Fix python Cloud Spanner tests. [(#1548)](GoogleCloudPlatform/python-docs-samples#1548)

* Fix python Cloud Spanner tests.
* Lint.

Author: jsimonweb

samples/samples/snippets_test.py

@@ -51,6 +51,20 @@ def temporary_database(spanner_instance):
     database_id = unique_database_id()
     snippets.create_database(SPANNER_INSTANCE, database_id)
     snippets.insert_data(SPANNER_INSTANCE, database_id)
+    snippets.write_struct_data(SPANNER_INSTANCE, database_id)
+    database = spanner_instance.database(database_id)
+    database.reload()
+    yield database
+    database.drop()
+
+
+@pytest.fixture(scope='module')
+def temporary_database_with_all_columns(spanner_instance):
+    database_id = unique_database_id()
+    snippets.create_database(SPANNER_INSTANCE, database_id)
+    snippets.insert_data(SPANNER_INSTANCE, database_id)
+    snippets.add_column(SPANNER_INSTANCE, database_id)
+    snippets.add_timestamp_column(SPANNER_INSTANCE, database_id)
     database = spanner_instance.database(database_id)
     database.reload()
     yield database
@@ -213,10 +227,11 @@ def test_add_timestamp_column(temporary_database, capsys):
 
 
 @pytest.mark.slow
-def test_update_data_with_timestamp(temporary_database, capsys):
+def test_update_data_with_timestamp(temporary_database_with_all_columns,
+                                    capsys):
     snippets.update_data_with_timestamp(
         SPANNER_INSTANCE,
-        temporary_database.database_id)
+        temporary_database_with_all_columns.database_id)
 
     out, _ = capsys.readouterr()