test: add provider postgres conformance

src/user_engine/adapters/postgres.py

@@ -90,9 +90,9 @@ class PostgresUserEngineStore:
         return self.schema_version == LATEST_SCHEMA_VERSION
 
     def migrate(self) -> None:
-        sql = _load_bootstrap_sql()
         with self._cursor() as cursor:
-            cursor.execute(sql)
+            for statement in _bootstrap_sql_statements():
+                cursor.execute(statement)
         self.connection.commit()
 
     @contextmanager
@@ -549,16 +549,20 @@ class PostgresUserEngineStore:
         )
 
     def _has_latest_schema(self) -> bool:
-        with self._cursor() as cursor:
-            cursor.execute(
-                """
-                SELECT 1
-                FROM user_engine_schema_versions
-                WHERE version = %s
-                """,
-                (LATEST_SCHEMA_VERSION,),
-            )
-            return cursor.fetchone() is not None
+        try:
+            with self._cursor() as cursor:
+                cursor.execute(
+                    """
+                    SELECT 1
+                    FROM user_engine_schema_versions
+                    WHERE version = %s
+                    """,
+                    (LATEST_SCHEMA_VERSION,),
+                )
+                return cursor.fetchone() is not None
+        except Exception:
+            self.connection.rollback()
+            return False
 
     @contextmanager
     def _cursor(self) -> Iterator[PostgresCursor]:
@@ -624,3 +628,11 @@ def _load_bootstrap_sql() -> str:
     return (repo_root / "migrations/postgres/0001_user_engine_store.sql").read_text(
         encoding="utf-8"
     )
+
+
+def _bootstrap_sql_statements() -> tuple[str, ...]:
+    return tuple(
+        f"{statement.strip()};"
+        for statement in _load_bootstrap_sql().split(";")
+        if statement.strip()
+    )