Added test for the "no" energy tool case

plugins/available/battery.plugin.bash

@@ -74,7 +74,11 @@ battery_percentage(){
     COMMAND_OUTPUT="no"
   fi
 
+  if [ "${COMMAND_OUTPUT}" != "no" ]; then
     printf "%02d" "${COMMAND_OUTPUT:--1}"
+  else
+    echo "${COMMAND_OUTPUT}"
+  fi
 }
 
 battery_charge(){

test/plugins/battery.plugin.bats

@@ -34,6 +34,18 @@ function setup_command_exists {
   }
 }
 
+#######################
+#
+# no tool
+#
+
+@test 'plugins battery: battery-percentage with no tool' {
+  setup_command_exists "fooooo"
+
+  run battery_percentage
+  assert_output "no"
+}
+
 #######################
 #
 # pmset