Fix clang-tidy triggering full scan on Python-only core file changes (#9412)

script/helpers.py

@@ -168,21 +168,26 @@ def get_changed_components() -> list[str] | None:
     """Get list of changed components using list-components.py script.
 
     This function:
-    1. First checks if any core files (esphome/core/*) changed - if so, returns None
+    1. First checks if any core C++/header files (esphome/core/*.{cpp,h,hpp,cc,cxx,c}) changed - if so, returns None
     2. Otherwise delegates to ./script/list-components.py --changed which:
        - Analyzes all changed files
        - Determines which components are affected (including dependencies)
        - Returns a list of component names that need to be checked
 
     Returns:
-        - None: Core files changed, need full scan
+        - None: Core C++/header files changed, need full scan
         - Empty list: No components changed (only non-component files changed)
         - List of strings: Names of components that need checking (e.g., ["wifi", "mqtt"])
     """
-    # Check if any core files changed first
+    # Check if any core C++ or header files changed first
     changed = changed_files()
-    if any(f.startswith("esphome/core/") for f in changed):
-        print("Core files changed - will run full clang-tidy scan")
+    core_cpp_changed = any(
+        f.startswith("esphome/core/")
+        and f.endswith((".cpp", ".h", ".hpp", ".cc", ".cxx", ".c"))
+        for f in changed
+    )
+    if core_cpp_changed:
+        print("Core C++/header files changed - will run full clang-tidy scan")
         return None
 
     # Use list-components.py to get changed components
@@ -207,10 +212,10 @@ def _filter_changed_ci(files: list[str]) -> list[str]:
     This function implements intelligent filtering to reduce CI runtime by only
     checking files that could be affected by the changes. It handles three scenarios:
 
-    1. Core files changed (returns None from get_changed_components):
-       - Triggered when any file in esphome/core/ is modified
+    1. Core C++/header files changed (returns None from get_changed_components):
+       - Triggered when any C++/header file in esphome/core/ is modified
        - Action: Check ALL files (full scan)
-       - Reason: Core files are used throughout the codebase
+       - Reason: Core C++/header files are used throughout the codebase
 
     2. No components changed (returns empty list from get_changed_components):
        - Triggered when only non-component files changed (e.g., scripts, configs)

tests/script/test_helpers.py

@@ -394,10 +394,10 @@ def test_get_changed_files_from_command_relative_paths() -> None:
         ["esphome/core/application.h", "esphome/core/defines.h"],
     ],
 )
-def test_get_changed_components_core_files_trigger_full_scan(
+def test_get_changed_components_core_cpp_files_trigger_full_scan(
     changed_files_list: list[str],
 ) -> None:
-    """Test that core file changes trigger full scan without calling subprocess."""
+    """Test that core C++/header file changes trigger full scan without calling subprocess."""
     with patch("helpers.changed_files") as mock_changed:
         mock_changed.return_value = changed_files_list
 
@@ -406,6 +406,43 @@ def test_get_changed_components_core_files_trigger_full_scan(
         assert result is None
 
 
+def test_get_changed_components_core_python_files_no_full_scan() -> None:
+    """Test that core Python file changes do NOT trigger full scan."""
+    changed_files_list = [
+        "esphome/core/__init__.py",
+        "esphome/core/config.py",
+        "esphome/components/wifi/wifi.cpp",
+    ]
+
+    with patch("helpers.changed_files") as mock_changed:
+        mock_changed.return_value = changed_files_list
+
+        mock_result = Mock()
+        mock_result.stdout = "wifi\n"
+
+        with patch("subprocess.run", return_value=mock_result):
+            result = get_changed_components()
+            # Should NOT return None - should call list-components.py
+            assert result == ["wifi"]
+
+
+def test_get_changed_components_mixed_core_files_with_cpp() -> None:
+    """Test that mixed Python and C++ core files still trigger full scan due to C++ file."""
+    changed_files_list = [
+        "esphome/core/__init__.py",
+        "esphome/core/config.py",
+        "esphome/core/helpers.cpp",  # This C++ file should trigger full scan
+        "esphome/components/wifi/wifi.cpp",
+    ]
+
+    with patch("helpers.changed_files") as mock_changed:
+        mock_changed.return_value = changed_files_list
+
+        # Should return None without calling subprocess due to helpers.cpp
+        result = get_changed_components()
+        assert result is None
+
+
 @pytest.mark.parametrize(
     ("changed_files_list", "expected"),
     [
@@ -451,7 +488,7 @@ def test_get_changed_components_script_failure() -> None:
 @pytest.mark.parametrize(
     ("components", "all_files", "expected_files"),
     [
-        # Core files changed (full scan)
+        # Core C++/header files changed (full scan)
         (
             None,
             ["esphome/components/wifi/wifi.cpp", "esphome/core/helpers.cpp"],
@@ -591,7 +628,7 @@ def test_filter_changed_empty_file_handling(
 
 
 def test_filter_changed_ci_full_scan() -> None:
-    """Test _filter_changed_ci when core files changed (full scan)."""
+    """Test _filter_changed_ci when core C++/header files changed (full scan)."""
     all_files = ["esphome/components/wifi/wifi.cpp", "esphome/core/helpers.cpp"]
 
     with patch("helpers.get_changed_components", return_value=None):