples(
        ["input", "exc_type", "exc_pattern"],
        [
            pytest.param(
                "some string", TypeError, "invalid payload type", id="str"
            ),
        ],
    )
    UINT32_EXCEPTIONS = hypothesis_machinery.explicit_examples(
        ["input", "exc_type", "exc_pattern"],
        [
            pytest.param(
                10000000000000000,
                OverflowError,
                "int too big to convert",
                id="10000000000000000",
            ),
            pytest.param(
                -1,
                OverflowError,
                "can't convert negative int to unsigned",
                id="-1",
            ),
        ],
    )
    SSH_UNSTRING_EXCEPTIONS = hypothesis_machinery.explicit_examples(
        ["input", "exc_type", "exc_pattern", "parts"],
        [
            pytest.param(
                b"ssh",
                ValueError,
                "malformed SSH byte string",
                None,
                id="unencoded",
            ),
            pytest.param(
                b"\x00\x00\x00\x08ssh-rsa",
                ValueError,
                "malformed SSH byte string",
                None,
                id="truncated",
            ),
            pytest.param(
                b"\x00\x00\x00\x04XXX trailing text",
                ValueError,
                "malformed SSH byte string",
                (b"XXX ", b"trailing text"),
                id="trailing-data",
            ),
        ],
    )
    SSH_STRING_INPUT = hypothesis_machinery.explicit_examples(
        ["input", "expected"],
        [
            pytest.param(
                b"ssh-rsa",
                b"\x00\x00\x00\x07ssh-rsa",
                id="ssh-rsa",
            ),
            pytest.param(
                b"ssh-ed25519",
                b"\x00\x00\x00\x0bssh-ed25519",
                id="ssh-ed25519",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(b"ssh-ed25519"),
                b"\x00\x00\x00\x0f\x00\x00\x00\x0bssh-ed25519",
                id="string(ssh-ed25519)",
            ),
        ],
    )
    SSH_UNSTRING_INPUT = hypothesis_machinery.explicit_examples(
        ["input", "expected"],
        [
            pytest.param(
                b"\x00\x00\x00\x07ssh-rsa",
                b"ssh-rsa",
                id="ssh-rsa",
            ),
            pytest.param(
                ssh_agent.SSHAgentClient.string(b"ssh-ed25519"),
                b"ssh-ed25519",
                id="ssh-ed25519",
            ),
        ],
    )
    UINT32_INPUT = hypothesis_machinery.explicit_examples(
        ["input", "expected"],
        [
            pytest.param(16777216, b"\x01\x00\x00\x00", id="16777216"),
        ],
    )
    SIGN_ERROR_RESPONSES = hypothesis_machinery.explicit_examples(
        [
            "key",
            "check",
            "response_code",
            "response",
            "exc_type",
            "exc_pattern",
        ],
        [
            pytest.param(
                b"invalid-key",
                True,
                _types.SSH_AGENT.FAILURE,
                b"",
                KeyError,
                "target SSH key not loaded into agent",
                id="key-not-loaded",
            ),
            pytest.param(
                data.SUPPORTED_KEYS["ed25519"].public_key_data,
                True,
                _types.SSH_AGENT.FAILURE,
                b"",
                ssh_agent.SSHAgentFailedError,
                "failed to complete the request",
                id="failed-to-complete",
            ),
        ],
    )
    SSH_KEY_SELECTION = pytest.mark.parametrize(
        ["key", "single"],
        [
            (value.public_key_data, False)
            for value in data.SUPPORTED_KEYS.values()
        ]
        + [(callables.list_keys_singleton()[0].key, True)],
        ids=[*data.SUPPORTED_KEYS.keys(), "singleton"],
    )
    SH_EXPORT_LINES = hypothesis_machinery.explicit_examples(
        ["line", "env_name", "value"],
        [
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170; export SSH_AUTH_SOCK;",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="value-export-semicolon-pageant",
            ),
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/ssh-3CSTC1W5M22A/agent.27270; export SSH_AUTH_SOCK;",
                "SSH_AUTH_SOCK",
                "/tmp/ssh-3CSTC1W5M22A/agent.27270",
                id="value-export-semicolon-openssh",
            ),
            pytest.param(
                "SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170; export SSH_AUTH_SOCK",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="value-export-pageant",
            ),
            pytest.param(
                "export SSH_AUTH_SOCK=/tmp/ssh-3CSTC1W5M22A/agent.27270;",
                "SSH_AUTH_SOCK",
                "/tmp/ssh-3CSTC1W5M22A/agent.27270",
                id="export-value-semicolon-openssh",
            ),
            pytest.param(
                "export SSH_AUTH_SOCK=/tmp/pageant.user/pageant.27170",
                "SSH_AUTH_SOCK",
                "/tmp/pageant.user/pageant.27170",
                id="export-value-pageant",
            ),
            pytest.param(
                "SSH_AGENT_PID=27170; export SSH_AGENT_PID;",
                "SSH_AGENT_PID",
                "27170",
                id="pid-export-semicolon",
            ),
            pytest.param(
                "SSH_AGENT_PID=27170; export SSH_AGENT_PID",
                "SSH_AGENT_PID",
                "27170",
                id="pid-export",
            ),
            pytest.param(
                "export SSH_AGENT_PID=27170;",
                "SSH_AGENT_PID",
                "27170",
                id="export-pid-semicolon",
            ),
            pytest.param(
                "export SSH_AGENT_PID=27170",
                "SSH_AGENT_PID",
                "27170",
                id="export-pid",
            ),
            pytest.param(
                "export VARIABLE=value; export OTHER_VARIABLE=other_value;",
                "VARIABLE",
                None,
                id="export-too-much",
            ),
            pytest.param(
                "VARIABLE=value",
                "VARIABLE",
                None,
                id="no-export",
            ),
        ],
    )
    PUBLIC_KEY_DATA = pytest.mark.parametrize(
        "public_key_struct",
        list(data.SUPPORTED_KEYS.values()),
        ids=list(data.SUPPORTED_KEYS.keys()),
    )
    REQUEST_ERROR_RESPONSES = hypothesis_machinery.explicit_examples(
        ["request_code", "response_code", "exc_type", "exc_pattern"],
        [
            pytest.param(
                _types.SSH_AGENTC.REQUEST_IDENTITIES,
                _types.SSH_AGENT.SUCCESS,
                ssh_agent.SSHAgentFailedError,
                re.escape(
                    "[Code {:d}]".format(  # noqa: UP032
                        int(_types.SSH_AGENT.IDENTITIES_ANSWER)
                    )
                ),
                id="REQUEST_IDENTITIES-expect-SUCCESS",
            ),
        ],
    )
    TRUNCATED_AGENT_RESPONSES = hypothesis_machinery.explicit_examples(
        "response",
        [
            b"\x00\x00",
            b"\x00\x00\x00\x1f some bytes missing",
        ],
        ids=["in-header", "in-body"],
    )
    LIST_KEYS_ERROR_RESPONSES = hypothesis_machinery.explicit_examples(
        ["response_code", "response", "exc_type", "exc_pattern"],
        [
            pytest.param(
                _types.SSH_AGENT.FAILURE,
                b"",
                ssh_agent.SSHAgentFailedError,
                "failed to complete the request",
                id="failed-to-complete",
            ),
            pytest.param(
                _types.SSH_AGENT.IDENTITIES_ANSWER,
                b"\x00\x00\x00\x01",
                EOFError,
                "truncated response",
                id="truncated-response",
            ),
            pytest.param(
                _types.SSH_AGENT.IDENTITIES_ANSWER,
                b"\x00\x00\x00\x00abc",
                ssh_agent.TrailingDataError,
                "Overlong response",
                id="overlong-response",
            ),
        ],
    )
    QUERY_EXTENSIONS_MALFORMED_RESPONSES = (
        hypothesis_machinery.explicit_examples(
            "response_data",
            [
                pytest.param(b"\xde\xad\xbe\xef", id="truncated"),
                pytest.param(
                    b"\x00\x00\x00\x0fwrong extension", id="wrong-extension"
                ),
                pytest.param(
                    b"\x00\x00\x00\x05query\xde\xad\xbe\xef", id="with-trailer"
                ),
                pytest.param(
                    b"\x00\x00\x00\x05query\x00\x00\x00\x04ext1\x00\x00",
                    id="with-extra-fields",
                ),
            ],
        )
    )
    ALL_SSH_TEST_KEYS = pytest.mark.parametrize(
        ["ssh_test_key_type", "ssh_test_key"],
        list(data.ALL_KEYS.items()),
        ids=data.ALL_KEYS.keys(),
    )
    RESOLVE_CHAINS = hypothesis_machinery.explicit_examples(
        ["terminal", "chain"],
        [
            pytest.param("callable", ["a"], id="callable-1"),
            pytest.param("callable", ["a", "b", "c", "d"], id="callable-4"),
            pytest.param("alias", ["e"], id="alias-1"),
            pytest.param("alias", ["e", "f", "g", "h", "i"], id="alias-5"),
            pytest.param("unimplemented", ["j"], id="unimplemented-1"),
            pytest.param("unimplemented", ["j", "k"], id="unimplemented-2"),
        ],
    )

