Convert pmset-simulator to tests

The pmset-simulator function was actually quite helpful, but without a
testing framework around it, there was no automated testing done. Which
meant my mistake a while back was not caught.

Convert those inputs into a real testing function, so that we can test
the data function against real test cases.

tests/test_pmset.sh

@@ -0,0 +1,79 @@
+
+# Load MacOS version of _lp_battery()
+uname() { printf 'Darwin'; }
+
+. ../liquidprompt --no-activate
+unset -f uname
+
+LP_ENABLE_BATT=1
+
+typeset -a outputs statuses values
+
+# Simulated, originally from ./pmset-simulator
+# https://github.com/nojhan/liquidprompt/issues/315
+outputs+=(
+"Now drawing from 'AC Power'"
+)
+statuses+=(4)
+values+=('')
+# https://github.com/nojhan/liquidprompt/issues/326#issuecomment-66120495
+outputs+=(
+"Now drawing from 'AC Power'
+ -InternalBattery-0 37%; AC attached; not charging"
+)
+statuses+=(2)
+values+=(37)
+# https://github.com/nojhan/liquidprompt/issues/326
+outputs+=(
+"Now drawing from 'AC Power'
+ -InternalBattery-0 8%; charging; 2:46 remaining"
+)
+statuses+=(2)
+values+=(8)
+# https://github.com/nojhan/liquidprompt/issues/326
+outputs+=(
+"Now drawing from 'Battery Power'
+ -InternalBattery-0 9%; discharging; (no estimate)"
+)
+statuses+=(0)
+values+=(9)
+# https://github.com/nojhan/liquidprompt/issues/326
+outputs+=(
+"Now drawing from 'Battery Power'
+ -InternalBattery-0 7%; discharging; 0:13 remaining
+    Battery Warning: Early"
+)
+statuses+=(0)
+values+=(7)
+
+
+function test_pmset {
+
+  pmset() {
+    printf '%s\n' "$__output"
+  }
+
+  for (( index=0; index < ${#values[@]}; index++ )); do
+    __output=${outputs[$index]}
+
+    LP_BATTERY_THRESHOLD=100
+    _lp_battery
+    assertEquals "pmset battery below returns" "${statuses[$index]}" "$?"
+    assertEquals "pmset battery value" "${values[$index]}" "$lp_battery"
+
+    _status=${statuses[$index]}
+    (( _status < 4 )) && _status=$(( _status + 1 ))
+
+    LP_BATTERY_THRESHOLD=0
+    _lp_battery
+    assertEquals "pmset battery above returns" "$_status" "$?"
+    assertEquals "pmset battery value" "${values[$index]}" "$lp_battery"
+  done
+}
+
+if [ -n "${ZSH_VERSION-}" ]; then
+  SHUNIT_PARENT="$0"
+  setopt shwordsplit ksh_arrays
+fi
+
+. ./shunit2