tests: in Travis, also run the backend tests

This change introduces automatic execution of the backend tests in Travis.

Implements #2351.

tests/frontend/travis/runnerBackend.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# do not continue if there is an error
+set -eu
+
+# source: https://stackoverflow.com/questions/59895/get-the-source-directory-of-a-bash-script-from-within-the-script-itself#246128
+MY_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null && pwd )"
+
+# reliably move to the etherpad base folder before running it
+cd "${MY_DIR}/../../../"
+
+# start Etherpad, assuming all dependencies are already installed.
+#
+# This is possible because the "install" section of .travis.yml already contains
+# a call to bin/installDeps.sh
+echo "Running Etherpad directly, assuming bin/installDeps.sh has already been run"
+node node_modules/ep_etherpad-lite/node/server.js "${@}" > /dev/null &
+
+echo "Now I will try for 15 seconds to connect to Etherpad on http://localhost:9001"
+
+# wait for at most 15 seconds until Etherpad starts accepting connections
+#
+# modified from:
+# https://unix.stackexchange.com/questions/5277/how-do-i-tell-a-script-to-wait-for-a-process-to-start-accepting-requests-on-a-po#349138
+#
+(timeout 15 bash -c 'until echo > /dev/tcp/localhost/9001; do sleep 0.5; done') || \
+    (echo "Could not connect to Etherpad on http://localhost:9001" ; exit 1)
+
+echo "Successfully connected to Etherpad on http://localhost:9001"
+
+# just in case, let's wait for another second before going on
+sleep 1
+
+# a copy of settings.json is necessary for the backend tests to work
+cp settings.json.template settings.json
+
+# run the backend tests
+echo "Now run the backend tests"
+cd src
+npm run test
+exit_code=$?
+
+kill $!
+sleep 5
+
+exit $exit_code