class Strategies:
    """Common hypothesis data generation strategies."""

@staticmethod
    def select_invalid_pipe_names(candidate: str) -> bool:
        """Select candidate strings that are invalid named pipe names."""
        candidate = candidate.lower().replace("/", "\\")
        return not candidate.startswith(socketprovider.PIPE_PREFIX)

@classmethod
    def bad_named_pipe_names(cls) -> strategies.SearchStrategy[str]:
        r"""Generate invalid names for Windows named pipes.

Invalid named pipe names do not lie below the `\\.\pipe\` path.
        They also may or may not contain characters that are invalid
        in paths on The Annoying OS.

"""
        # This is an environment string on The Annoying OS, so it must
        # at least be a non-empty C string, i.e., without embedded NULs.
        return strategies.text(
            alphabet=strategies.characters(min_codepoint=1), min_size=1
        ).filter(cls.select_invalid_pipe_names)

@staticmethod
    def io_operations_on_handles() -> strategies.SearchStrategy[
        Callable[[_types.SSHAgentSocket], Any]
    ]:
        """Return an I/O operation on an SSH agent socket."""
        return strategies.one_of(
            strategies.integers(min_value=0).map(
                lambda i: lambda handle: handle.recv(i)
            ),
            strategies.binary().map(
                lambda bs: lambda handle: handle.sendall(bs)
            ),
        )

class TestStaticFunctionality:
    """Test the static functionality of the `ssh_agent` module."""

# TODO(the-13th-letter): Put this functionality into the
    # tests.data.callables module. It is nice to have for other tests as
    # well: `vault` tests, stubbed SSH agent tests, agent protocol
    # response queue tests, etc. Also add an unstring and a u32
    # function.
    @staticmethod
    def as_ssh_string(bytestring: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis data generation.

"""
        return int.to_bytes(len(bytestring), 4, "big") + bytestring

@staticmethod
    def canonicalize1(data: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis testing.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        return ssh_agent.SSHAgentClient.string(
            ssh_agent.SSHAgentClient.unstring(data)
        )

@staticmethod
    def canonicalize2(data: bytes) -> bytes:
        """Return an encoded SSH string from a bytestring.

This is a helper function for hypothesis testing.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        unstringed, trailer = ssh_agent.SSHAgentClient.unstring_prefix(data)
        assert not trailer
        return ssh_agent.SSHAgentClient.string(unstringed)

class TestShellExportScriptParsing:
    """Test the shell export script parsing utility function."""

@Parametrize.SH_EXPORT_LINES
    def test_sh_export_line_parsing(
        self, line: str, env_name: str, value: str | None
    ) -> None:
        """[`tests.data.callables.parse_sh_export_line`][] works."""
        if value is not None:
            assert (
                callables.parse_sh_export_line(line, env_name=env_name)
                == value
            )
        else:
            with pytest.raises(ValueError, match="Cannot parse sh line:"):
                callables.parse_sh_export_line(line, env_name=env_name)

class TestSSHProtocolDatatypes(TestStaticFunctionality):
    """Tests for the utility functions for the SSH protocol datatypes."""

