devx/tests/unit/test_start_docker.py

"""Unit tests for devx.molecule.start_docker."""

import os
from unittest.mock import MagicMock, mock_open, patch

from click.testing import CliRunner

from devx.molecule.start_docker import (
    DOCKER_SOCK,
    HOST_DOCKER_SOCK,
    ROOTLESS_SOCK,
    _diagnose_socket,
    _get_docker_free_bytes,
    _try_socket,
    is_docker_ready,
    main,
    start_docker_daemon,
)


class TestIsDockerReady:
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_ready(self, mock_run: MagicMock) -> None:
        mock_run.return_value = MagicMock(returncode=0)
        with patch.dict("os.environ", {"DOCKER_HOST": f"unix://{DOCKER_SOCK}"}, clear=False):
            assert is_docker_ready() is True
        call_kwargs = mock_run.call_args
        assert call_kwargs.args[0] == ["docker", "info"]
        assert call_kwargs.kwargs["env"]["DOCKER_HOST"] == f"unix://{DOCKER_SOCK}"

    @patch("devx.molecule.start_docker.subprocess.run")
    def test_not_ready(self, mock_run: MagicMock) -> None:
        mock_run.return_value = MagicMock(returncode=1)
        assert is_docker_ready() is False

    @patch("devx.molecule.start_docker.subprocess.run")
    def test_uses_docker_host_env(self, mock_run: MagicMock) -> None:
        """Should check the socket specified by DOCKER_HOST env var."""
        mock_run.return_value = MagicMock(returncode=0)
        rootless = "unix:///run/user/999/docker.sock"
        with patch.dict("os.environ", {"DOCKER_HOST": rootless}, clear=False):
            assert is_docker_ready() is True
        call_kwargs = mock_run.call_args
        assert call_kwargs.kwargs["env"]["DOCKER_HOST"] == rootless


class TestGetDockerFreeBytes:
    @patch("devx.molecule.start_docker.shutil.disk_usage")
    @patch("devx.molecule.start_docker.os.path.exists", return_value=True)
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_returns_free_bytes(self, mock_run: MagicMock, mock_exists: MagicMock, mock_du: MagicMock) -> None:
        mock_run.return_value = MagicMock(stdout="/var/lib/docker\n", returncode=0, text="")
        mock_du.return_value = MagicMock(free=50 * 1024**3)
        with patch.dict("os.environ", {"DOCKER_HOST": f"unix://{DOCKER_SOCK}"}, clear=False):
            assert _get_docker_free_bytes() == 50 * 1024**3

    @patch("devx.molecule.start_docker.subprocess.run")
    def test_daemon_not_reachable(self, mock_run: MagicMock) -> None:
        mock_run.return_value = MagicMock(returncode=1, stdout="", text="")
        assert _get_docker_free_bytes() == 0

    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_data_root_not_accessible(self, mock_run: MagicMock, mock_exists: MagicMock) -> None:
        mock_run.return_value = MagicMock(stdout="/some/path\n", returncode=0, text="")
        assert _get_docker_free_bytes() == 0

    @patch("devx.molecule.start_docker.subprocess.run", side_effect=FileNotFoundError)
    def test_subprocess_not_found(self, mock_run: MagicMock) -> None:
        assert _get_docker_free_bytes() == 0


class TestTrySocket:
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    def test_ready(self, mock_ready: MagicMock) -> None:
        assert _try_socket("/run/user/999/docker.sock") is True

    @patch("devx.molecule.start_docker.is_docker_ready", return_value=False)
    def test_not_ready(self, mock_ready: MagicMock) -> None:
        assert _try_socket("/run/user/999/docker.sock") is False


class TestDiagnoseSocket:
    @patch("devx.molecule.start_docker.os.stat")
    @patch("devx.molecule.start_docker.os.path.exists", return_value=True)
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_socket_exists(self, mock_run: MagicMock, mock_exists: MagicMock, mock_stat: MagicMock) -> None:
        mock_stat.return_value = MagicMock(st_mode=0o660, st_uid=0, st_gid=0)
        mock_run.side_effect = [
            MagicMock(stdout="/dev/sda1 /var/lib/docker ext4\n", returncode=0, text=""),
            MagicMock(stdout="default\n", returncode=0, text=""),
            MagicMock(
                stdout="Server Version: 29.5.2\nStorage Driver: overlay2\nDocker Root Dir: /var/lib/docker\n",
                returncode=0,
                text="",
            ),
        ]
        _diagnose_socket()
        mock_exists.assert_called_with(DOCKER_SOCK)

