code: function(data, escapeHeaderValues) {
      const onFrame = jasmine.createSpy('onFrame');
      const onIncomingPing = jasmine.createSpy('onIncomingPing');
      const parser = new StompJs.Parser(onFrame, onIncomingPing);
  
      parser.parseChunk(data);
  
      const rawFrame = onFrame.calls.first().args[0];
      return StompJs.FrameImpl.fromRawFrame(rawFrame, escapeHeaderValues);
    }
docs: un-marshall a data chunk, for ease of matching body is converted to string