patch, 4 partsgit-prompt.sh: add tests for submodule indicator

diff --git a/t/t9903-bash-prompt.sh b/t/t9903-bash-prompt.sh
index 97c9b32..4dce366 100755
--- a/t/t9903-bash-prompt.sh
+++ b/t/t9903-bash-prompt.sh
@@ -37,6 +37,11 @@ test_expect_success 'setup for prompt tests' '
 	git commit -m "yet another b2" file &&
 	mkdir ignored_dir &&
 	echo "ignored_dir/" >>.gitignore &&
+	git checkout -b submodule &&
+	git submodule add ./. sub &&
+	git -C sub checkout master &&
+	git add sub &&
+	git commit -m submodule &&
 	git checkout master
 '
 
@@ -755,4 +760,42 @@ test_expect_success 'prompt - hide if pwd ignored - inside gitdir (stderr)' '
 	test_cmp expected "$actual"
 '
 
+test_expect_success 'prompt - submodule indicator' '
+	printf " (sub:master)" >expected &&
+	git checkout submodule &&
+	test_when_finished "git checkout master" &&
+	(
+		cd sub &&
+		GIT_PS1_SHOWSUBMODULE=1 &&
+		__git_ps1 >"$actual"
+	) &&
+	test_cmp expected "$actual"
+'
+
+test_expect_success 'prompt - submodule indicator - verify false' '
+	printf " (master)" >expected &&
+	git checkout submodule &&
+	test_when_finished "git checkout master" &&
+	(
+		cd sub &&
+		GIT_PS1_SHOWSUBMODULE= &&
+		__git_ps1 >"$actual"
+	) &&
+	test_cmp expected "$actual"
+'
+
+test_expect_success 'prompt - submodule indicator - dirty status indicator' '
+	printf " (+sub:b1)" >expected &&
+	git checkout submodule &&
+	git -C sub checkout b1 &&
+	test_when_finished "git checkout master" &&
+	(
+		cd sub &&
+		GIT_PS1_SHOWSUBMODULE=1 &&
+		__git_ps1 >"$actual"
+	) &&
+	test_cmp expected "$actual"
+'
+
+
 test_done