    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_socket_missing(self, mock_run: MagicMock, mock_exists: MagicMock) -> None:
        mock_run.side_effect = [
            MagicMock(stdout="proc on /proc type proc\n", returncode=0, text=""),
            MagicMock(stdout="default\n", returncode=0, text=""),
            MagicMock(stdout="", stderr="Cannot connect", returncode=1, text=""),
        ]
        _diagnose_socket()
        mock_exists.assert_called_with(DOCKER_SOCK)

    @patch("devx.molecule.start_docker.os.path.exists", return_value=True)
    @patch("devx.molecule.start_docker.os.stat")
    @patch("devx.molecule.start_docker.subprocess.run")
    def test_docker_info_no_matching_lines(
        self, mock_run: MagicMock, mock_stat: MagicMock, mock_exists: MagicMock
    ) -> None:
        """docker info succeeds but stdout has no Server Version/Storage Driver/Root Dir lines."""
        mock_stat.return_value = MagicMock(st_mode=0o660, st_uid=0, st_gid=0)
        mock_run.side_effect = [
            MagicMock(stdout="/dev/sda1 /var/lib/docker ext4\n", returncode=0, text=""),
            MagicMock(stdout="default\n", returncode=0, text=""),
            MagicMock(stdout="Containers: 0\nImages: 0\nKernel: 6.1\n", returncode=0, text=""),
        ]
        _diagnose_socket()
        mock_exists.assert_called_with(DOCKER_SOCK)


def _exists_map(paths: set[str]) -> MagicMock:
    """Return a mock os.path.exists that returns True only for *paths*."""
    return MagicMock(side_effect=lambda p: p in paths)


class TestStartDockerDaemon:
    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=100 * 1024**3)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_host_socket_available_with_space(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should return immediately if /var/run/docker.sock has enough space."""
        assert start_docker_daemon(timeout=5) is True
        mock_diag.assert_called_once()

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({HOST_DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_host_rootless_inaccessible_root_uses_host(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should use host rootless Docker when root dir is inaccessible (free=0)."""
        assert start_docker_daemon(timeout=5) is True

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    @patch("devx.molecule.start_docker.time.sleep")
    def test_inner_dockerd_free_zero_starts_local(
        self,
        mock_sleep: MagicMock,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Inner dockerd with free=0 (not host socket) should NOT be trusted — start local."""
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        # is_docker_ready: first check (inner dockerd) True, then local daemon checks
        mock_ready.side_effect = [True, False, False, False, False, True]
        assert start_docker_daemon(timeout=5) is True
        mock_popen.assert_called_once()

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes")
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    @patch("devx.molecule.start_docker.time.sleep")
    def test_host_socket_low_space_starts_local(
        self,
        mock_sleep: MagicMock,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should start local dockerd if host Docker has low space and no rootless sockets."""
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        mock_ready.side_effect = [True, False, False, False, False, True]
        mock_free.return_value = 5 * 1024**3
        # mock_run: pkill calls (x2), docker info check (returncode=1 = dead), rm call
        mock_run.side_effect = [
            MagicMock(),
            MagicMock(),
            MagicMock(returncode=1),
            MagicMock(),
        ]
        assert start_docker_daemon(timeout=5) is True
        mock_popen.assert_called_once()

