test: add function to explicitly check for external dependencies

Useful when binary is called indirectly (e.g. from emacs).

diff --git a/test/test-lib.sh b/test/test-lib.sh
index fe80e89314e201feea3199a2a7c7b443b3b7d2fc..2422e32d9ece07aae03871fb0c81ea7b2825608c 100644 (file)
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -555,12 +555,26 @@ test_declare_external_prereq () {
 
        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.