diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml
new file mode 100644
index 0000000..048b1cf
--- /dev/null
+++ b/.github/FUNDING.yml
@@ -0,0 +1 @@
+github: [blueimp]
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..e44eb9e
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,10 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - run: shellcheck bin/*.sh
diff --git a/bin/android-emulator.sh b/bin/android-emulator.sh
index e9c301b..6d78302 100755
--- a/bin/android-emulator.sh
+++ b/bin/android-emulator.sh
@@ -1,12 +1,15 @@
 #!/bin/sh
 
 #
-# Starts the Android virtual device with a writeable filesystem.
+# Starts an Android virtual device with a writeable filesystem.
 # If the -hosts option is provided, replaces /etc/hosts on the device with the
 # given hosts file.
-# If no -avd option is given, starts the first AVD in the list.
+# If the -return option is given, returns to the caller when the emulator is
+# ready, otherwise waits for the emulator process to stop.
+# If no emulator -avd option is given, starts the first AVD in the list.
+# If no existing AVD is available, creates a new one.
 #
-# Usage: ./android-emulator.sh [-hosts file] [emulator options]
+# Usage: ./android-emulator.sh [-hosts file] [-return] [-- emulator options]
 #
 # Copyright 2019, Sebastian Tschan
 # https://blueimp.net
@@ -17,67 +20,130 @@
 
 set -e
 
+DEVICE_ID='pixel'
+SYSTEM_IMAGE_REGEXP='system-images;android-[0-9]*;google_apis;x86\>'
+WRITABLE_SYSTEM_IMAGE='system-images;android-28;google_apis;x86'
+SDCARD='512M'
+
 if [ -z "$ANDROID_HOME" ]; then
   echo 'Error: ANDROID_HOME is not defined.' >&2
   exit 1
 fi
 
-# shellcheck disable=SC2139
-alias emulator="$ANDROID_HOME/emulator/emulator"
-# shellcheck disable=SC2139
-alias adb="$ANDROID_HOME/platform-tools/adb"
+adb() {
+  "$ANDROID_HOME/platform-tools/adb" "$@"
+}
+
+emulator() {
+  "$ANDROID_HOME/emulator/emulator" "$@"
+}
+
+avdmanager() {
+  "$ANDROID_HOME/cmdline-tools/latest/bin/avdmanager" "$@"
+}
+
+sdkmanager() {
+  "$ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager" "$@"
+}
+
+normalize() {
+  echo "$1" | sed 's/[^a-z A-Z 0-9._-]/-/g'
+}
 
-# Echos first AVD listed
-avd() {
+get_avd() {
   emulator -list-avds | head -n 1
 }
 
-is_boot_completed() {
-  test "$(adb shell getprop sys.boot_completed | tr -d '\r')" = 1
+get_image() {
+  if [ -n "$HOSTS_FILE" ]; then
+    echo "$WRITABLE_SYSTEM_IMAGE"
+  else
+    sdkmanager --list | grep -o "$SYSTEM_IMAGE_REGEXP" | tail -1
+  fi
+}
+
+download_image() {
+  sdkmanager "$1"
 }
 
-has_avd_arg() {
+create_avd() {
+  echo 'Downloading system image ...'
+  download_image "$1"
+  echo 'System image downloaded.'
+  echo 'Creating Android Virtual Device ...'
+  avdmanager create avd \
+    --name "$(normalize "$DEVICE_ID-${1#*;}")" \
+    --package "$1" \
+    --device "$DEVICE_ID" \
+    --sdcard "$SDCARD"
+  echo 'Virtual Device created.'
+}
+
+has_arg() {
   while test $# -gt 0; do
-    test "$1" = -avd && return 0
+    test "$1" = "$ARG" && return 0
     shift
   done
   return 1
 }
 
-update_hosts_file() {
+has_system_prop() {
+  test "$(adb shell getprop "$1" | tr -d '\r')" = "$2"
+}
+
+wait_for_device() {
   echo 'Waiting for device to be ready ...'
   adb wait-for-device
-  while ! is_boot_completed; do
+  while ! has_system_prop sys.boot_completed 1; do
     sleep 1
   done
+  echo 'Device ready.'
+}
+
+update_hosts_file() {
   adb root
+  wait_for_device
   adb remount
   adb push "$1" /etc/hosts
   adb unroot
+  wait_for_device
 }
 
-shutdown() {
-  kill "$PID"
-}
-
-# Initiate a shutdown on SIGINT and SIGTERM:
-trap 'shutdown; exit' INT TERM
-
 if [ "$1" = -hosts ]; then
   HOSTS_FILE=$2
   shift 2
 fi
 
-if ! has_avd_arg "$@"; then
-  set -- -avd "$(avd)" "$@"
+if [ "$1" = -return ]; then
+  RETURN=true
+  shift
+fi
+
+if [ "$1" = -- ]; then
+  shift
+fi
+
+if ! ARG=-avd has_arg "$@"; then
+  if [ -z "$(get_avd)" ]; then
+    create_avd "$(get_image)"
+  fi
+  set -- -avd "$(get_avd)" "$@"
 fi
 
-set -- -writable-system "$@"
+if [ -n "$HOSTS_FILE" ]; then
+  set -- -writable-system "$@"
+fi
 
 emulator "$@" & PID=$!
 
+wait_for_device
+
 if [ -n "$HOSTS_FILE" ]; then
   update_hosts_file "$HOSTS_FILE"
 fi
 
+if [ "$RETURN" = true ]; then
+  exit
+fi
+
 wait "$PID"