_yaml: Introduce 'get_sequence()' and 'sequence_at()'/'mapping_at()'

- Adding 'get_sequence' on MappingNode to access sequences in a mapping
- Adding 'sequence_at' on SequenceNode to access sequences in a sequence
- Adding 'mapping_at' on SequenceNode to access mappings in a sequence

Using "*_at" in sequences allows us to quickly understand if we are
dealing with a sequence or a mapping.

1 files changed, 5 insertions, 5 deletions

diff --git a/tests/format/options.py b/tests/format/options.py
index e902b8b86..9c0e043f9 100644
--- a/tests/format/options.py
+++ b/tests/format/options.py
@@ -223,8 +223,8 @@ def test_deep_nesting_level1(cli, datafiles, option, expected):
         'element.bst'])
     result.assert_success()
     loaded = _yaml.load_data(result.output)
-    shallow_list = _yaml.node_get(loaded, list, 'shallow-nest')
-    first_dict = shallow_list[0]
+    shallow_list = loaded.get_sequence('shallow-nest')
+    first_dict = shallow_list.mapping_at(0)
 
     assert first_dict.get_str('animal') == expected
 
@@ -244,8 +244,8 @@ def test_deep_nesting_level2(cli, datafiles, option, expected):
         'element-deeper.bst'])
     result.assert_success()
     loaded = _yaml.load_data(result.output)
-    shallow_list = _yaml.node_get(loaded, list, 'deep-nest')
-    deeper_list = shallow_list[0]
-    first_dict = deeper_list[0]
+    shallow_list = loaded.get_sequence('deep-nest')
+    deeper_list = shallow_list.sequence_at(0)
+    first_dict = deeper_list.mapping_at(0)
 
     assert first_dict.get_str('animal') == expected