@Parametrize.UINT32_INPUT
    def test_uint32(self, input: int, expected: bytes | bytearray) -> None:
        """`uint32` encoding works."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert uint32(input) == expected

@hypothesis.given(
        num=strategies.integers(min_value=0, max_value=0xFFFFFFFF)
    )
    @hypothesis.example(num=0xDEADBEEF)
    def test_uint32_from_number(self, num: int) -> None:
        """`uint32` encoding works, starting from numbers."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert int.from_bytes(uint32(num), "big", signed=False) == num

@hypothesis.given(bytestring=strategies.binary(min_size=4, max_size=4))
    @hypothesis.example(bytestring=b"\xde\xad\xbe\xef")
    def test_uint32_from_bytestring(self, bytestring: bytes) -> None:
        """`uint32` encoding works, starting from length four byte strings."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        assert (
            uint32(int.from_bytes(bytestring, "big", signed=False))
            == bytestring
        )

@Parametrize.SSH_STRING_INPUT
    def test_string(
        self, input: bytes | bytearray, expected: bytes | bytearray
    ) -> None:
        """SSH string encoding works."""
        string = ssh_agent.SSHAgentClient.string
        assert bytes(string(input)) == expected

@hypothesis.given(bytestring=strategies.binary(max_size=0x0001FFFF))
    # example with highest order bit set
    @hypothesis.example(bytestring=b"DEADBEEF" * 10000)
    def test_string_from_bytestring(self, bytestring: bytes) -> None:
        """SSH string encoding works, starting from a byte string."""
        res = ssh_agent.SSHAgentClient.string(bytestring)
        assert res.startswith((b"\x00\x00", b"\x00\x01"))
        assert int.from_bytes(res[:4], "big", signed=False) == len(bytestring)
        assert res[4:] == bytestring

@Parametrize.SSH_UNSTRING_INPUT
    def test_unstring(
        self, input: bytes | bytearray, expected: bytes | bytearray
    ) -> None:
        """SSH string decoding works."""
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        assert bytes(unstring(input)) == expected
        assert tuple(bytes(x) for x in unstring_prefix(input)) == (
            expected,
            b"",
        )

@hypothesis.given(bytestring=strategies.binary(max_size=0x00FFFFFF))
    # should not double-decode
    @hypothesis.example(bytestring=b"\x00\x00\x00\x07ssh-rsa")
    # should not choke on ill-formed SSH string payloads
    @hypothesis.example(bytestring=b"\x00\x00\x00\x01")
    def test_unstring_of_string_of_data(self, bytestring: bytes) -> None:
        """SSH string decoding of encoded SSH strings works.

References:

* [David R. MacIver: The Encode/Decode invariant][ENCODE_DECODE]

[ENCODE_DECODE]: https://hypothesis.works/articles/encode-decode-invariant/

"""
        string = ssh_agent.SSHAgentClient.string
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        encoded = string(bytestring)
        assert unstring(encoded) == bytestring
        assert unstring_prefix(encoded) == (bytestring, b"")
        trailing_data = b"  trailing data"
        encoded2 = string(bytestring) + trailing_data
        assert unstring_prefix(encoded2) == (bytestring, trailing_data)

@hypothesis.given(
        encoded=strategies.binary(max_size=0x00FFFFFF).map(
            # Scoping issues, and the fact that staticmethod objects
            # (before class finalization) are not callable, necessitate
            # wrapping this staticmethod call in a lambda.
            lambda x: TestStaticFunctionality.as_ssh_string(x)  # noqa: PLW0108
        ),
    )
    def test_string_of_unstring_of_data(self, encoded: bytes) -> None:
        """SSH string decoding of encoded SSH strings works.

References:

* [David R. MacIver: Another invariant to test for
            encoders][DECODE_ENCODE]

[DECODE_ENCODE]: https://hypothesis.works/articles/canonical-serialization/

"""
        # Both canonicalization functions are built with slightly
        # different primitives.  However, because SSH string encoding is
        # a bijective encoding, their result should be the same.
        canonical_functions = [self.canonicalize1, self.canonicalize2]
        # Test encoding equivalence.
        for canon1 in canonical_functions:
            for canon2 in canonical_functions:
                assert canon1(encoded) == canon2(encoded)
        # Test idempotence.
        for canon1 in canonical_functions:
            for canon2 in canonical_functions:
                assert canon1(canon2(encoded)) == canon1(encoded)

# TODO(the-13th-letter): Write a hypothesis strategy.
    @Parametrize.UINT32_EXCEPTIONS
    def test_uint32_exceptions(
        self, input: int, exc_type: type[Exception], exc_pattern: str
    ) -> None:
        """`uint32` encoding fails for out-of-bound values."""
        uint32 = ssh_agent.SSHAgentClient.uint32
        with pytest.raises(exc_type, match=exc_pattern):
            uint32(input)

# TODO(the-13th-letter): Write a hypothesis strategy.
    @Parametrize.SSH_STRING_EXCEPTIONS
    def test_string_exceptions(
        self, input: Any, exc_type: type[Exception], exc_pattern: str
    ) -> None:
        """SSH string encoding fails for non-strings."""
        string = ssh_agent.SSHAgentClient.string
        with pytest.raises(exc_type, match=exc_pattern):
            string(input)

# TODO(the-13th-letter): Write a hypothesis strategy.
    @Parametrize.SSH_UNSTRING_EXCEPTIONS
    def test_unstring_exceptions(
        self,
        input: bytes,
        exc_type: type[Exception],
        exc_pattern: str,
        parts: tuple[bytes, bytes] | None,
    ) -> None:
        """SSH string decoding fails for invalid values."""
        unstring = ssh_agent.SSHAgentClient.unstring
        unstring_prefix = ssh_agent.SSHAgentClient.unstring_prefix
        with pytest.raises(exc_type, match=exc_pattern):
            unstring(input)
        if parts is not None:
            assert unstring_prefix(input) == parts
        else:
            with pytest.raises(exc_type, match=exc_pattern):
                unstring_prefix(input)

