allow empty cloudfetch result

Signed-off-by: varun-edachali-dbx <varun.edachali@databricks.com>

Author: varun-edachali-dbx

src/databricks/sql/backend/sea/queue.py

@@ -74,13 +74,9 @@ def build_queue(
                 raise ValueError(
                     "SEA client is required for EXTERNAL_LINKS disposition"
                 )
-            if not result_data.external_links:
-                raise ValueError(
-                    "External links are required for EXTERNAL_LINKS disposition"
-                )
 
             return SeaCloudFetchQueue(
-                initial_links=result_data.external_links,
+                initial_links=result_data.external_links or [],
                 max_download_threads=max_download_threads,
                 ssl_options=ssl_options,
                 sea_client=sea_client,
@@ -163,7 +159,7 @@ def __init__(
 
         initial_link = next((l for l in initial_links if l.chunk_index == 0), None)
         if not initial_link:
-            raise ValueError("No initial link found for chunk index 0")
+            return
 
         self.download_manager = ResultFileDownloadManager(
             links=[],

tests/e2e/test_driver.py

@@ -368,7 +368,7 @@ def test_incorrect_query_throws_exception(self):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_create_table_will_return_empty_result_set(self, extra_params):
@@ -581,7 +581,7 @@ def test_get_catalogs(self):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_get_arrow(self, extra_params):
@@ -657,7 +657,7 @@ def execute_really_long_query():
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_can_execute_command_after_failure(self, extra_params):
@@ -682,7 +682,7 @@ def test_can_execute_command_after_failure(self, extra_params):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_can_execute_command_after_success(self, extra_params):
@@ -709,7 +709,7 @@ def generate_multi_row_query(self):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_fetchone(self, extra_params):
@@ -756,7 +756,7 @@ def test_fetchall(self, extra_params):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_fetchmany_when_stride_fits(self, extra_params):
@@ -779,7 +779,7 @@ def test_fetchmany_when_stride_fits(self, extra_params):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_fetchmany_in_excess(self, extra_params):
@@ -802,7 +802,7 @@ def test_fetchmany_in_excess(self, extra_params):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_iterator_api(self, extra_params):
@@ -890,7 +890,7 @@ def test_timestamps_arrow(self):
             },
             {
                 "use_sea": True,
-            }
+            },
         ],
     )
     def test_multi_timestamps_arrow(self, extra_params):