skip Saucelabs tests on PRs, because secret ENV vars are not supported currently for PRs

scripts/test-app.sh

@@ -3,6 +3,11 @@ set -e
 
 ROOT="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"/..
 
+if [ $CI == "true" ] && ([ -z $SAUCE_USERNAME ] || [ -z $SAUCE_ACCESS_KEY ]); then
+  echo "Skipping CI tests, because Saucelabs credentials are not set.";
+  exit 0;
+fi
+
 pushd $ROOT
 ./node_modules/.bin/mocha ./test/app-mocha-specs/test.js "$@"
 popd

scripts/upload-artifact.sh

@@ -5,6 +5,11 @@ PLATFORM=$([[ "${@#--android}" = "$@" ]] && echo "ios" || echo "android")
 ROOT="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"/..
 TEMP=$ROOT/temp
 
+if [ -z $SAUCE_USERNAME ] || [ -z $SAUCE_ACCESS_KEY ]; then
+  echo "Skipping uploading artifact, because Saucelabs credentials are not set.";
+  exit 0;
+fi
+
 if [ $PLATFORM = "android" ]; then
   curl -u $SAUCE_USERNAME:$SAUCE_ACCESS_KEY \
       -X POST \