tests: move code to run tests under bash into a helper library

The following patch will add tests for the bash prompt functions as a
new test script, which also has to be run under bash.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-bash.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+#
+# Ensures that tests are run under Bash; primarily intended for running tests
+# of the completion script.
+
+if test -n "$BASH" && test -z "$POSIXLY_CORRECT"; then
+	# we are in full-on bash mode
+	true
+elif type bash >/dev/null 2>&1; then
+	# execute in full-on bash mode
+	unset POSIXLY_CORRECT
+	exec bash "$0" "$@"
+else
+	echo '1..0 #SKIP skipping bash completion tests; bash not available'
+	exit 0
+fi
+
+. ./test-lib.sh

t/t9902-completion.sh

@@ -3,21 +3,9 @@
 # Copyright (c) 2012 Felipe Contreras
 #
 
-if test -n "$BASH" && test -z "$POSIXLY_CORRECT"; then
-	# we are in full-on bash mode
-	true
-elif type bash >/dev/null 2>&1; then
-	# execute in full-on bash mode
-	unset POSIXLY_CORRECT
-	exec bash "$0" "$@"
-else
-	echo '1..0 #SKIP skipping bash completion tests; bash not available'
-	exit 0
-fi
-
 test_description='test bash completion'
 
-. ./test-lib.sh
+. ./lib-bash.sh
 
 complete ()
 {