C++ components unit test framework (#9284)

Co-authored-by: J. Nick Koston <nick@home-assistant.io>
Co-authored-by: J. Nick Koston <nick@koston.org>

tests/components/main.cpp

@@ -0,0 +1,26 @@
+#include <gtest/gtest.h>
+
+/*
+This special main.cpp replaces the default one.
+It will run all the Google Tests found in all compiled cpp files and then exit with the result
+See README.md for more information
+*/
+
+// Auto generated code by esphome
+// ========== AUTO GENERATED INCLUDE BLOCK BEGIN ===========
+// ========== AUTO GENERATED INCLUDE BLOCK END ==========="
+
+void original_setup() {
+  // This function won't be run.
+
+  // ========== AUTO GENERATED CODE BEGIN ===========
+  // =========== AUTO GENERATED CODE END ============
+}
+
+void setup() {
+  ::testing::InitGoogleTest();
+  int exit_code = RUN_ALL_TESTS();
+  exit(exit_code);
+}
+
+void loop() {}