testExecOnLoadWhilePreloadingAndViceVersa() {
    let mm = getModuleManager({'c': [], 'd': []});
    mm.setLoader(createSuccessfulNonBatchLoader(mm));
    execOnLoadWhilePreloadingAndViceVersa(mm);

    mm = getModuleManager({'c': [], 'd': []});
    mm.setLoader(createSuccessfulBatchLoader(mm));
    mm.setBatchModeEnabled(true);
    execOnLoadWhilePreloadingAndViceVersa(mm);
  }
Test preloading modules and ensure that the before load, after load
and set load called are called only once per module.