From 5d3abbb3485601fffab06ed3faa23a20579b5c7c Mon Sep 17 00:00:00 2001
From: Jiashen Cao <caojiashen24@gmail.com>
Date: Wed, 30 Aug 2023 12:17:26 -0400
Subject: [PATCH] fix: improve error msg (#997)

---
 evadb/executor/use_executor.py                |  5 +++
 .../short/test_use_executor.py                | 43 +++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 test/integration_tests/short/test_use_executor.py

diff --git a/evadb/executor/use_executor.py b/evadb/executor/use_executor.py
index f8f66df7a..dd1a94448 100644
--- a/evadb/executor/use_executor.py
+++ b/evadb/executor/use_executor.py
@@ -33,6 +33,11 @@ def exec(self, *args, **kwargs) -> Iterator[Batch]:
             self._database_name
         )
 
+        if db_catalog_entry is None:
+            raise ExecutorError(
+                f"{self._database_name} data source does not exist. Use CREATE DATABASE to add a new data source."
+            )
+
         handler = get_database_handler(
             db_catalog_entry.engine,
             **db_catalog_entry.params,
diff --git a/test/integration_tests/short/test_use_executor.py b/test/integration_tests/short/test_use_executor.py
new file mode 100644
index 000000000..6f941e248
--- /dev/null
+++ b/test/integration_tests/short/test_use_executor.py
@@ -0,0 +1,43 @@
+# coding=utf-8
+# Copyright 2018-2023 EvaDB
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import unittest
+from test.util import get_evadb_for_testing, shutdown_ray
+
+from evadb.executor.executor_utils import ExecutorError
+from evadb.server.command_handler import execute_query_fetch_all
+
+
+class CreateDatabaseTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.evadb = get_evadb_for_testing()
+        # reset the catalog manager before running each test
+        cls.evadb.catalog().reset()
+
+    @classmethod
+    def tearDownClass(cls):
+        shutdown_ray()
+
+    def test_use_should_raise_executor_error(self):
+        query = """USE not_available_ds {
+            SELECT * FROM table
+        }"""
+
+        with self.assertRaises(ExecutorError):
+            execute_query_fetch_all(self.evadb, query)
+
+
+if __name__ == "__main__":
+    unittest.main()