dynamic_main: Fix array size check, write test case

t/dynamic_main.bash

@@ -1,10 +1,15 @@
 #!/usr/bin/env bash
 
-fns=( hello )
+fns=( hello hi )
 
 hello() {
 	[ "$1" == help ] && echo -n "Say \"hello.\"" && return 0
 	echo hello.
 }
 
+hi() {
+	[ "$1" == help ] && echo -n "Say \"hi.\"" && return 0
+	echo hi.
+}
+
 . "$(dirname "$0")/../dynamic_main.bash"