Fix smoke test (#42022)

dev/bots/firebase_testlab.sh

@@ -3,15 +3,35 @@
 # The tests to run on Firebase Test Lab.
 # Currently, the test consists on building an Android App Bundle and ensuring
 # that the app doesn't crash upon startup.
+#
+# When adding a test, ensure that there's at least a `print()` statement under lib/*.dart.
 tests=(
   "dev/integration_tests/release_smoke_test"
   "dev/integration_tests/abstract_method_smoke_test"
 )
 
+# The devices where the tests are run.
+#
+# To get the full list of devices available, run:
+#     gcloud firebase test android models list
+devices=(
+  # Pixel 3
+  "model=blueline,version=28"
+  "model=blueline,version=Q-beta-3"
+
+  # Moto Z XT1650
+  "model=griffin,version=24"
+)
+
 set -e
 
 GIT_REVISION=$(git rev-parse HEAD)
 
+DEVICE_FLAG=""
+for device in ${devices[*]}; do
+  DEVICE_FLAG+="--device $device "
+done
+
 # New contributors will not have permissions to run this test - they won't be
 # able to access the service account information. We should just mark the test
 # as passed - it will run fine on post submit, where it will still catch
@@ -30,21 +50,27 @@ function test_app_bundle() {
   pushd "$@"
   ../../../bin/flutter build appbundle --target-platform android-arm,android-arm64
 
-  # Firebase Test Lab tests are currently known to be failing with
-  # "Firebase Test Lab infrastructure failure: Error during preprocessing"
-  # Remove "|| exit 0" once the failures are resolved
-  # https://github.com/flutter/flutter/issues/36501
+  aab="build/app/outputs/bundle/release/app-release.aab"
+
+  # If the app bundle doesn't exist, then exit with code 1.
+  if [ ! -f "$aab" ]; then
+    exit 1
+  fi
 
   # Run the test.
-  gcloud firebase test android run --type robo \
-    --app build/app/outputs/bundle/release/app.aab \
+  gcloud firebase test android run \
+    --type robo \
+    --app "$aab" \
     --timeout 2m \
     --results-bucket=gs://flutter_firebase_testlab \
-    --results-dir="$@"/"$GIT_REVISION"/"$CIRRUS_BUILD_ID" || exit 0
+    --results-dir="$@"/"$GIT_REVISION"/"$CIRRUS_BUILD_ID" \
+    $DEVICE_FLAG
 
+  rm -f /tmp/logcat
+  gsutil cat gs://flutter_firebase_testlab/"$@"/"$GIT_REVISION"/"$CIRRUS_BUILD_ID"/*/logcat > /tmp/logcat
   # Check logcat for "E/flutter" - if it's there, something's wrong.
-    gsutil cp gs://flutter_firebase_testlab/"$@"/"$GIT_REVISION"/"$CIRRUS_BUILD_ID"/walleye-26-en-portrait/logcat /tmp/logcat
   ! grep "E/flutter" /tmp/logcat || false
+  # Check logcat for "I/flutter" - This is in the log if there's a print statement under lib/*.dart.
   grep "I/flutter" /tmp/logcat
   popd
 }

dev/integration_tests/abstract_method_smoke_test/lib/main.dart

 import 'package:flutter/material.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
 
-void main() => runApp(MyApp());
+void main() {
+  runApp(MyApp());
+  print('Test suceeded');
+}
 
 class MyApp extends StatelessWidget {
   @override

dev/integration_tests/release_smoke_test/android/build.gradle

@@ -5,7 +5,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.2.1'
+        classpath 'com.android.tools.build:gradle:3.5.0'
     }
 }
 

dev/integration_tests/release_smoke_test/android/gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.1-all.zip