# TODO(the-13th-letter): Introduce a registry analyzer that decomposes
# the registry into chains.  On this decomposed representation, provide
# strategies to draw chains, existing entries, non-existing entries,
# leaves, aliases, etc.
class TestSSHAgentSocketProviderRegistry:
    """Tests for the SSH agent socket provider registry."""

def test_resolve(
        self,
    ) -> None:
        """Resolving entries in the socket provider registry works."""
        registry = socketprovider.SocketProvider.registry
        resolve = socketprovider.SocketProvider.resolve
        lookup = socketprovider.SocketProvider.lookup
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setitem(
                registry, _types.BuiltinSSHAgentSocketProvider.STUB_AGENT, None
            )
            assert callable(
                lookup(_types.BuiltinSSHAgentSocketProvider.NATIVE)
            )
            assert callable(
                resolve(_types.BuiltinSSHAgentSocketProvider.NATIVE)
            )
            assert (
                lookup(_types.BuiltinSSHAgentSocketProvider.STUB_AGENT) is None
            )
            with pytest.raises(NotImplementedError):
                resolve(_types.BuiltinSSHAgentSocketProvider.STUB_AGENT)

@Parametrize.RESOLVE_CHAINS
    @hypothesis.given(
        terminal=strategies.sampled_from([
            "unimplemented",
            "alias",
            "callable",
        ]),
        chain=strategies.lists(
            strategies.sampled_from([
                "c1",
                "c2",
                "c3",
                "c4",
                "c5",
                "c6",
                "c7",
                "c8",
                "c9",
                "c10",
            ]),
            min_size=1,
            unique=True,
        ),
    )
    def test_resolve_chains(
        self,
        terminal: Literal["unimplemented", "alias", "callable"],
        chain: list[str],
    ) -> None:
        """Resolving a chain of providers works."""
        registry = socketprovider.SocketProvider.registry
        resolve = socketprovider.SocketProvider.resolve
        lookup = socketprovider.SocketProvider.lookup
        try:
            implementation = resolve(
                _types.BuiltinSSHAgentSocketProvider.NATIVE
            )
        except NotImplementedError:  # pragma: no cover
            hypothesis.note(f"{registry = }")
            pytest.fail("Native SSH agent socket provider is unavailable?!")
        # TODO(the-13th-letter): Rewrite using structural pattern matching.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        target: _types.SSHAgentSocketProvider | str | None = (
            None
            if terminal == "unimplemented"
            else _types.BuiltinSSHAgentSocketProvider.NATIVE
            if terminal == "alias"
            else implementation
        )
        with pytest.MonkeyPatch.context() as monkeypatch:
            for link in chain:
                monkeypatch.setitem(registry, link, target)
                target = link
            for link in chain:
                assert lookup(link) == (
                    implementation if terminal != "unimplemented" else None
                )
                if terminal == "unimplemented":
                    with pytest.raises(NotImplementedError):
                        resolve(link)
                else:
                    assert resolve(link) == implementation

# TODO(the-13th-letter): Reevaluate whether this makes sense as a
    # property-based test.
    @Parametrize.GOOD_ENTRY_POINTS
    def test_find_all_socket_providers(
        self,
        additional_entry_points: list[importlib.metadata.EntryPoint],
    ) -> None:
        """Finding all SSH agent socket providers works."""
        resolve = socketprovider.SocketProvider.resolve
        old_registry = socketprovider.SocketProvider.registry
        with pytest_machinery.faked_entry_point_list(
            additional_entry_points, remove_conflicting_entries=False
        ) as names:
            socketprovider.SocketProvider._find_all_ssh_agent_socket_providers()
            for name in names:
                assert name in socketprovider.SocketProvider.registry
                assert resolve(name) in {
                    callables.provider_entry_provider,
                    *old_registry.values(),
                }

# TODO(the-13th-letter): Reevaluate whether this makes sense as a
    # property-based test.
    @Parametrize.BAD_ENTRY_POINTS
    def test_find_all_socket_providers_errors(
        self,
        additional_entry_points: list[importlib.metadata.EntryPoint],
    ) -> None:
        """Finding faulty SSH agent socket providers raises errors."""
        with contextlib.ExitStack() as stack:
            stack.enter_context(
                pytest_machinery.faked_entry_point_list(
                    additional_entry_points, remove_conflicting_entries=False
                )
            )
            stack.enter_context(pytest.raises(AssertionError))
            socketprovider.SocketProvider._find_all_ssh_agent_socket_providers()

# TODO(the-13th-letter): Convert this to a property-based test once
    # the registry analyzer is ready.
    def test_overwriting_existing_entries(
        self,
    ) -> None:
        """The registry forbids incompatibly overwriting entries."""
        registry = socketprovider.SocketProvider.registry.copy()
        resolve = socketprovider.SocketProvider.resolve
        register = socketprovider.SocketProvider.register

def ancestry_chain(name: str) -> Generator[str, None, None]:
            current: _types.SSHAgentSocketProvider | str | None = name
            seen: set[_types.SSHAgentSocketProvider | str | None] = set()
            while isinstance(current, str) and current not in seen:
                yield current
                seen.add(current)
                current = registry[current]

# Entries with at least one level of alias resolving, and where each
        # entry ultimately resolves to a different provider.  They needn't
        # technically be leaves of the socket provider forest, but "leaves"
        # emphasizes the quality we are looking for.
        leaves = [
            _types.BuiltinSSHAgentSocketProvider.POSIX,
            _types.BuiltinSSHAgentSocketProvider.WINDOWS,
        ]
        assert all([isinstance(registry.get(leaf), str) for leaf in leaves]), (
            "Registry is shaped incompatibly; cannot determine base entries"
        )
        bases = [resolve(leaf) for leaf in leaves]
        names = [list(ancestry_chain(leaf)) for leaf in leaves]

with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", registry
            )
            # Registering names with different values is forbidden...
            with pytest.raises(ValueError, match="already registered"):
                register(names[0][0])(bases[1])
            with pytest.raises(ValueError, match="already registered"):
                register(names[1][0])(bases[0])
            # ...even if other names of the same registration are valid.
            with pytest.raises(ValueError, match="already registered"):
                register(names[0][0], names[1][1])(bases[0])
            with pytest.raises(ValueError, match="already registered"):
                register(names[1][0], names[0][1])(bases[1])

