Don't compile unnecessary platform files (e.g. ESP8266 files on ESP32) (#9354)

tests/unit_tests/test_loader.py

@@ -0,0 +1,63 @@
+"""Unit tests for esphome.loader module."""
+
+from unittest.mock import MagicMock, patch
+
+from esphome.loader import ComponentManifest
+
+
+def test_component_manifest_resources_with_filter_source_files() -> None:
+    """Test that ComponentManifest.resources correctly filters out excluded files."""
+    # Create a mock module with FILTER_SOURCE_FILES function
+    mock_module = MagicMock()
+    mock_module.FILTER_SOURCE_FILES = lambda: [
+        "platform_esp32.cpp",
+        "platform_esp8266.cpp",
+    ]
+    mock_module.__package__ = "esphome.components.test_component"
+
+    # Create ComponentManifest instance
+    manifest = ComponentManifest(mock_module)
+
+    # Mock the files in the package
+    def create_mock_file(filename: str) -> MagicMock:
+        mock_file = MagicMock()
+        mock_file.name = filename
+        mock_file.is_file.return_value = True
+        return mock_file
+
+    mock_files = [
+        create_mock_file("test.cpp"),
+        create_mock_file("test.h"),
+        create_mock_file("platform_esp32.cpp"),
+        create_mock_file("platform_esp8266.cpp"),
+        create_mock_file("common.cpp"),
+        create_mock_file("README.md"),  # Should be excluded by extension
+    ]
+
+    # Mock importlib.resources
+    with patch("importlib.resources.files") as mock_files_func:
+        mock_package_files = MagicMock()
+        mock_package_files.iterdir.return_value = mock_files
+        mock_package_files.joinpath = lambda name: MagicMock(is_file=lambda: True)
+        mock_files_func.return_value = mock_package_files
+
+        # Get resources
+        resources = manifest.resources
+
+        # Convert to list of filenames for easier testing
+        resource_names = [r.resource for r in resources]
+
+        # Check that platform files are excluded
+        assert "platform_esp32.cpp" not in resource_names
+        assert "platform_esp8266.cpp" not in resource_names
+
+        # Check that other source files are included
+        assert "test.cpp" in resource_names
+        assert "test.h" in resource_names
+        assert "common.cpp" in resource_names
+
+        # Check that non-source files are excluded
+        assert "README.md" not in resource_names
+
+        # Verify the correct number of resources
+        assert len(resources) == 3  # test.cpp, test.h, common.cpp