Fix zsh glob error

Zsh by default will error if a glob matches nothing (a smart default).
We need it to not error, and even better, to not use the Bash default of
using the pattern. Set nullglob to expand it to nothing.

Don't set the Bash version of nullglob in liquidprompt, since Bash
doesn't do local options well, and not at all until version 4.4. It is
safe to expand to a single string with the "*" in it, since the first
check we do is for the file existing, which it will not.

Add the sysfs power supply interface to the external-tool-tester.sh.

liquidprompt

@@ -2342,6 +2342,10 @@ _lp_wifi() {
 case "$LP_OS" in
     Linux)
     __lp_battery_sysfs() {
+        if (( _LP_SHELL_zsh )); then
+            setopt local_options nullglob
+        fi
+
         local power_supply
         for power_supply in "${_LP_LINUX_POWERSUPPLY_PATH}/"*; do
             if ! [[ -r "${power_supply}/type" && -r "${power_supply}/present" && \

tools/external-tool-tester.sh

@@ -3,6 +3,13 @@
 # Do NOT error on failed commands
 set +e
 
+# Don't error (or do anything) for no matching globs.
+if [ -n "${ZSH_VERSION-}" ]; then
+  setopt nullglob
+else  # Bash
+  shopt -s nullglob
+fi
+
 # Error if the output is a terminal
 if [ -t 1 ]; then
   printf 'This script must be redirected to a file, or special characters will be lost
@@ -64,6 +71,11 @@ test_tool logname
 test_tool screen -ls
 test_tool tmux list-sessions
 
+for power_supply in "/sys/class/power_supply/"*; do
+  for interface in "${power_supply}/"*; do
+    test_tool cat "$interface"
+  done
+done
 test_tool acpi --battery
 test_tool pmset -g batt