# TODO(the-13th-letter): Convert this to a property-based test once
    # the registry analyzer is ready.
    def test_resolve_non_existant_entries(
        self,
    ) -> None:
        """Resolving a non-existant entry fails."""
        new_registry = {
            _types.BuiltinSSHAgentSocketProvider.POSIX: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.POSIX
            ),
            _types.BuiltinSSHAgentSocketProvider.WINDOWS: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.WINDOWS
            ),
        }
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            with pytest.raises(socketprovider.NoSuchProviderError):
                socketprovider.SocketProvider.resolve(
                    _types.BuiltinSSHAgentSocketProvider.NATIVE
                )

# TODO(the-13th-letter): Convert this to a property-based test once
    # the registry analyzer is ready.
    def test_register_new_entry(
        self,
    ) -> None:
        """Registering new entries works."""

def socket_provider() -> _types.SSHAgentSocket:
            raise AssertionError

names = ["spam", "ham", "eggs", "parrot"]
        new_registry = {
            _types.BuiltinSSHAgentSocketProvider.POSIX: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.POSIX
            ),
            _types.BuiltinSSHAgentSocketProvider.WINDOWS: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.WINDOWS
            ),
        }
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            assert not any(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert (
                socketprovider.SocketProvider.register(*names)(socket_provider)
                is socket_provider
            )
            assert all(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert all([
                socketprovider.SocketProvider.resolve(n) is socket_provider
                for n in names
            ])

# TODO(the-13th-letter): Convert this to a property-based test once
    # the registry analyzer is ready.
    @Parametrize.EXISTING_REGISTRY_ENTRIES
    def test_register_old_entry(
        self,
        existing: str,
    ) -> None:
        """Registering old entries works."""

provider = socketprovider.SocketProvider.resolve(existing)
        new_registry = {
            _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_POSIX: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_POSIX
            ),
            _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_WINDOWS: socketprovider.SocketProvider.resolve(
                _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_WINDOWS
            ),
            _types.BuiltinSSHAgentSocketProvider.UNIX_DOMAIN: _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_POSIX,
            _types.BuiltinSSHAgentSocketProvider.WINDOWS_NAMED_PIPE: _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_WINDOWS,
        }
        names = [
            k
            for k, v in socketprovider.SocketProvider.registry.items()
            if v == existing
        ]
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(
                socketprovider.SocketProvider, "registry", new_registry
            )
            assert names, (
                f"Existing SSH agent socket provider entry "
                f"{existing!r} is not existing?!"
            )
            # TODO(the-13th-letter): Do we require, forbid, or not care
            # if `names` discovers aliases not present in the mocked
            # registry?  Currently, the "ssh_auth_sock" alias for
            # "ssh_auth_sock_on_posix" would be discovered, but
            # "ssh_auth_sock_on_windows" has no undiscovered aliases.
            #
            # assert not
            # all(map(socketprovider.SocketProvider.registry.__contains__,
            # names))
            assert (
                socketprovider.SocketProvider.register(existing, *names)(
                    provider
                )
                is provider
            )
            assert all(
                map(socketprovider.SocketProvider.registry.__contains__, names)
            )
            assert all([
                socketprovider.SocketProvider.resolve(n) is provider
                for n in [existing, *names]
            ])

class TestAgentSigning:
    """Test actually talking to the SSH agent: signing data."""

@Parametrize.ALL_SSH_TEST_KEYS
    def test_sign_data_via_agent(
        self,
        ssh_agent_client_with_test_keys_loaded: ssh_agent.SSHAgentClient,
        ssh_test_key_type: str,
        ssh_test_key: data.SSHTestKey,
    ) -> None:
        """Signing data with specific SSH keys works iff the key is suitable.

Single tests may abort early (skip) if the indicated key is not
        loaded in the agent.  Presumably this means the key type is
        unsupported.

"""
        client = ssh_agent_client_with_test_keys_loaded
        key_comment_pairs = {bytes(k): bytes(c) for k, c in client.list_keys()}
        public_key_data = ssh_test_key.public_key_data
        if public_key_data not in key_comment_pairs:  # pragma: no cover
            pytest.skip(f"prerequisite {ssh_test_key_type} SSH key not loaded")
        if ssh_test_key.is_suitable():
            assert (
                data.SSHTestKeyDeterministicSignatureClass.SPEC
                in ssh_test_key.expected_signatures
            )
            sig = ssh_test_key.expected_signatures[
                data.SSHTestKeyDeterministicSignatureClass.SPEC
            ]
            expected_signature = sig.signature
            derived_passphrase = sig.derived_passphrase
            signature = bytes(
                client.sign(payload=vault.Vault.UUID, key=public_key_data)
            )
            assert signature == expected_signature, (
                f"SSH signature mismatch ({ssh_test_key_type})"
            )
            signature2 = bytes(
                client.sign(payload=vault.Vault.UUID, key=public_key_data)
            )
            assert signature2 == expected_signature, (
                f"SSH signature mismatch ({ssh_test_key_type})"
            )
            assert (
                vault.Vault.phrase_from_key(public_key_data, conn=client)
                == derived_passphrase
            ), f"SSH signature mismatch ({ssh_test_key_type})"
        else:
            assert (
                data.SSHTestKeyDeterministicSignatureClass.SPEC
                not in ssh_test_key.expected_signatures
            )
            assert not vault.Vault.is_suitable_ssh_key(
                public_key_data, client=None
            ), f"Expected {ssh_test_key_type} key to be unsuitable in general"
            if vault.Vault.is_suitable_ssh_key(
                public_key_data, client=client
            ):  # pragma: no cover [external]
                potential_signatures = {
                    sig_class: sig.signature
                    for sig_class, sig in ssh_test_key.expected_signatures.items()
                    if sig_class
                    != data.SSHTestKeyDeterministicSignatureClass.SPEC
                }
                signature = bytes(
                    client.sign(payload=vault.Vault.UUID, key=public_key_data)
                )
                assert signature in potential_signatures.values()
            else:  # pragma: no cover [external]
                with pytest.raises(ValueError, match="unsuitable SSH key"):
                    vault.Vault.phrase_from_key(public_key_data, conn=client)

class TestSuitableKeys:
    """Test actually talking to the SSH agent: determining suitable keys."""

