Updates test_dataset to account for coverage

Author: chalmerlowe

tests/unit/test_dataset.py

@@ -1043,7 +1043,10 @@ def test_external_catalog_dataset_options_setter(self):
         expected = self.API_REPR
         assert result == expected
 
-    def test_external_catalog_dataset_options_getter(self):
+    # PATH A: prop is not None
+    def test_external_catalog_dataset_options_getter_prop_exists(self):
+        # GIVEN default dataset PLUS an ExternalCatalogDatasetOptions
+        # THEN confirm that external_catalog_dataset_options is set
         from google.cloud.bigquery.external_config import ExternalCatalogDatasetOptions
 
         dataset = self._make_one(self.DS_REF)
@@ -1057,6 +1060,15 @@ def test_external_catalog_dataset_options_getter(self):
 
         assert result == expected
 
+    def test_external_catalog_dataset_options_getter_prop_is_none(self):
+        # GIVEN only the default dataset
+        # THEN confirm that external_catalog_dataset_options is None
+        dataset = self._make_one(self.DS_REF)
+        expected = None
+        result = dataset.external_catalog_dataset_options
+
+        assert result == expected
+
     def test_external_catalog_dataset_options_from_api_repr(self):
         resource = self.API_REPR
         klass = self._get_target_class()