Refactor database URL handling in Alembic environment

- Introduced a new function to normalize database URLs for Alembic, ensuring compatibility with different PostgreSQL drivers.
- Updated the `get_database_url` function to prioritize the use of the `TEST_DATABASE_URL` environment variable for CI and testing scenarios.
- Enhanced error messaging to clarify configuration requirements for database connections.

This change aims to improve the flexibility and reliability of database connections in the testing environment.

backend/alembic/env.py

@@ -18,9 +18,29 @@ logger = logging.getLogger(__name__)
 config = context.config
 
 
+def _normalize_alembic_sqlalchemy_url(url: str) -> str:
+    """Alembic usa el driver síncrono psycopg2; normaliza DSN típicos de app/tests."""
+    url = url.strip()
+    if url.startswith("postgresql+asyncpg://"):
+        return url.replace("postgresql+asyncpg://", "postgresql+psycopg2://", 1)
+    if url.startswith("postgresql+psycopg2://"):
+        return url
+    if url.startswith("postgresql://"):
+        return url.replace("postgresql://", "postgresql+psycopg2://", 1)
+    if url.startswith("postgres://"):
+        return url.replace("postgres://", "postgresql+psycopg2://", 1)
+    return url
+
+
 def get_database_url():
     """Obtiene la URL de la base de datos (PostgreSQL) desde variables de entorno o alembic.ini."""
-    # Intentar construir desde variables de entorno primero
+    # CI / pytest: misma URL que los tests (secret TEST_DATABASE_URL) o DATABASE_URL explícita
+    for env_key in ("TEST_DATABASE_URL"):
+        raw = os.environ.get(env_key)
+        if raw and raw.strip():
+            return _normalize_alembic_sqlalchemy_url(raw)
+
+    # Construcción desde settings (CORE_DB_* en .env / entorno)
     host = settings.CORE_DB_HOST
     db = settings.CORE_DB_NAME
     user = settings.CORE_DB_USER
@@ -41,7 +61,8 @@ def get_database_url():
     if not url:
         raise RuntimeError(
             "No se ha configurado la cadena de conexión a PostgreSQL. "
-            "Proporciona las variables de entorno POSTGRES_* o configura sqlalchemy.url en alembic.ini"
+            "Define TEST_DATABASE_URL o DATABASE_URL, o CORE_DB_HOST/CORE_DB_USER/CORE_DB_PASSWORD/CORE_DB_NAME, "
+            "o sqlalchemy.url en alembic.ini"
         )
 
     return url