test: cover invalid cli env vars

Author: Henry Lee

src/mcp/cli/cli.py

@@ -53,7 +53,7 @@ def _get_npx_command():
     return "npx"  # On Unix-like systems, just use npx
 
 
-def _parse_env_var(env_var: str) -> tuple[str, str]:  # pragma: no cover
+def _parse_env_var(env_var: str) -> tuple[str, str]:
     """Parse environment variable string in format KEY=VALUE."""
     if "=" not in env_var:
         logger.error(f"Invalid environment variable format: {env_var}. Must be KEY=VALUE")

tests/cli/test_utils.py

@@ -86,6 +86,14 @@ def test_collect_env_vars_from_cli_values():
     assert _collect_env_vars(None, ["API_KEY=abc123", "EMPTY="]) == {"API_KEY": "abc123", "EMPTY": ""}
 
 
+def test_collect_env_vars_exits_on_invalid_cli_value():
+    """CLI env vars must use KEY=VALUE format."""
+    with pytest.raises(SystemExit) as exc_info:
+        _collect_env_vars(None, ["API_KEY"])
+
+    assert exc_info.value.code == 1
+
+
 def test_collect_env_vars_file_then_cli_override(monkeypatch: pytest.MonkeyPatch, tmp_path: Path):
     """CLI env vars should override values loaded from a .env file."""
     env_file = tmp_path / ".env"