fix: get_staging_dirs default_version should be optional (#1045)

synthtool/transforms.py

@@ -14,7 +14,7 @@
 
 from pathlib import Path
 import shutil
-from typing import Callable, Iterable, Union, List
+from typing import Callable, Iterable, Union, List, Optional
 import os
 import re
 import sys
@@ -277,13 +277,13 @@ def replace(
     return count_replaced
 
 
-def get_staging_dirs(default_version: str) -> List[Path]:
+def get_staging_dirs(default_version: Optional[str] = None) -> List[Path]:
     """Returns the list of directories, one per version, copied from
     https://github.com/googleapis/googleapis-gen.
 
     Args:
       default_version: the default version of the API. The directory for this version
-        will be the last item in the returned list.
+        will be the last item in the returned list if specified.
 
     Returns: the empty list if no file were copied.
     """
@@ -293,7 +293,9 @@ def get_staging_dirs(default_version: str) -> List[Path]:
         # Collect the subdirectories of the staging directory.
         versions = [v.name for v in staging.iterdir() if v.is_dir()]
         # Reorder the versions so the default version always comes last.
-        versions = [v for v in versions if v != default_version] + [default_version]
+        versions = [v for v in versions if v != default_version]
+        if default_version is not None:
+            versions += [default_version]
         dirs = [staging / v for v in versions]
         for dir in dirs:
             _tracked_paths.add(dir)

tests/test_transforms.py

@@ -268,3 +268,17 @@ def test_copy_with_merge_file_permissions(expand_path_fixtures):
 
     # ensure that the destination existing file now has the correct file permissions
     assert os.stat(destination_file).st_mode == os.stat(template).st_mode
+
+
+@pytest.fixture(scope="function")
+def change_test_dir():
+    cur = os.curdir
+    os.chdir(Path(__file__).parent / "fixtures/staging_dirs")
+    yield
+    os.chdir(cur)
+
+
+def test_get_staging_dirs(change_test_dir):
+    assert [path.name for path in transforms.get_staging_dirs("v1")] == ["v2", "v1"]
+    assert [path.name for path in transforms.get_staging_dirs("v2")] == ["v1", "v2"]
+    assert [path.name for path in transforms.get_staging_dirs()] == ["v1", "v2"]