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes")
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    @patch("devx.molecule.start_docker.time.sleep")
    def test_inner_dockerd_alive_uses_alt_sock(
        self,
        mock_sleep: MagicMock,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should use /dev/shm/docker.sock if inner dockerd can't be killed."""
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        mock_ready.side_effect = [True, False, False, False, False, True]
        mock_free.return_value = 5 * 1024**3
        # mock_run: pkill calls (x2), docker info check (returncode=0 = alive), rm call
        mock_run.side_effect = [
            MagicMock(),
            MagicMock(),
            MagicMock(returncode=0),
            MagicMock(),
        ]
        assert start_docker_daemon(timeout=5) is True
        mock_popen.assert_called_once()
        assert os.environ.get("DOCKER_HOST") == "unix:///dev/shm/docker.sock"

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes")
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK, HOST_DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_host_rootless_preferred_over_inner_dockerd(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should prefer /run/host-docker.sock over /var/run/docker.sock."""
        # host rootless ready with space, inner dockerd never tried
        mock_ready.side_effect = [True]
        mock_free.side_effect = [200 * 1024**3]
        assert start_docker_daemon(timeout=5) is True
        # DOCKER_HOST should be set to host socket
        assert os.environ.get("DOCKER_HOST") == f"unix://{HOST_DOCKER_SOCK}"

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=100 * 1024**3)
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK, HOST_DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_host_rootless_not_ready_falls_to_inner(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should fall through to inner dockerd if host rootless socket is not ready."""
        mock_ready.side_effect = [False, True]
        assert start_docker_daemon(timeout=5) is True
        assert os.environ.get("DOCKER_HOST") == f"unix://{DOCKER_SOCK}"

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=100 * 1024**3)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    @patch(
        "devx.molecule.start_docker.os.path.exists",
        side_effect=_exists_map({DOCKER_SOCK, HOST_DOCKER_SOCK, ROOTLESS_SOCK, "/run/user/999/docker.sock"}),
    )
    @patch("devx.molecule.start_docker.glob.glob", return_value=["/run/user/999/docker.sock"])
    def test_glob_finds_extra_rootless_socket(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should include rootless sockets found via glob scan."""
        assert start_docker_daemon(timeout=5) is True

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes")
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK, HOST_DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_inner_dockerd_fallback_when_host_rootless_low_space(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should fall back to inner dockerd if host rootless has low space."""
        # host rootless ready low space, inner dockerd ready with space
        mock_ready.side_effect = [True, True]
        mock_free.side_effect = [5 * 1024**3, 200 * 1024**3]
        assert start_docker_daemon(timeout=5) is True
        assert os.environ.get("DOCKER_HOST") == f"unix://{DOCKER_SOCK}"

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes")
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    @patch("devx.molecule.start_docker.time.sleep")
    def test_all_sockets_low_space_starts_local(
        self,
        mock_sleep: MagicMock,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """Should start local dockerd if all sockets have low space."""
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        mock_ready.side_effect = [True, False, False, False, False, True]
        mock_free.return_value = 5 * 1024**3
        assert start_docker_daemon(timeout=5) is True
        mock_popen.assert_called_once()

    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=False)
    @patch("devx.molecule.start_docker.time.sleep")
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    def test_starts_local_daemon(
        self,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_sleep: MagicMock,
        mock_ready: MagicMock,
        mock_exists: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
        mock_glob: MagicMock,
    ) -> None:
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        # No sockets exist, local daemon starts
        mock_ready.side_effect = [False, False, False, False, True]
        assert start_docker_daemon(timeout=5) is True
        mock_popen.assert_called_once()
        popen_args = mock_popen.call_args.args[0]
        assert "dockerd" in popen_args
        assert "--storage-driver" in popen_args
        assert "vfs" in popen_args
        assert "-H" in popen_args

    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=False)
    @patch("devx.molecule.start_docker.time.sleep")
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    def test_fails_after_timeout(
        self,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_sleep: MagicMock,
        mock_ready: MagicMock,
        mock_exists: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
        mock_glob: MagicMock,
    ) -> None:
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        with patch("builtins.open", mock_open(read_data="dockerd error log")):
            assert start_docker_daemon(timeout=3) is False
        mock_popen.assert_called_once()
        assert mock_sleep.call_count == 4  # 1 after pkill + 3 timeout retries

