Fix the "PR-to-Update-Go" GitHub Action

.github/actions/pr-to-update-go/README.rst

@@ -72,3 +72,9 @@ To run the unit tests:
 .. code-block:: shell
 
 	python3 -m unittest discover ./tests
+
+To run the doctests:
+
+.. code-block:: shell
+
+	python3 ./pr_to_update_go/go_pr_maker.py

.github/actions/pr-to-update-go/pr_to_update_go/__main__.py

@@ -10,6 +10,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""
+A utility for automatically updating Go. For full usage information, refer to
+the action's README.rst file.
+
+Options
+	--update-version-only   Exit after updating GO_VERSION file.
+"""
 import os
 import sys
 from argparse import ArgumentParser, Namespace
@@ -21,17 +28,23 @@
 
 
 def main() -> None:
+	"""
+	The entrypoint for running the PR-maker.
+	"""
 	parser = ArgumentParser()
-	parser.add_argument('--update-version-only', type=bool, default=False, help='Exit after updating the GO_VERSION file')
+	parser.add_argument(
+		'--update-version-only',
+		action="store_true",
+		help='Exit after updating the GO_VERSION file'
+	)
 	args: Namespace = parser.parse_args()
 
 	try:
-		github_token: str = os.environ[ENV_GITHUB_TOKEN]
+		github_token = os.environ[ENV_GITHUB_TOKEN]
 	except KeyError:
 		print(f'Environment variable {ENV_GITHUB_TOKEN} must be defined.')
 		sys.exit(1)
-	gh = Github(login_or_token=github_token)
-	GoPRMaker(gh).run(args.update_version_only)
-
+	gh_api = Github(login_or_token=github_token)
+	GoPRMaker(gh_api).run(args.update_version_only)
 
 main()

.github/actions/pr-to-update-go/pr_to_update_go/constants.py

@@ -10,14 +10,88 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""
+The constants module holds some constants used by the PR maker.
+
+Environment variable names, and the meanings of the values of those variables:
+
+	ENV_GIT_AUTHOR_NAME         - The username of the author for commits
+	ENV_GITHUB_REPOSITORY       - The "name" of the repository set by GHA (e.g. octocat/Hello-World)
+	ENV_GITHUB_REPOSITORY_OWNER - The repository owner's name set by GHA (e.g. octocat)
+	ENV_GITHUB_TOKEN            - The token used to access the GitHub API - set by GHA
+	ENV_GO_VERSION_FILE         - The repository-relative path to the file containing the Go version
+	ENV_ENV_FILE                - The repository-relative path to an environment file containing
+	                              a line setting the variable GO_VERSION to the Go version
+	                              (e.g. GO_VERSION=3.2.1)
+
+Miscellaneous:
+
+	GIT_AUTHOR_EMAIL_TEMPLATE - Template used to construct the Git Author's email address.
+	GO_REPO_NAME              - The name of the official Go repository.
+	GO_VERSION_URL            - A URL from which information about Go releases is fetched.
+	RELEASE_PAGE_URL          - The URL of a webpage containing changelog notes about Go releases.
+"""
 from typing import Final
 
 ENV_GIT_AUTHOR_NAME: Final = 'GIT_AUTHOR_NAME'
+"""
+The name of the environment variable set to username of the author for commits.
+"""
+
 ENV_GITHUB_REPOSITORY: Final = 'GITHUB_REPOSITORY'
+"""
+The name of the environment variable set to "name" of the repository set by GHA
+(e.g. octocat/Hello-World).
+"""
+
 ENV_GITHUB_REPOSITORY_OWNER: Final = 'GITHUB_REPOSITORY_OWNER'
+"""
+The name of the environment variable set to repository owner's name set by GHA
+(e.g. octocat).
+"""
+
 ENV_GITHUB_TOKEN: Final = 'GITHUB_TOKEN'
+"""
+The name of the environment variable set to token used to access the GitHub
+API - set by GHA.
+"""
+
 ENV_GO_VERSION_FILE: Final = 'GO_VERSION_FILE'
+"""
+The name of the environment variable set to repository-relative path to the file
+containing the Go version.
+"""
+
+ENV_ENV_FILE: Final = 'ENV_FILE'
+"""
+The name of the environment variable set to repository-relative path to an
+environment file containing a line setting the variable GO_VERSION to the Go
+version (e.g. GO_VERSION=3.2.1).
+"""
+
+
 GIT_AUTHOR_EMAIL_TEMPLATE: Final = '{git_author_name}@users.noreply.github.com'
+"""Template used to construct the Git Author's email address."""
+
 GO_REPO_NAME: Final = 'golang/go'
+"""The name of the official Go repository."""
+
 GO_VERSION_URL: Final = 'https://golang.org/dl/?mode=json'
+"""A URL from which information about Go releases is fetched."""
+
 RELEASE_PAGE_URL: Final = 'https://golang.org/doc/devel/release.html'
+"""The URL of a webpage containing changelog notes about Go releases."""
+
+
+__all__ = [
+	"ENV_GIT_AUTHOR_NAME",
+	"ENV_GITHUB_REPOSITORY",
+	"ENV_GITHUB_REPOSITORY_OWNER",
+	"ENV_GITHUB_TOKEN",
+	"ENV_GO_VERSION_FILE",
+	"ENV_ENV_FILE",
+	"GIT_AUTHOR_EMAIL_TEMPLATE",
+	"GO_REPO_NAME",
+	"GO_VERSION_URL",
+	"RELEASE_PAGE_URL",
+]