DEVX-24: fix: use separate Docker socket for DinD in CI

tests/unit/test_start_docker.py

@@ -4,7 +4,7 @@ from unittest.mock import MagicMock, patch
 
 from click.testing import CliRunner
 
-from devx.molecule.start_docker import is_docker_ready, main, start_docker_daemon
+from devx.molecule.start_docker import DOCKER_SOCK, is_docker_ready, main, start_docker_daemon
 
 
 class TestIsDockerReady:
@@ -12,7 +12,9 @@ class TestIsDockerReady:
     def test_ready(self, mock_run: MagicMock) -> None:
         mock_run.return_value = MagicMock(returncode=0)
         assert is_docker_ready() is True
-        mock_run.assert_called_once_with(["docker", "info"], capture_output=True, check=False)
+        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:
@@ -33,10 +35,15 @@ class TestStartDockerDaemon:
         mock_sleep: MagicMock,
     ) -> None:
         mock_ntf.return_value = MagicMock()
-        # First loop iteration: dockerd not ready yet. Second: ready.
         mock_ready.side_effect = [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
+        assert f"unix://{DOCKER_SOCK}" in popen_args
         mock_sleep.assert_called_once_with(1)
 
     @patch("devx.molecule.start_docker.time.sleep")
@@ -84,11 +91,29 @@ class TestStartDockerDaemon:
         mock_sleep: MagicMock,
     ) -> None:
         mock_ntf.return_value = MagicMock()
-        # 9 iterations not ready, 10th ready.
         mock_ready.side_effect = [False] * 9 + [True]
         assert start_docker_daemon(timeout=10) is True
         assert mock_sleep.call_count == 9
 
+    @patch("devx.molecule.start_docker.os.environ")
+    @patch("devx.molecule.start_docker.time.sleep")
+    @patch("devx.molecule.start_docker.is_docker_ready")
+    @patch("devx.molecule.start_docker.subprocess.Popen")
+    @patch("devx.molecule.start_docker.tempfile.NamedTemporaryFile")
+    def test_sets_docker_host(
+        self,
+        mock_ntf: MagicMock,
+        mock_popen: MagicMock,
+        mock_ready: MagicMock,
+        mock_sleep: MagicMock,
+        mock_environ: MagicMock,
+    ) -> None:
+        """DOCKER_HOST must be set so molecule connects to local daemon."""
+        mock_ntf.return_value = MagicMock()
+        mock_ready.return_value = True
+        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)