platform_tools/android/bin/adb_wait_for_device

#!/bin/bash
#
# Wait for the device to be ready to run tests.

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
source $SCRIPT_DIR/android_setup.sh
source $SCRIPT_DIR/utils/setup_adb.sh

function get_battery_level {
  STATS="$($ADB $DEVICE_SERIAL shell dumpsys batteryproperties)"
  SPLIT=( $STATS )
  for i in "${!SPLIT[@]}"; do
    if [ "${SPLIT[$i]}" = "level:" ]; then
      echo "${SPLIT[$i+1]}"
      return
    fi
  done
  echo "Could not determine battery level!" 1>&2
  echo "0"
}

set -e

# Wait for the device to be connected and fully booted.
while [ "$($ADB $DEVICE_SERIAL shell getprop sys.boot_completed | tr -d '\r')" != "1" ]; do
  echo "Waiting for the device to be connected and ready."
  sleep 5
done

# Wait for battery charge.
DESIRED_BATTERY_LEVEL=30
CURRENT_BATTERY_LEVEL="$(get_battery_level)"
while [ "${CURRENT_BATTERY_LEVEL}" -lt "${DESIRED_BATTERY_LEVEL}" ]; do
  echo "Battery level is ${CURRENT_BATTERY_LEVEL}; waiting to charge to ${DESIRED_BATTERY_LEVEL}"
  sleep 5
  CURRENT_BATTERY_LEVEL="$(get_battery_level)"
done

echo "Ready!"