added tests to improve coverage

tests/test_aggregate.py

 from common_helper_mongo.aggregate import (
     get_all_value_combinations_of_fields, get_field_average, get_field_sum, get_list_of_all_values,
-    get_objects_and_count_of_occurrence,
+    get_list_of_all_values_and_collect_information_of_additional_field, get_objects_and_count_of_occurrence,
 )
 from tests.base_class_database_test import MongoDbTest
 
@@ -37,7 +37,7 @@ class TestAggregate(MongoDbTest):
 
     def test_get_all_value_combinations_of_fields_id(self):
         self.add_list_test_data()
-        result = get_all_value_combinations_of_fields(self.test_collection, "$test_list", "$_id", unwind=True, match=None)
+        result = get_all_value_combinations_of_fields(self.test_collection, "$test_list", "$_id", unwind=True)
         self.assertIsInstance(result, dict, "result should be a dict")
         self.assertEqual(len(result.keys()), 4, "number of results not correct")
         self.assertEqual(len(result['c']), 2, "c should have two related object ids")
@@ -77,3 +77,13 @@ class TestAggregate(MongoDbTest):
         self.add_simple_test_data()
         result = get_field_sum(self.test_collection, "$test_int", match={"test_int": {"$lt": 5}})
         self.assertEqual(result, 10)
+
+    def test_get_field_execute_operation_empty(self):
+        result = get_field_sum(self.test_collection, "$test_int")
+        self.assertEqual(result, 0)
+
+    def test_get_list_of_all_values_and_collect_information_of_additional_field(self):
+        self.add_list_test_data()
+        with self.assertLogs() as logger:
+            get_list_of_all_values_and_collect_information_of_additional_field(self.test_collection, "$test_list", "$_id", unwind=True)
+            assert 'deprecation warning' in logger.output.pop()