@Parametrize.SSH_KEY_SELECTION
    def test_ssh_key_selector(
        self,
        monkeypatch: pytest.MonkeyPatch,
        ssh_agent_client_with_test_keys_loaded: ssh_agent.SSHAgentClient,
        key: bytes,
        single: bool,
    ) -> None:
        """The key selector presents exactly the suitable keys.

"Suitable" here means suitability for this SSH agent
        specifically.

"""
        client = ssh_agent_client_with_test_keys_loaded

monkeypatch.setattr(
            ssh_agent.SSHAgentClient,
            "list_keys",
            callables.list_keys_singleton if single else callables.list_keys,
        )
        raw_keys_list = (
            callables.list_keys_singleton()
            if single
            else callables.list_keys()
        )
        keys = [
            pair.key
            for pair in raw_keys_list
            if vault.Vault.is_suitable_ssh_key(pair.key, client=client)
        ]
        n = len(keys)
        if single or n == 1:
            input_text = "yes\n"
            text = "Use this key? yes\n"
        else:
            input_text = f"{1 + keys.index(key)}\n"
            text = (
                f"Your selection? (1-{n}, leave empty to abort): {input_text}"
            )
        b64_key = base64.standard_b64encode(key).decode("ASCII")

@click.command()
        def driver() -> None:
            """Call [`cli_helpers.select_ssh_key`][] directly, as a command."""
            key = cli_helpers.select_ssh_key(
                client,
                error_callback=lambda s, *_args: pytest.fail(str(s)),
                warning_callback=lambda s, *_args: pytest.fail(str(s)),
            )
            click.echo(base64.standard_b64encode(key).decode("ASCII"))

runner = machinery.CliRunner(mix_stderr=True)
        result = runner.invoke(
            driver, [], input=input_text, catch_exceptions=True
        )
        for snippet in ("Suitable SSH keys:\n", text, f"\n{b64_key}\n"):
            assert result.clean_exit(output=snippet), "expected clean exit"

class TestConstructorFailures:
    """Test actually talking to the SSH agent: constructor failures."""

def test_constructor_bad_running_agent(
        self,
        running_ssh_agent: data.RunningSSHAgentInfo,
    ) -> None:
        """Fail if the agent address is invalid."""
        with pytest.MonkeyPatch.context() as monkeypatch:
            new_socket_name = (
                running_ssh_agent.socket + "~"
                if isinstance(running_ssh_agent.socket, str)
                else "<invalid//address>"
            )
            monkeypatch.setenv("SSH_AUTH_SOCK", new_socket_name)
            with pytest.raises(OSError):  # noqa: PT011
                ssh_agent.SSHAgentClient()

@Parametrize.MISSING_AGENT_SUPPORT
    def test_constructor_no_support(
        self,
        provider: _types.BuiltinSSHAgentSocketProvider,
        sys_action: data.SystemSupportAction,
        exception: type[NotImplementedError],
        message: str,
    ) -> None:
        """Fail without support for the communication technology."""
        del message
        assert provider in socketprovider.SocketProvider.registry
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setenv(
                "SSH_AUTH_SOCK", "the value doesn't even matter"
            )
            sys_action(monkeypatch)
            with pytest.raises(exception):
                ssh_agent.SSHAgentClient(socket=provider)

def test_no_ssh_agent_socket_provider_available(
        self,
    ) -> None:
        """Fail if no SSH agent socket provider is available."""
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setitem(
                socketprovider.SocketProvider.registry, "stub_agent", None
            )
            with pytest.raises(ExceptionGroup) as excinfo:
                ssh_agent.SSHAgentClient(
                    socket=["stub_agent", "stub_agent", "stub_agent"]
                )
            assert all([
                isinstance(e, NotImplementedError)
                for e in excinfo.value.exceptions
            ])

class TestOtherConstructorFeatures:
    """Test actually talking to the SSH agent: other constructor features."""

def test_explicit_socket(
        self,
        spawn_ssh_agent: data.SpawnedSSHAgentInfo,
    ) -> None:
        """The constructor accepts existing sockets."""
        conn = spawn_ssh_agent.client._connection
        ssh_agent.SSHAgentClient(socket=conn)

@pytest.mark.usefixtures("use_stub_agent")
class TestAgentErrorResponses:
    """Test actually talking to the SSH agent: errors from the SSH agent."""

@contextlib.contextmanager
    def _setup_agent_and_request_handler(
        self,
        request_responses_map: Mapping[
            data.AgentProtocolRequest, Sequence[data.AgentProtocolResponse]
        ],
        /,
    ) -> Generator[
        tuple[pytest.MonkeyPatch, ssh_agent.SSHAgentClient], None, None
    ]:
        # TODO(the-13th-letter): Rewrite using parenthesized
        # with-statements.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        with contextlib.ExitStack() as stack:
            monkeypatch = stack.enter_context(pytest.MonkeyPatch.context())
            client = stack.enter_context(
                ssh_agent.SSHAgentClient.ensure_agent_subcontext()
            )
            agent_io_queue = machinery.AgentProtocolResponseQueue(
                request_responses_map
            )
            stack.enter_context(agent_io_queue)
            monkeypatch.setattr(
                client,
                "_send_request_message",
                agent_io_queue._send_request_message,
            )
            monkeypatch.setattr(
                client, "_get_response_pair", agent_io_queue._get_response_pair
            )
            yield monkeypatch, client

@Parametrize.TRUNCATED_AGENT_RESPONSES
    def test_truncated_server_response(
        self,
        response: bytes,
    ) -> None:
        """Fail on truncated responses from the SSH agent."""
        client = ssh_agent.SSHAgentClient()
        agent = cast("machinery.StubbedSSHAgentSocket", client._connection)
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(agent, "send_to_client", bytearray(response))
            monkeypatch.setattr(agent, "sendall", lambda *_a, **_kw: None)
            with pytest.raises(EOFError):
                client.request(255, b"")

@Parametrize.LIST_KEYS_ERROR_RESPONSES
    def test_list_keys_error_responses(
        self,
        response_code: _types.SSH_AGENT,
        response: bytes | bytearray,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during key listing.

