build system: add the initial set of pytest-based build system tests

tools/test_build_system/test_build_system_helpers/editing.py

@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: Apache-2.0
+import typing
+from pathlib import Path
+
+
+def append_to_file(filename: typing.Union[str, Path], what: str) -> None:
+    with open(filename, 'a', encoding='utf-8') as f:
+        f.write(what)
+
+
+def replace_in_file(filename: typing.Union[str, Path], search: str, replace: str) -> None:
+    with open(filename, 'r', encoding='utf-8') as f:
+        data = f.read()
+    result = data.replace(search, replace)
+    with open(filename, 'w', encoding='utf-8') as f:
+        f.write(result)