kunit: add bash completion

Currently, kunit.py has many subcommands and options, making it difficult
to remember them without checking the help message.

Add --list-cmds and --list-opts to kunit.py to get available commands and
options, use those outputs in kunit-completion.sh to show completion.

This implementation is similar to perf and tools/perf/perf-completion.sh.

Example output:
  $ source tools/testing/kunit/kunit-completion.sh
  $ ./tools/testing/kunit/kunit.py [TAB][TAB]
  build   config  exec    parse   run
  $ ./tools/testing/kunit/kunit.py run --k[TAB][TAB]
  --kconfig_add  --kernel_args  --kunitconfig

Link: https://lore.kernel.org/r/20260117-kunit-completion-v2-1-cabd127d0801@gmail.com
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Ryota Sakamoto <sakamo.ryota@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
index e3d82a038f93..4ec5ecba6d49 100755
--- a/tools/testing/kunit/kunit.py
+++ b/tools/testing/kunit/kunit.py
@@ -328,6 +328,17 @@ def get_default_build_dir() -> str:
 		return os.path.join(os.environ['KBUILD_OUTPUT'], '.kunit')
 	return '.kunit'
 
+def add_completion_opts(parser: argparse.ArgumentParser) -> None:
+	parser.add_argument('--list-opts',
+			    help=argparse.SUPPRESS,
+			    action='store_true')
+
+def add_root_opts(parser: argparse.ArgumentParser) -> None:
+	parser.add_argument('--list-cmds',
+			    help=argparse.SUPPRESS,
+			    action='store_true')
+	add_completion_opts(parser)
+
 def add_common_opts(parser: argparse.ArgumentParser) -> None:
 	parser.add_argument('--build_dir',
 			    help='As in the make command, it specifies the build '
@@ -379,6 +390,8 @@ def add_common_opts(parser: argparse.ArgumentParser) -> None:
 			    help='Additional QEMU arguments, e.g. "-smp 8"',
 			    action='append', metavar='')
 
+	add_completion_opts(parser)
+
 def add_build_opts(parser: argparse.ArgumentParser) -> None:
 	parser.add_argument('--jobs',
 			    help='As in the make command, "Specifies  the number of '
@@ -574,6 +587,7 @@ subcommand_handlers_map = {
 def main(argv: Sequence[str]) -> None:
 	parser = argparse.ArgumentParser(
 			description='Helps writing and running KUnit tests.')
+	add_root_opts(parser)
 	subparser = parser.add_subparsers(dest='subcommand')
 
 	# The 'run' command will config, build, exec, and parse in one go.
@@ -608,12 +622,28 @@ def main(argv: Sequence[str]) -> None:
 	parse_parser.add_argument('file',
 				  help='Specifies the file to read results from.',
 				  type=str, nargs='?', metavar='input_file')
+	add_completion_opts(parse_parser)
 
 	cli_args = parser.parse_args(massage_argv(argv))
 
 	if get_kernel_root_path():
 		os.chdir(get_kernel_root_path())
 
+	if cli_args.list_cmds:
+		print(" ".join(subparser.choices.keys()))
+		return
+
+	if cli_args.list_opts:
+		target_parser = subparser.choices.get(cli_args.subcommand)
+		if not target_parser:
+			target_parser = parser
+
+		# Accessing private attribute _option_string_actions to get
+		# the list of options. This is not a public API, but argparse
+		# does not provide a way to inspect options programmatically.
+		print(' '.join(target_parser._option_string_actions.keys()))
+		return
+
 	subcomand_handler = subcommand_handlers_map.get(cli_args.subcommand, None)
 
 	if subcomand_handler is None: