Run karma task only in test environment

and fails otherwise, as it needs the defaults defined in test environment

script/ci/run_js_tests.sh

@@ -14,4 +14,4 @@ echo "--- Bundling"
 bundle install
 
 echo "--- Running tests"
-bundle exec rake karma:run
+./script/karma run

script/karma

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+task="$1"
+
+if [ "$task" = "run" ] || [ "$task" = "start" ]; then
+  exec bundle exec rake "karma:$task" RAILS_ENV=test
+else
+  echo "Usage:"
+  echo "  $0 run   # to run the tests once"
+  echo "  $0 start # to run the tests on every file modification"
+  exit 1
+fi
+