[PATCH v2] test-lib: allow short options to be bundled

[Matheus Tavares <matheus.bernardino@usp.br>]

When debugging a test (or a set of tests), it's common to execute it
with some combination of short options, such as:

	$ ./txxx-testname.sh -d -x -i

In cases like this, CLIs usually allow the short options to be bundled
in a single argument, for convenience and agility. Let's add this
feature to test-lib, allowing the above command to be run as:

	$ ./txxx-testname.sh -dxi
	(or any other permutation, e.g. '-ixd')

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---

Changes since v1:
- Added a check for bundles containing more than one "option that
  requires args" (e.g. '-rr'), in which case we error-out. We could
  interpret '-rr 1 2' as 'run tests 1 _and_ 2', but the unbundled
  format, '-r 1 -r 2', is not currently interpreted like that (the last
  just overrides the previous). So, for simplicity, let's only forbid
  such bundles for now.
- Used "$1" instead of "$@" to get the argument in parse_option()
- Replaced occurrences of "stacked options" to "bundled options"
- Eliminated spawning of extra processes in the bundled options parser
- s/below/later/ in the parser loop comment, to make it clearer

 t/README      |  3 ++-
 t/test-lib.sh | 62 +++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/t/README b/t/README
index 9afd61e3ca..080bc59fc4 100644
--- a/t/README
+++ b/t/README
@@ -69,7 +69,8 @@ You can also run each test individually from command line, like this:
 
 You can pass --verbose (or -v), --debug (or -d), and --immediate
 (or -i) command line argument to the test, or by setting GIT_TEST_OPTS
-appropriately before running "make".
+appropriately before running "make". Short options can be bundled, i.e.
+'-d -v' is the same as '-dv'.
 
 -v::
 --verbose::
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 0ea1e5a05e..dda770ec94 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -78,20 +78,24 @@ then
 	exit 1
 fi
 
-# Parse options while taking care to leave $@ intact, so we will still
-# have all the original command line options when executing the test
-# script again for '--tee' and '--verbose-log' below.
 store_arg_to=
-prev_opt=
-for opt
-do
-	if test -n "$store_arg_to"
+opt_required_arg=
+# $1: option string
+# $2: name of the var where the arg will be stored
+mark_option_requires_arg ()
+{
+	if test -n "$opt_required_arg"
 	then
-		eval $store_arg_to=\$opt
-		store_arg_to=
-		prev_opt=
-		continue
+		echo "error: options that require args cannot be bundled" \
+			"together: '$opt_required_arg' and '$1'" >&2
+		exit 1
 	fi
+	opt_required_arg=$1
+	store_arg_to=$2
+}
+
+parse_option () {
+	local opt="$1"
 
 	case "$opt" in
 	-d|--d|--de|--deb|--debu|--debug)
@@ -101,7 +105,7 @@ do
 	-l|--l|--lo|--lon|--long|--long-|--long-t|--long-te|--long-tes|--long-test|--long-tests)
 		GIT_TEST_LONG=t; export GIT_TEST_LONG ;;
 	-r)
-		store_arg_to=run_list
+		mark_option_requires_arg "$opt" run_list
 		;;
 	--run=*)
 		run_list=${opt#--*=} ;;
@@ -185,12 +189,42 @@ do
 	*)
 		echo "error: unknown test option '$opt'" >&2; exit 1 ;;
 	esac
+}
+
+# Parse options while taking care to leave $@ intact, so we will still
+# have all the original command line options when executing the test
+# script again for '--tee' and '--verbose-log' later.
+for opt
+do
+	if test -n "$store_arg_to"
+	then
+		eval $store_arg_to=\$opt
+		store_arg_to=
+		opt_required_arg=
+		continue
+	fi
 
-	prev_opt=$opt
+	case "$opt" in
+	--*)
+		parse_option "$opt" ;;
+	-?*)
+		# bundled short options must be fed separately to parse_option
+		opt=${opt#-}
+		while test -n "$opt"
+		do
+			extra=${opt#?}
+			this=${opt%$extra}
+			opt=$extra
+			parse_option "-$this"
+		done
+		;;
+	*)
+		echo "error: unknown test option '$opt'" >&2; exit 1 ;;
+	esac
 done
 if test -n "$store_arg_to"
 then
-	echo "error: $prev_opt requires an argument" >&2
+	echo "error: $opt_required_arg requires an argument" >&2
 	exit 1
 fi
 
-- 
2.25.1