feat: exit code breakdown + PostgreSQL CI (#8)

mrt check exit codes (breaking change, ESLint convention):
  0 = no issues
  1 = warnings only (previously exit 0 without --strict)
  2 = errors found (previously exit 1)
  2 = warnings + --strict (previously exit 1)

Why: CI scripts can now distinguish must-fix (2) from should-review (1)
  if mrt check; then deploy; fi          → still works (0 = success)
  if [ $? -eq 2 ]; then block_merge; fi → errors only
  if [ $? -ge 1 ]; then notify; fi      → any issue

PostgreSQL CI (new test-postgres job):
  - Runs postgres:16 service container
  - tests/test_postgres.py: 4 integration tests
    - reversible migration on PG
    - noop downgrade detection on PG
    - SmartSeeder insert+verify on PG (NullPool + quoting)
    - check_all() 2-migration chain on PG
  - Skips gracefully when TEST_DATABASE_URL not set (local dev)
  - SQLite job ignores test_postgres.py to avoid duplication

Author: croc100

.github/workflows/ci.yml

@@ -46,7 +46,7 @@ jobs:
         run: pip install -e ".[dev]" coverage
 
       - name: Run tests
-        run: coverage run -m pytest tests/ -v
+        run: coverage run -m pytest tests/ -v --ignore=tests/test_postgres.py
 
       - name: Generate coverage report
         run: coverage xml
@@ -59,3 +59,36 @@ jobs:
           files: coverage.xml
           flags: unittests
           fail_ci_if_error: false
+
+  test-postgres:
+    runs-on: ubuntu-latest
+
+    services:
+      postgres:
+        image: postgres:16
+        env:
+          POSTGRES_USER: mrt
+          POSTGRES_PASSWORD: mrt
+          POSTGRES_DB: mrt_test
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          - 5432:5432
+
+    steps:
+      - uses: actions/checkout@v5
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: "3.13"
+
+      - name: Install
+        run: pip install -e ".[dev,postgres]" coverage
+
+      - name: Run PostgreSQL tests
+        env:
+          TEST_DATABASE_URL: postgresql://mrt:mrt@localhost:5432/mrt_test
+        run: coverage run -m pytest tests/test_postgres.py -v

pytest_mrt/cli.py

@@ -42,7 +42,7 @@ def version_cmd() -> None:
 @app.command("check")
 def check(
     versions_dir: str = typer.Argument(help="Path to Alembic versions directory"),
-    strict: bool = typer.Option(False, "--strict", help="Exit 1 on warnings too"),
+    strict: bool = typer.Option(False, "--strict", help="Treat warnings as errors (exit 2)"),
     fmt: str = typer.Option("table", "--format", "-f", help="Output format: table | json"),
 ) -> None:
     """Statically analyze migrations for rollback risk patterns (Alembic and Django)."""
@@ -75,7 +75,12 @@ def check(
         ]
         sys.stdout.write(json.dumps(output, indent=2) + "\n")
         has_errors = any(w.severity == "error" for w in warnings)
-        raise typer.Exit(1 if has_errors or (strict and warnings) else 0)
+        has_warns = any(w.severity == "warning" for w in warnings)
+        if has_errors or (strict and has_warns):
+            raise typer.Exit(2)
+        if has_warns:
+            raise typer.Exit(1)
+        raise typer.Exit(0)
 
     if not warnings:
         console.print("[green]✓ No rollback risks detected.[/green]")
@@ -103,13 +108,13 @@ def check(
         console.print(
             f"[red]{len(errors)} error(s)[/red], [yellow]{len(warns)} warning(s)[/yellow]"
         )
-        raise typer.Exit(1)
+        raise typer.Exit(2)
     elif warns and strict:
-        console.print(f"[yellow]{len(warns)} warning(s)[/yellow] (--strict mode)")
-        raise typer.Exit(1)
+        console.print(f"[yellow]{len(warns)} warning(s)[/yellow] (--strict: treated as errors)")
+        raise typer.Exit(2)
     else:
         console.print(f"[yellow]{len(warns)} warning(s)[/yellow] — review before deploying")
-        raise typer.Exit(0)
+        raise typer.Exit(1)
 
 
 # ──────────────────────────────────────────────

tests/test_cli.py

@@ -73,10 +73,10 @@ def test_check_safe_migrations_exits_0(tmp_path, versions_dir):
     assert "No rollback risks" in result.output
 
 
-def test_check_risky_migration_exits_1(tmp_path, versions_dir):
+def test_check_risky_migration_exits_2(tmp_path, versions_dir):
     _risky_migration(versions_dir)
     result = runner.invoke(app, ["check", str(versions_dir)])
-    assert result.exit_code == 1
+    assert result.exit_code == 2
 
 
 def test_check_shows_pattern_name(tmp_path, versions_dir):
@@ -102,6 +102,7 @@ def test_check_json_format(tmp_path, versions_dir):
     assert len(data) > 0
     assert "pattern" in data[0]
     assert "severity" in data[0]
+    assert result.exit_code == 2  # errors → exit 2
 
 
 def test_check_json_safe_exits_0(tmp_path, versions_dir):
@@ -126,8 +127,9 @@ def downgrade():
     """))
     result_normal = runner.invoke(app, ["check", str(versions_dir)])
     result_strict = runner.invoke(app, ["check", str(versions_dir), "--strict"])
-    # strict mode should exit 1 when there are warnings
-    assert result_strict.exit_code >= result_normal.exit_code
+    # warnings only: exit 1 normally, exit 2 with --strict
+    assert result_normal.exit_code == 1
+    assert result_strict.exit_code == 2
 
 
 def test_check_detects_django_migrations(tmp_path):