Known problems:

- The agent refuses, or otherwise indicates the operation
            failed.
          - The agent response is truncated.
          - The agent response is overlong.

"""
        with self._setup_agent_and_request_handler({
            data.AgentProtocolRequest(
                _types.SSH_AGENTC.REQUEST_IDENTITIES, b""
            ): [data.AgentProtocolResponse(response_code, bytes(response))],
        }) as contexts:
            _, client = contexts
            with pytest.raises(exc_type, match=exc_pattern):
                client.list_keys()

@Parametrize.SIGN_ERROR_RESPONSES
    def test_sign_error_responses(
        self,
        key: bytes | bytearray,
        check: bool,
        response_code: _types.SSH_AGENT,
        response: bytes | bytearray,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during signing.

Known problems:

- The key is not loaded into the agent.
          - The agent refuses, or otherwise indicates the operation
            failed.

"""
        Pair: TypeAlias = _types.SSHKeyCommentPair
        com = b"no comment"
        loaded_keys = [
            Pair(v.public_key_data, com).toreadonly()
            for v in data.SUPPORTED_KEYS.values()
        ]
        sign_payload = (
            ssh_agent.SSHAgentClient.string(key)
            + ssh_agent.SSHAgentClient.string(b"abc")
            + ssh_agent.SSHAgentClient.uint32(0)
        )
        with self._setup_agent_and_request_handler({
            data.AgentProtocolRequest(
                _types.SSH_AGENTC.SIGN_REQUEST, sign_payload
            ): [data.AgentProtocolResponse(response_code, bytes(response))],
        }) as contexts:
            monkeypatch, client = contexts
            monkeypatch.setattr(client, "list_keys", lambda: loaded_keys)
            with pytest.raises(exc_type, match=exc_pattern):
                client.sign(key, b"abc", check_if_key_loaded=check)

@Parametrize.REQUEST_ERROR_RESPONSES
    def test_request_error_responses(
        self,
        request_code: _types.SSH_AGENTC,
        response_code: _types.SSH_AGENT,
        exc_type: type[Exception],
        exc_pattern: str,
    ) -> None:
        """Fail on problems during signing.

Known problems:

- The key is not loaded into the agent.
          - The agent refuses, or otherwise indicates the operation
            failed.

"""
        # TODO(the-13th-letter): Rewrite using parenthesized
        # with-statements.
        # https://the13thletter.info/derivepassphrase/latest/pycompatibility/#after-eol-py3.9
        with contextlib.ExitStack() as stack:
            client = stack.enter_context(ssh_agent.SSHAgentClient())
            stack.enter_context(pytest.raises(exc_type, match=exc_pattern))
            client.request(request_code, b"", response_code=response_code)

@Parametrize.QUERY_EXTENSIONS_MALFORMED_RESPONSES
    def test_query_extensions_malformed_responses(
        self,
        response_data: bytes,
    ) -> None:
        """Fail on malformed responses while querying extensions."""
        with self._setup_agent_and_request_handler({
            data.AgentProtocolRequest(
                _types.SSH_AGENTC.EXTENSION,
                ssh_agent.SSHAgentClient.string(b"query"),
            ): [
                data.AgentProtocolResponse(
                    _types.SSH_AGENT.EXTENSION_RESPONSE, response_data
                )
            ],
        }) as contexts:
            _, client = contexts
            with pytest.raises(
                RuntimeError,
                match=r"Malformed response|does not match request",
            ):
                client.query_extensions()

def _query_response(
        self,
        /,
        *extensions: str,
        code: Literal[
            _types.SSH_AGENT.EXTENSION_RESPONSE, _types.SSH_AGENT.SUCCESS
        ] = _types.SSH_AGENT.EXTENSION_RESPONSE,
    ) -> data.AgentProtocolResponse:
        """Construct a response object from the given extensions.

Args:
            extensions:
                Names of extensions to advertise support for.
            code:
                The response code of the message.

Returns:
            An appropriately constructed response object.

"""
        payload = bytearray(b"\x00\x00\x00\x05query")
        for ext in extensions:
            payload.extend(TestStaticFunctionality.as_ssh_string(ext.encode()))
        return data.AgentProtocolResponse(code, bytes(payload))

IDENTITIES_REQUEST: Final = data.AgentProtocolRequest(
        _types.SSH_AGENTC.REQUEST_IDENTITIES, b""
    )
    IDENTITIES_RESPONSE: Final = data.AgentProtocolResponse(
        _types.SSH_AGENT.IDENTITIES_ANSWER, b"\x00\x00\x00\x00"
    )
    QUERY_REQUEST: Final = data.AgentProtocolRequest(
        _types.SSH_AGENTC.EXTENSION, b"\x00\x00\x00\x05query"
    )
    EXTRA_RESPONSE: Final = data.AgentProtocolResponse(
        _types.SSH_AGENT.SUCCESS, b""
    )

# TODO(the-13th-letter): Reconsider whether to parametrize or
    # hypothesize this test.
    @pytest.mark.parametrize(
        ["success_after_query", "extensions"],
        [
            pytest.param(
                False,
                data.AgentProtocolResponse(_types.SSH_AGENT.FAILURE, b""),
                id="openssh-10.2",
            ),
            pytest.param(
                True,
                data.AgentProtocolResponse(_types.SSH_AGENT.FAILURE, b""),
                id="openssh-10.2-mocked",
                marks=[
                    pytest.mark.xfail(
                        reason="specific to OpenSSH 10.3 output",
                        raises=AssertionError,
                        strict=True,
                    )
                ],
            ),
            pytest.param(
                False, ["session-bind@openssh.com"], id="openssh-fixed"
            ),
            pytest.param(
                True, ["session-bind@openssh.com"], id="openssh-10.3"
            ),
            pytest.param(
                False,
                [
                    "add-ppk@putty.projects.tartarus.org",
                    "reencrypt@putty.projects.tartarus.org",
                    "reencrypt-all@putty.projects.tartarus.org",
                    "list-extended@putty.projects.tartarus.org",
                ],
                id="pageant",
            ),
            pytest.param(
                True,
                [
                    "add-ppk@putty.projects.tartarus.org",
                    "reencrypt@putty.projects.tartarus.org",
                    "reencrypt-all@putty.projects.tartarus.org",
                    "list-extended@putty.projects.tartarus.org",
                ],
                id="pageant-mocked",
                marks=[
                    pytest.mark.xfail(
                        reason="specific to OpenSSH 10.3 output",
                        raises=AssertionError,
                        strict=True,
                    )
                ],
            ),
        ],
    )
    def test_tolerating_extra_success_after_extension_response(
        self,
        success_after_query: bool,
        extensions: list[str] | data.AgentProtocolResponse,
    ) -> None:
        """Tolerate an extra empty SUCCESS message from a "query" EXTENSION.

