add error handling for invalid input

Author: zhumin8

hermetic_build/library_generation/generate_repo.py

@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import copy
-import re
 import shutil
 from pathlib import Path
 from typing import Optional
@@ -137,6 +136,8 @@ def _get_target_libraries_from_api_path(
         A list of LibraryConfig objects matching the target API path, or an
         empty list if no matches are found.
     """
+    if not ends_with_version(target_api_path):
+        raise ValueError("api_path is not ending with a version is not supported")
     target_libraries = []
     for library in config.libraries:
         target_library = copy.deepcopy(library)

hermetic_build/library_generation/tests/generate_repo_unit_tests.py

@@ -114,6 +114,21 @@ def test_get_target_library_returns_selected_api_path_plus_dep(self):
 
         self.assertEqual([another_library_v1], target_libraries)
 
+    def test_get_target_library_invalid_target_api_path(self):
+        """
+        Tests when the api_path is invalid and sys.exit is called.
+        """
+        config = GenerateRepoTest.__get_an_empty_library_config()
+        with self.assertRaises(ValueError) as context:
+            _target_libraries = get_target_libraries(
+                config, target_api_path="google/cloud/another/library/type"
+            )
+
+        self.assertEqual(
+            str(context.exception),
+            "api_path is not ending with a version is not supported",
+        )
+
     @staticmethod
     def __get_an_empty_generation_config() -> GenerationConfig:
         return GenerationConfig(