diff --git a/t/lib-subtest.sh b/t/lib-subtest.sh
new file mode 100644
index 00000000000..3cfe09911a2
--- /dev/null
+++ b/t/lib-subtest.sh
@@ -0,0 +1,86 @@
+_run_sub_test_lib_test_common () {
+	neg="$1" name="$2" descr="$3" # stdin is the body of the test code
+	shift 3
+
+	# intercept pseudo-options at the front of the argument list that we
+	# will not pass to child script
+	skip=
+	while test $# -gt 0
+	do
+		case "$1" in
+		--skip=*)
+			skip=${1#--*=}
+			shift
+			;;
+		*)
+			break
+			;;
+		esac
+	done
+
+	mkdir "$name" &&
+	(
+		# Pretend we're not running under a test harness, whether we
+		# are or not. The test-lib output depends on the setting of
+		# this variable, so we need a stable setting under which to run
+		# the sub-test.
+		sane_unset HARNESS_ACTIVE &&
+		cd "$name" &&
+		write_script "$name.sh" "$TEST_SHELL_PATH" <<-EOF &&
+		test_description='$descr (run in sub test-lib)
+
+		This is run in a sub test-lib so that we do not get incorrect
+		passing metrics
+		'
+
+		# Point to the t/test-lib.sh, which isn't in ../ as usual
+		. "\$TEST_DIRECTORY"/test-lib.sh
+		EOF
+		cat >>"$name.sh" &&
+		export TEST_DIRECTORY &&
+		# The child test re-sources GIT-BUILD-OPTIONS and may thus
+		# override the test output directory. We thus pass it as an
+		# explicit override to the child.
+		TEST_OUTPUT_DIRECTORY_OVERRIDE=$(pwd) &&
+		export TEST_OUTPUT_DIRECTORY_OVERRIDE &&
+		GIT_SKIP_TESTS=$skip &&
+		export GIT_SKIP_TESTS &&
+		sane_unset GIT_TEST_FAIL_PREREQS &&
+		if test -z "$neg"
+		then
+			./"$name.sh" "$@" >out 2>err
+		else
+			! ./"$name.sh" "$@" >out 2>err
+		fi
+	)
+}
+
+run_sub_test_lib_test () {
+	_run_sub_test_lib_test_common '' "$@"
+}
+
+run_sub_test_lib_test_err () {
+	_run_sub_test_lib_test_common '!' "$@"
+}
+
+check_sub_test_lib_test () {
+	name="$1" # stdin is the expected output from the test
+	(
+		cd "$name" &&
+		test_must_be_empty err &&
+		sed -e 's/^> //' -e 's/Z$//' >expect &&
+		test_cmp expect out
+	)
+}
+
+check_sub_test_lib_test_err () {
+	name="$1" # stdin is the expected output from the test
+	# expected error output is in descriptor 3
+	(
+		cd "$name" &&
+		sed -e 's/^> //' -e 's/Z$//' >expect.out &&
+		test_cmp expect.out out &&
+		sed -e 's/^> //' -e 's/Z$//' <&3 >expect.err &&
+		test_cmp expect.err err
+	)
+}
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index cb87768513c..a3865dd77ba 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -19,6 +19,7 @@ modification *should* take notice and update the test vectors here.
 '
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-subtest.sh
 
 try_local_xy () {
 	local x="local" y="alsolocal" &&
@@ -66,93 +67,6 @@ test_expect_success 'success is reported like this' '
 	:
 '
 
-_run_sub_test_lib_test_common () {
-	neg="$1" name="$2" descr="$3" # stdin is the body of the test code
-	shift 3
-
-	# intercept pseudo-options at the front of the argument list that we
-	# will not pass to child script
-	skip=
-	while test $# -gt 0
-	do
-		case "$1" in
-		--skip=*)
-			skip=${1#--*=}
-			shift
-			;;
-		*)
-			break
-			;;
-		esac
-	done
-
-	mkdir "$name" &&
-	(
-		# Pretend we're not running under a test harness, whether we
-		# are or not. The test-lib output depends on the setting of
-		# this variable, so we need a stable setting under which to run
-		# the sub-test.
-		sane_unset HARNESS_ACTIVE &&
-		cd "$name" &&
-		write_script "$name.sh" "$TEST_SHELL_PATH" <<-EOF &&
-		test_description='$descr (run in sub test-lib)
-
-		This is run in a sub test-lib so that we do not get incorrect
-		passing metrics
-		'
-
-		# Point to the t/test-lib.sh, which isn't in ../ as usual
-		. "\$TEST_DIRECTORY"/test-lib.sh
-		EOF
-		cat >>"$name.sh" &&
-		export TEST_DIRECTORY &&
-		# The child test re-sources GIT-BUILD-OPTIONS and may thus
-		# override the test output directory. We thus pass it as an
-		# explicit override to the child.
-		TEST_OUTPUT_DIRECTORY_OVERRIDE=$(pwd) &&
-		export TEST_OUTPUT_DIRECTORY_OVERRIDE &&
-		GIT_SKIP_TESTS=$skip &&
-		export GIT_SKIP_TESTS &&
-		sane_unset GIT_TEST_FAIL_PREREQS &&
-		if test -z "$neg"
-		then
-			./"$name.sh" "$@" >out 2>err
-		else
-			! ./"$name.sh" "$@" >out 2>err
-		fi
-	)
-}
-
-run_sub_test_lib_test () {
-	_run_sub_test_lib_test_common '' "$@"
-}
-
-run_sub_test_lib_test_err () {
-	_run_sub_test_lib_test_common '!' "$@"
-}
-
-check_sub_test_lib_test () {
-	name="$1" # stdin is the expected output from the test
-	(
-		cd "$name" &&
-		test_must_be_empty err &&
-		sed -e 's/^> //' -e 's/Z$//' >expect &&
-		test_cmp expect out
-	)
-}
-
-check_sub_test_lib_test_err () {
-	name="$1" # stdin is the expected output from the test
-	# expected error output is in descriptor 3
-	(
-		cd "$name" &&
-		sed -e 's/^> //' -e 's/Z$//' >expect.out &&
-		test_cmp expect.out out &&
-		sed -e 's/^> //' -e 's/Z$//' <&3 >expect.err &&
-		test_cmp expect.err err
-	)
-}
-
 test_expect_success 'pretend we have a fully passing test suite' '
 	run_sub_test_lib_test full-pass "3 passing tests" <<-\EOF &&
 	for i in 1 2 3
