feat: add get_default_engine method for the database (#197)

Co-authored-by: Eric Ford <[email protected]>

Author: yuryfirebolt

src/firebolt/model/database.py

@@ -164,3 +164,16 @@ class _DatabaseUpdateRequest(FireboltBaseModel):
         return Database.parse_obj_with_service(
             response.json()["database"], self._service
         )
+
+    def get_default_engine(self) -> Optional[Engine]:
+        """
+        Returns: default engine of the database, or None if default engine is missing
+        """
+        rm = self._service.resource_manager
+        default_engines = [
+            rm.engines.get(binding.engine_id)
+            for binding in rm.bindings.get_many(database_id=self.database_id)
+            if binding.is_default_engine
+        ]
+
+        return None if len(default_engines) == 0 else default_engines[0]

tests/integration/resource_manager/test_database.py

@@ -0,0 +1,23 @@
+from firebolt.common import Settings
+from firebolt.service.manager import ResourceManager
+
+
+def test_database_get_default_engine(
+    rm_settings: Settings,
+    database_name: str,
+    stopped_engine_name: str,
+    engine_name: str,
+):
+    """
+    Checks that the default engine is either running or stopped engine
+    """
+    rm = ResourceManager(rm_settings)
+
+    db = rm.databases.get_by_name(database_name)
+
+    engine = db.get_default_engine()
+    assert engine is not None, "default engine is None, but shouldn't"
+    assert engine.name in [
+        stopped_engine_name,
+        engine_name,
+    ], "Returned default engine name is neither of known engines"