Refactor rule loading for testability (#2456)

rules: Introduce tests for YAML rule loading functionality.

lib/logitech_receiver/diversion.py

@@ -1547,23 +1547,29 @@ def _save_config_rule_file(file_name=_file_path):
     return True
 
 
-def _load_config_rule_file():
+def load_config_rule_file():
+    """Loads user configured rules."""
     global rules
-    loaded_rules = []
+
     if _path.isfile(_file_path):
-        try:
-            with open(_file_path) as config_file:
-                loaded_rules = []
-                for loaded_rule in _yaml_safe_load_all(config_file):
-                    rule = Rule(loaded_rule, source=_file_path)
-                    if logger.isEnabledFor(logging.DEBUG):
-                        logger.debug("load rule: %s", rule)
-                    loaded_rules.append(rule)
-                if logger.isEnabledFor(logging.INFO):
-                    logger.info("loaded %d rules from %s", len(loaded_rules), config_file.name)
-        except Exception as e:
-            logger.error("failed to load from %s\n%s", _file_path, e)
-    rules = Rule([Rule(loaded_rules, source=_file_path), built_in_rules])
+        rules = _load_rule_config(_file_path)
 
 
-_load_config_rule_file()
+def _load_rule_config(file_path: str) -> Rule:
+    loaded_rules = []
+    try:
+        with open(file_path) as config_file:
+            loaded_rules = []
+            for loaded_rule in _yaml_safe_load_all(config_file):
+                rule = Rule(loaded_rule, source=file_path)
+                if logger.isEnabledFor(logging.DEBUG):
+                    logger.debug("load rule: %s", rule)
+                loaded_rules.append(rule)
+            if logger.isEnabledFor(logging.INFO):
+                logger.info("loaded %d rules from %s", len(loaded_rules), config_file.name)
+    except Exception as e:
+        logger.error("failed to load from %s\n%s", file_path, e)
+    return Rule([Rule(loaded_rules, source=file_path), built_in_rules])
+
+
+load_config_rule_file()

lib/solaar/ui/diversion_rules.py

@@ -229,7 +229,7 @@ class DiversionDialog:
         self.dirty = False
         for c in self.selected_rule_edit_panel.get_children():
             self.selected_rule_edit_panel.remove(c)
-        _DIV._load_config_rule_file()
+        _DIV.load_config_rule_file()
         self.model = self._create_model()
         self.view.set_model(self.model)
         self.view.expand_all()

tests/logitech_receiver/test_diversion.py

@@ -0,0 +1,57 @@
+import textwrap
+
+from unittest import mock
+from unittest.mock import mock_open
+
+import pytest
+
+from logitech_receiver import diversion
+
+
+@pytest.fixture
+def rule_config():
+    rule_content = """
+    %YAML 1.3
+    ---
+    - MouseGesture: Mouse Left
+    - KeyPress:
+      - [Control_L, Alt_L, Left]
+      - click
+    ...
+    ---
+    - MouseGesture: Mouse Up
+    - KeyPress:
+      - [Super_L, Up]
+      - click
+    ...
+    ---
+    - Test: [thumb_wheel_up, 10]
+    - KeyPress:
+      - [Control_L, Page_Down]
+      - click
+    ...
+    ---
+    """
+    return textwrap.dedent(rule_content)
+
+
+def test_load_rule_config(rule_config):
+    expected_rules = [
+        [
+            diversion.MouseGesture,
+            diversion.KeyPress,
+        ],
+        [diversion.MouseGesture, diversion.KeyPress],
+        [diversion.Test, diversion.KeyPress],
+    ]
+
+    with mock.patch("builtins.open", new=mock_open(read_data=rule_config)):
+        loaded_rules = diversion._load_rule_config(file_path=mock.Mock())
+
+    assert len(loaded_rules.components) == 2  # predefined and user configured rules
+    user_configured_rules = loaded_rules.components[0]
+    assert isinstance(user_configured_rules, diversion.Rule)
+
+    for components, expected_components in zip(user_configured_rules.components, expected_rules):
+        for component, expected_component in zip(components.components, expected_components):
+            assert isinstance(component, expected_component)