Fastlane capture_android_screenshots/screengrab android on multiple devices at the same time

adb+.sh

#!/bin/bash
# Script adb+
# Usage
# You can run any command adb provide on all your current devices
# ./adb+ <command> is the equivalent of ./adb -s <serial number> <command>
#
# Examples
# ./adb+ version
# ./adb+ install apidemo.apk
# ./adb+ uninstall com.example.android.apis

adb devices | while read line
do
    if [ ! "$line" = "" ] && [ `echo $line | awk '{print $2}'` = "device" ]
    then
        device=`echo $line | awk '{print $1}'`
        echo "$device $@ ..."
        adb -s $device $@ || echo "already uninstalled"
        
    fi
done

MultipleDeviceScreengrabFastfile

lane :build_for_screenshots do
      gradle(
          task: 'assemble',
          build_type: 'Screenshots'
      )
      gradle(
          task: 'assemble',
          build_type: 'ScreenshotsAndroidTest'
      )
  end

  lane :screenshots do

      def do_screenshot_on_device(device_name, device_type)
          # close all simulators
          sh('adb devices | grep emulator | cut -f1 | while read line; do adb -s $line emu kill; done')
          sh('sleep 3')

          # open simulator
          sh('emulator -avd %s > /dev/null 2>&1 &' % device_name)
          while true
              adb_output = adb(command: 'devices')
              puts('output of command' + adb_output)
              if adb_output.match(/emulator-([0-9]*)\tdevice/)
                  break
                  sh('sleep 3')
              end
              sh('sleep 3')     
          end

          # uninstall old tests
          begin
              sh('../adb+.sh uninstall "example.bundle.id.test"')
          rescue => ex
              UI.error(ex)
          end
          sh('../adb+.sh install ../app/build/outputs/apk/screenshots/app-screenshots.apk')
          sh('../adb+.sh install ../app/build/outputs/apk/androidTest/screenshots/app-screenshots-androidTest.apk')
          capture_android_screenshots(
              device_type: device_type
          )
      end

      do_screenshot_on_device('Nexus_10_API_28', 'tenInch')
      do_screenshot_on_device('Nexus_6_API_29', 'phone')

end

Screengrabfile

app_apk_path('./app/build/outputs/apk/screenshots/app-screenshots.apk')
tests_apk_path('./app/build/outputs/apk/androidTest/screenshots/app-screenshots-androidTest.apk')

output_directory('./fastlane/screenshots')

use_adb_root(true)
clear_previous_screenshots(true)

locales(['en-US'])

# clear all previously generated screenshots in your local output directory before creating new ones
skip_open_summary(true)

# For more information about all available options run
#   fastlane screengrab --help

I wanted to be able to automate taking screenshots on MULTIPLE DEVICES using fastlane. I couldn't quite find anything that did the trick. What my screenshots lane does it 1 by 1 launch emulators, wait for them to load, install tests, then run the fastlane screengrab action. You need to run build_for_screenshots before running screenshots. Be sure to replace the template bundle id with your own. Also note that normally you'd want to run with debug build variant but I'm using a build variant called "screenshots". I hope this is helpful to somebody! Feel free to post a question and I'll try to respond quickly.