Useful when binary is called indirectly (e.g. from emacs).
---
 test/test-lib.sh |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/test/test-lib.sh b/test/test-lib.sh
index cf1b4f0..5a99216 100755
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -533,46 +533,60 @@ test_set_prereq () {
 	satisfied="$satisfied$1 "
 }
 satisfied=" "
 
 test_have_prereq () {
 	case $satisfied in
 	*" $1 "*)
 		: yes, have it ;;
 	*)
 		! : nope ;;
 	esac
 }
 
 # declare prerequisite for the given external binary
 test_declare_external_prereq () {
 	binary="$1"
 	test "$#" = 2 && name=$2 || name="$binary(1)"
 
 	hash $binary 2>/dev/null || eval "
 $binary () {
+	test_missing_external_prereq_${binary}_=t
 	echo -n \"\$test_subtest_missing_external_prereqs_\" | grep -e \" $name \" ||
 	test_subtest_missing_external_prereqs_=\"$test_subtest_missing_external_prereqs_ $name\"
 	false
 }"
 }
 
+# Explicitly require external prerequisite.  Useful when binary is
+# called indirectly (e.g. from emacs).
+# Returns success if dependency is available, failure otherwise.
+test_require_external_prereq () {
+	binary="$1"
+	if [ "$(eval echo -n \$test_missing_external_prereq_${binary}_)" = t ]; then
+		# dependency is missing, call the replacement function to note it
+		eval "$binary"
+	else
+		true
+	fi
+}
+
 # You are not expected to call test_ok_ and test_failure_ directly, use
 # the text_expect_* functions instead.
 
 test_ok_ () {
 	if test "$test_subtest_known_broken_" = "t"; then
 		test_known_broken_ok_ "$@"
 		return
 	fi
 	test_success=$(($test_success + 1))
 	say_color pass "%-6s" "PASS"
 	echo " $@"
 }
 
 test_failure_ () {
 	if test "$test_subtest_known_broken_" = "t"; then
 		test_known_broken_failure_ "$@"
 		return
 	fi
 	test_failure=$(($test_failure + 1))
 	test_failure_message_ "FAIL" "$@"
-- 
1.7.7.2