Specifically, in a "query"
        [`EXTENSION`][_types.SSH_AGENTC.EXTENSION] request, tolerate
        getting potentially both an
        [`EXTENSION_RESPONSE`][_types.SSH_AGENT.EXTENSION_RESPONSE] or
        [`SUCCESS`][_types.SSH_AGENT.SUCCESS] message and an additional
        empty [`SUCCESS`][_types.SSH_AGENT.SUCCESS] message afterwards,
        instead of only the first message.  This is spec-uncompliant
        behavior observed in `ssh-agent` from OpenSSH 10.3.  (And since
        then reported and acknowledged upstream, to be fixed in OpenSSH
        10.4: [OpenSSH Bug 3967][OPENSSH_BZ3967].)

[OPENSSH_BZ3967]: https://bugzilla.mindrot.org/show_bug.cgi?id=3967

"""
        query_response = (
            extensions
            if isinstance(extensions, data.AgentProtocolResponse)
            else self._query_response(*extensions)
        )
        request_responses_map = {
            self.IDENTITIES_REQUEST: [self.IDENTITIES_RESPONSE],
            self.QUERY_REQUEST: [query_response, self.EXTRA_RESPONSE]
            if success_after_query
            else [query_response],
        }
        with self._setup_agent_and_request_handler(
            request_responses_map
        ) as contexts:
            _, client = contexts
            client.query_extensions()

class TestSSHAgentSocketProviderFailures:
    """Test SSH agent socket provider-specific failures."""

def test_posix_provider_no_ssh_auth_sock(
        self,
        skip_if_no_af_unix_support: None,
    ) -> None:
        """For `posix`, fail if the running agent cannot be located."""
        del skip_if_no_af_unix_support
        provider = socketprovider.SocketProvider.resolve(
            _types.BuiltinSSHAgentSocketProvider.POSIX
        )
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.delenv("SSH_AUTH_SOCK", raising=False)
            with pytest.raises(
                KeyError, match="SSH_AUTH_SOCK environment variable"
            ):
                provider()

@hypothesis.given(named_pipe_name=Strategies.bad_named_pipe_names())
    def test_ssh_auth_sock_on_windows_provider_bad_named_pipe_name(
        self,
        named_pipe_name: str,
        skip_if_no_ctypes_windll_support: None,
    ) -> None:
        """For `ssh_auth_sock_on_windows`, fail for bad named pipe names."""
        del skip_if_no_ctypes_windll_support
        provider = socketprovider.SocketProvider.resolve(
            _types.BuiltinSSHAgentSocketProvider.SSH_AUTH_SOCK_ON_WINDOWS
        )
        with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setenv("SSH_AUTH_SOCK", named_pipe_name)
            with pytest.raises(ValueError, match="Invalid named pipe name"):
                provider()

class TestWindowsNamedPipeHandle:
    """Test the WindowsNamedPipeHandle wrapper class.

Even works on other operating systems, because the relevant parts
    are stubbed out anyway.

"""

DUMMY_ADDRESS = f"{socketprovider.PIPE_PREFIX}dummy-address"
    IO_ON_CLOSED_HANDLE_PATTERN = re.escape(
        socketprovider.WindowsNamedPipeHandle._IO_ON_CLOSED_FILE
    )

@hypothesis.given(named_pipe_name=Strategies.bad_named_pipe_names())
    def test_constructor_bad_named_pipe_name(
        self,
        named_pipe_name: str,
    ) -> None:
        """The constructor fails for bad named pipe names."""
        with pytest.raises(ValueError, match="Invalid named pipe name"):  # noqa: SIM117
            with socketprovider.WindowsNamedPipeHandle(named_pipe_name):
                pass

@contextlib.contextmanager
    def stub_createfile_and_closehandle(
        self,
    ) -> Generator[None, None, None]:
        singleton = object()

def create_file(*_args: Any, **_kwargs: Any) -> object:
            return singleton

def close_handle(*_args: Any, **_kwargs: Any) -> bool:
            return True

with pytest.MonkeyPatch.context() as monkeypatch:
            monkeypatch.setattr(socketprovider, "CreateFile", create_file)
            monkeypatch.setattr(socketprovider, "CloseHandle", close_handle)
            yield

@hypothesis.given(io_operation=Strategies.io_operations_on_handles())
    def test_closed_handle_cannot_be_operated_on(
        self,
        io_operation: Callable[[Any], Any],
    ) -> None:
        """Operating on a closed handle fails."""
        with self.stub_createfile_and_closehandle():
            handle = socketprovider.WindowsNamedPipeHandle(self.DUMMY_ADDRESS)
            with handle:
                pass  # close the handle
            with pytest.raises(
                ValueError, match=self.IO_ON_CLOSED_HANDLE_PATTERN
            ):
                io_operation(handle)

@hypothesis.given(io_operation=Strategies.io_operations_on_handles())
    def test_handle_is_non_reentrant(
        self,
        io_operation: Callable[[Any], Any],
    ) -> None:
        """The handler cannot be sensibly used in nested `with` blocks."""
        with self.stub_createfile_and_closehandle():
            handle = socketprovider.WindowsNamedPipeHandle(self.DUMMY_ADDRESS)
            with handle:
                with handle:
                    pass  # close the handle
                with pytest.raises(
                    ValueError, match=self.IO_ON_CLOSED_HANDLE_PATTERN
                ):
                    io_operation(handle)

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