add back cache tests

Author: geetu040

tests/test_runs/test_run_functions.py

@@ -1659,6 +1659,16 @@ def test_run_on_dataset_with_missing_labels_array(self):
             # repeat, fold, row_id, 6 confidences, prediction and correct label
             assert len(row) == 12
 
+    @pytest.mark.test_server()
+    def test_get_cached_run(self):
+        openml.config.set_root_cache_directory(self.static_cache_dir)
+        openml.runs.functions._get_cached_run(1)
+
+    def test_get_uncached_run(self):
+        openml.config.set_root_cache_directory(self.static_cache_dir)
+        with pytest.raises(openml.exceptions.OpenMLCacheException):
+            openml.runs.functions._get_cached_run(10)
+
     @pytest.mark.sklearn()
     @pytest.mark.test_server()
     def test_run_flow_on_task_downloaded_flow(self):