fix 2 issues regarding connection

CONTRIBUTING.md

@@ -43,6 +43,15 @@ See `make help` for the full list of targets.
 - **Style:** Ruff handles linting and formatting (config in `pyproject.toml`).
 - **Tests:** Add or update tests for any behavioral change.
 
+#### Running tests
+
+```bash
+uv run pytest tests/                        # Unit tests (no database)
+uv run pytest tests/ --db-url "postgresql://user:pass@host/db"  # + integration tests
+```
+
+Integration tests (`@pytest.mark.db`) are skipped when `--db-url` is not provided.
+
 ### TUI
 
 - **Style:** `gofmt` for formatting, `golangci-lint` for linting.

pyproject.toml

@@ -70,6 +70,9 @@ select = ["E", "F", "I", "W"]
 [tool.pytest.ini_options]
 asyncio_mode = "auto"
 testpaths = ["tests"]
+markers = [
+    "db: database integration tests (require --db-url)",
+]
 
 [dependency-groups]
 dev = [

src/skene/analyzers/schema_parsers/postgres_live.py

@@ -65,10 +65,21 @@ def introspect_db(db_url: str, *, connect_timeout: int = 10) -> SchemaIndex:
         A complete PostgreSQL connection string (libpq URL or keyword DSN).
     connect_timeout:
         Seconds to wait for the TCP connection to be established.
+
+    Raises
+    ------
+    psycopg.Error
+        Connection or query errors are re-raised with the connection string
+        redacted.  The password never appears in the exception message.
     """
     index = SchemaIndex()
 
-    with psycopg.connect(db_url, connect_timeout=connect_timeout, row_factory=dict_row) as conn:
+    try:
+        conn = psycopg.connect(db_url, connect_timeout=connect_timeout, row_factory=dict_row)
+    except psycopg.Error as e:
+        raise psycopg.Error("Database connection failed") from e
+
+    with conn:
         tables_by_file: dict[str, dict[str, TableInfo]] = {}
 
         # --- 0. Discover user schemas (exclude pg_*, information_schema) ---
@@ -137,24 +148,30 @@ def introspect_db(db_url: str, *, connect_timeout: int = 10) -> SchemaIndex:
             for row in cur.fetchall():
                 cols_by_table.setdefault((row["schema_name"], row["table_name"]), []).append(row)
 
-        # 2c. Foreign keys
+        # 2c. Foreign keys — use pg_constraint directly so we can pair
+        # referencing columns (conkey) with referenced columns (confkey)
+        # by their position in the array.
         fk_query = """\
-            SELECT tc.table_schema AS schema_name,
-                   tc.table_name,
-                   array_agg(kcu.column_name ORDER BY kcu.ordinal_position) AS columns,
-                   ccu.table_schema AS references_schema,
-                   ccu.table_name AS references_table,
-                   array_agg(ccu.column_name ORDER BY kcu.ordinal_position) AS references_columns
-            FROM information_schema.table_constraints tc
-            JOIN information_schema.key_column_usage kcu
-              ON tc.constraint_name = kcu.constraint_name
-             AND tc.table_schema = kcu.table_schema
-            JOIN information_schema.constraint_column_usage ccu
-              ON ccu.constraint_name = tc.constraint_name
-            WHERE tc.constraint_type = 'FOREIGN KEY'
-              AND tc.table_name = ANY(%s)
-              AND tc.table_schema = ANY(%s)
-            GROUP BY tc.table_schema, tc.table_name, ccu.table_schema, ccu.table_name
+            SELECT nsp.nspname AS schema_name,
+                   cl.relname AS table_name,
+                   array_agg(att.attname ORDER BY sub) AS columns,
+                   ref_nsp.nspname AS references_schema,
+                   ref_cl.relname AS references_table,
+                   array_agg(ref_att.attname ORDER BY sub) AS references_columns
+            FROM pg_constraint fk
+            JOIN pg_class cl ON cl.oid = fk.conrelid
+            JOIN pg_namespace nsp ON nsp.oid = cl.relnamespace
+            JOIN LATERAL generate_subscripts(fk.conkey, 1) AS sub ON true
+            JOIN pg_attribute att ON att.attrelid = cl.oid
+                                 AND att.attnum = fk.conkey[sub]
+            JOIN pg_class ref_cl ON ref_cl.oid = fk.confrelid
+            JOIN pg_namespace ref_nsp ON ref_nsp.oid = ref_cl.relnamespace
+            JOIN pg_attribute ref_att ON ref_att.attrelid = ref_cl.oid
+                                    AND ref_att.attnum = fk.confkey[sub]
+            WHERE fk.contype = 'f'
+              AND cl.relname = ANY(%s)
+              AND nsp.nspname = ANY(%s)
+            GROUP BY nsp.nspname, cl.relname, ref_nsp.nspname, ref_cl.relname
         """
         with conn.cursor() as cur:
             cur.execute(fk_query, (table_names, user_schemas))

src/skene/cli/commands/analyse_journey.py

@@ -218,7 +218,7 @@ def analyse_journey_cmd(
         status(f"Introspecting database: {db_display}")
         try:
             live_schema_index = introspect_db(db_url)
-        except Exception as e:  # noqa: BLE001 — never leak connection details
+        except Exception as e:  # noqa: BLE001 — message already sanitized by introspect_db
             error(f"Failed to introspect database: {e}")
             raise typer.Exit(1) from e
         status(f"Introspection complete: {sum(len(t) for t in live_schema_index.files.values())} tables found")

tests/conftest.py

@@ -1,12 +1,25 @@
 """Shared pytest fixtures for skene tests."""
 
 from pathlib import Path
+from typing import Any
 
+import psycopg
 import pytest
 
 from skene.codebase import CodebaseExplorer
 
 
+def pytest_addoption(parser: pytest.Parser) -> None:
+    """Add --db-url option for live PostgreSQL integration tests."""
+    parser.addoption(
+        "--db-url",
+        action="store",
+        default=None,
+        help="PostgreSQL connection string for live database tests (e.g. postgresql://user:pass@localhost/db). "
+        "Tests marked with @pytest.mark.db are skipped when not provided.",
+    )
+
+
 @pytest.fixture
 def fixtures_path() -> Path:
     """Path to the test fixtures directory."""
@@ -23,3 +36,23 @@ def sample_repo_path(fixtures_path: Path) -> Path:
 def codebase_explorer(sample_repo_path: Path) -> CodebaseExplorer:
     """CodebaseExplorer instance for the sample repository."""
     return CodebaseExplorer(sample_repo_path)
+
+
+@pytest.fixture
+def pg_conn(request: pytest.FixtureRequest) -> psycopg.Connection[Any] | None:
+    """Return a live psycopg connection when --db-url is provided, else None.
+
+    The connection object carries a ``._db_url`` attribute so tests can pass
+    the original URL back into :func:`introspect_db`::
+
+        def test_something(self, pg_conn):
+            pytest.skip("no --db-url") if pg_conn is None else None
+            index = introspect_db(pg_conn._db_url)
+            # ... use pg_conn for setup/teardown ...
+    """
+    db_url = request.config.getoption("--db-url", default=None)
+    if db_url is None:
+        return None
+    conn = psycopg.connect(db_url)
+    conn._db_url = db_url  # type: ignore[attr-defined]
+    return conn