test(migrations): add downgrade tests; add codecov.yaml (#2)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nanotaboada

CHANGELOG.md

@@ -51,6 +51,10 @@ This project uses famous football coaches as release codenames, following an A-Z
   deterministic UUID v5 values); `alembic upgrade head` runs automatically on
   app startup via the lifespan handler (#2)
 - `alembic==1.18.4`, `asyncpg==0.31.0` added to dependencies (#2)
+- `tests/test_migrations.py`: integration tests for migration downgrade paths —
+  verifies each step removes only its seeded rows and restores correctly (#2)
+- `codecov.yaml`: excludes `alembic/env.py` from coverage (offline mode is
+  tooling infrastructure, not application logic) (#2)
 - `.sonarcloud.properties`: SonarCloud Automatic Analysis configuration —
   sources, tests, coverage exclusions aligned with `codecov.yml` (#554)
 - `.dockerignore`: added `.claude/`, `CLAUDE.md`, `.coderabbit.yaml`,

codecov.yaml

@@ -0,0 +1,11 @@
+coverage:
+  status:
+    patch:
+      default:
+        target: 80%
+    project:
+      default:
+        target: 80%
+
+ignore:
+  - "alembic/env.py"

tests/test_migrations.py

@@ -0,0 +1,64 @@
+"""
+Integration tests for Alembic migration downgrade paths.
+
+These tests exercise the downgrade() functions in each migration version,
+verifying that each step removes exactly the rows it seeded and leaves the
+rest of the database intact.
+
+Tests run after test_main.py (alphabetical order). Each test downgrades one
+or more steps, asserts the expected state, then restores to head before the
+next test, ensuring the shared SQLite database remains consistent for any
+subsequent test runs.
+"""
+
+import os
+import sqlite3
+
+from alembic import command
+from alembic.config import Config
+
+_DB_PATH = os.getenv("STORAGE_PATH", "./players-sqlite3.db")
+_ALEMBIC_CFG = Config("alembic.ini")
+
+
+def test_migration_downgrade_003_removes_substitutes_only():
+    """Downgrade 003→002 removes the 15 seeded substitutes, leaves Starting XI."""
+    command.downgrade(_ALEMBIC_CFG, "-1")
+
+    conn = sqlite3.connect(_DB_PATH)
+    total = conn.execute("SELECT COUNT(*) FROM players").fetchone()[0]
+    subs = conn.execute("SELECT COUNT(*) FROM players WHERE starting11=0").fetchone()[0]
+    conn.close()
+
+    command.upgrade(_ALEMBIC_CFG, "head")
+
+    assert total == 11
+    assert subs == 0
+
+
+def test_migration_downgrade_002_removes_starting11_only():
+    """Downgrade 002→001 removes the 11 seeded Starting XI, leaves table empty."""
+    command.downgrade(_ALEMBIC_CFG, "-2")
+
+    conn = sqlite3.connect(_DB_PATH)
+    total = conn.execute("SELECT COUNT(*) FROM players").fetchone()[0]
+    conn.close()
+
+    command.upgrade(_ALEMBIC_CFG, "head")
+
+    assert total == 0
+
+
+def test_migration_downgrade_001_drops_players_table():
+    """Downgrade 001→base drops the players table entirely."""
+    command.downgrade(_ALEMBIC_CFG, "base")
+
+    conn = sqlite3.connect(_DB_PATH)
+    table = conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name='players'"
+    ).fetchone()
+    conn.close()
+
+    command.upgrade(_ALEMBIC_CFG, "head")
+
+    assert table is None