Refactor mapping read-helper boundary to shared extras

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

tests/test_mapping_read_helper_import_boundary.py

@@ -3,14 +3,12 @@
 
 import pytest
 
+from tests.test_mapping_utils_import_boundary import EXPECTED_MAPPING_EXTRA_IMPORTERS
 from tests.test_mapping_reader_usage import MAPPING_READER_TARGET_FILES
 
 pytestmark = pytest.mark.architecture
 
 
-EXPECTED_READ_HELPER_EXTRA_IMPORTERS = ("tests/test_mapping_utils.py",)
-
-
 def _imports_read_string_key_mapping(module_text: str) -> bool:
     module_ast = ast.parse(module_text)
     for node in module_ast.body:
@@ -40,6 +38,6 @@ def test_read_string_key_mapping_imports_are_centralized():
         path.as_posix() for path in MAPPING_READER_TARGET_FILES
     )
     expected_modules = sorted(
-        [*expected_runtime_modules, *EXPECTED_READ_HELPER_EXTRA_IMPORTERS]
+        [*expected_runtime_modules, *EXPECTED_MAPPING_EXTRA_IMPORTERS]
     )
     assert discovered_modules == expected_modules