We need browser tests for adding a reference to a new statement that is currently added. Each test should try the add button within a statement group, as well as the add button under the existing statement groups. There should be a test trying to add an invalid reference. There should be tests trying to add empty references and expecting a disabled save button. All tests should make sure the state after clicking save is correct (i. e. which widgets are in edit mode, which toolbar buttons are present, what is the value of the references counter). All tests should reload the page to make sure the desired outcome is persistent.