tests: fix flaky systest (#232)

Avoid sharing dataset ids between separate test cases.

Author: HemangChothani

tests/system.py

@@ -422,7 +422,7 @@ def test_create_table_w_time_partitioning_w_clustering_fields(self):
  self.assertEqual(table.clustering_fields, ["user_email", "store_code"])
 
  def test_delete_dataset_with_string(self):
- dataset_id = _make_dataset_id("delete_table_true")
+ dataset_id = _make_dataset_id("delete_table_true_with_string")
  project = Config.CLIENT.project
  dataset_ref = bigquery.DatasetReference(project, dataset_id)
  retry_403(Config.CLIENT.create_dataset)(Dataset(dataset_ref))
@@ -431,7 +431,7 @@ def test_delete_dataset_with_string(self):
  self.assertFalse(_dataset_exists(dataset_ref))
 
  def test_delete_dataset_delete_contents_true(self):
- dataset_id = _make_dataset_id("delete_table_true")
+ dataset_id = _make_dataset_id("delete_table_true_with_content")
  project = Config.CLIENT.project
  dataset_ref = bigquery.DatasetReference(project, dataset_id)
  dataset = retry_403(Config.CLIENT.create_dataset)(Dataset(dataset_ref))