    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=False)
    @patch("devx.molecule.start_docker.time.sleep")
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    def test_fails_log_read_error(
        self,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_sleep: MagicMock,
        mock_ready: MagicMock,
        mock_exists: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
        mock_glob: MagicMock,
    ) -> None:
        """Should handle log read errors gracefully."""
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        with patch("builtins.open", side_effect=OSError("permission denied")):
            assert start_docker_daemon(timeout=2) is False

    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=0)
    @patch("devx.molecule.start_docker.os.path.exists", return_value=False)
    @patch("devx.molecule.start_docker.is_docker_ready")
    @patch("devx.molecule.start_docker.time.sleep")
    @patch("devx.molecule.start_docker.subprocess.run")
    @patch("devx.molecule.start_docker.subprocess.Popen")
    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
    def test_local_daemon_ready_on_first_check(
        self,
        mock_ntf: MagicMock,
        mock_popen: MagicMock,
        mock_run: MagicMock,
        mock_sleep: MagicMock,
        mock_ready: MagicMock,
        mock_exists: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
        mock_glob: MagicMock,
    ) -> None:
        mock_ntf.return_value = MagicMock(name="/tmp/dockerd.log")
        # No sockets exist, local ready on second loop check
        mock_ready.side_effect = [False, False, True]
        assert start_docker_daemon(timeout=5) is True
        assert mock_popen.call_count == 1
        assert mock_sleep.call_count == 3  # 1 after pkill + 2 loop retries

    @patch("devx.molecule.start_docker._diagnose_socket")
    @patch("devx.molecule.start_docker._get_docker_free_bytes", return_value=100 * 1024**3)
    @patch("devx.molecule.start_docker.os.environ")
    @patch("devx.molecule.start_docker.is_docker_ready", return_value=True)
    @patch("devx.molecule.start_docker.os.path.exists", side_effect=_exists_map({DOCKER_SOCK}))
    @patch("devx.molecule.start_docker.glob.glob", return_value=[])
    def test_sets_docker_host(
        self,
        mock_glob: MagicMock,
        mock_exists: MagicMock,
        mock_ready: MagicMock,
        mock_environ: MagicMock,
        mock_free: MagicMock,
        mock_diag: MagicMock,
    ) -> None:
        """DOCKER_HOST must be set so molecule connects to correct socket."""
        start_docker_daemon(timeout=5)
        mock_environ.__setitem__.assert_called_with("DOCKER_HOST", f"unix://{DOCKER_SOCK}")


class TestMain:
    @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)
    def test_success(self, mock_start: MagicMock) -> None:
        runner = CliRunner()
        result = runner.invoke(main, [])
        assert result.exit_code == 0

    @patch("devx.molecule.start_docker.start_docker_daemon", return_value=False)
    def test_failure(self, mock_start: MagicMock) -> None:
        runner = CliRunner()
        result = runner.invoke(main, [])
        assert result.exit_code == 1

    @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)
    def test_custom_timeout_flag(self, mock_start: MagicMock) -> None:
        runner = CliRunner()
        result = runner.invoke(main, ["--timeout", "60"])
        assert result.exit_code == 0
        mock_start.assert_called_once_with(60)

    @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)
    def test_exports_github_env(self, mock_start: MagicMock) -> None:
        """Should write DOCKER_HOST to GITHUB_ENV when available."""
        env = {"GITHUB_ENV": "/tmp/github_env", "DOCKER_HOST": f"unix://{DOCKER_SOCK}"}
        with patch.dict("os.environ", env, clear=True):
            with patch("builtins.open", mock_open()) as mock_file:
                runner = CliRunner()
                result = runner.invoke(main, [])
                assert result.exit_code == 0
                mock_file.assert_called_with("/tmp/github_env", "a", encoding="utf-8")

    @patch("devx.molecule.start_docker.os.environ.get", return_value="")
    @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)
    def test_no_github_env(self, mock_start: MagicMock, mock_get: MagicMock) -> None:
        """Should not crash when GITHUB_ENV is not set."""
        runner = CliRunner()
        result = runner.invoke(main, [])
        assert result.exit_code == 0