Coverage for little_loops / loops / yaml_state_editor.py: 100%

1"""Round-trip YAML editor for loop state action blocks. 

2 

3Uses ruamel.yaml (round-trip mode) to preserve `action: |` block scalar 

4formatting when extracting or replacing a named state's action field. 

5""" 

6 

7from __future__ import annotations 

8 

9from io import StringIO 

10from pathlib import Path 

11 

12from ruamel.yaml import YAML 

13from ruamel.yaml.scalarstring import LiteralScalarString 

14 

15from little_loops.file_utils import atomic_write 

16 

17 

18def extract_action(loop_yaml_path: Path, state_name: str) -> str: 

19 """Return the action string for *state_name* in the loop YAML at *loop_yaml_path*. 

20 

21 Raises KeyError if *state_name* is not found in ``states``. 

22 """ 

23 yaml = YAML(typ="rt") 

24 data = yaml.load(loop_yaml_path) 

25 return str(data["states"][state_name]["action"]) 

26 

27 

28def replace_action(loop_yaml_path: Path, state_name: str, new_action: str) -> None: 

29 """Replace the action for *state_name* in the loop YAML at *loop_yaml_path*. 

30 

31 Writes back in-place using atomic_write, preserving block scalar style 

32 (``action: |``) for the modified state and leaving all other states and 

33 keys unchanged. 

34 

35 Raises KeyError if *state_name* is not found in ``states``. 

36 """ 

37 yaml = YAML(typ="rt") 

38 data = yaml.load(loop_yaml_path) 

39 # LiteralScalarString forces ruamel to emit `action: |` rather than 

40 # choosing a quoted or flow scalar style for the new value. 

41 data["states"][state_name]["action"] = LiteralScalarString(new_action) 

42 buf = StringIO() 

43 yaml.dump(data, buf) 

44 atomic_write(loop_yaml_path, buf.getvalue())