testExecOnLoad() {
    let mm = getModuleManager({'a': [], 'b': [], 'c': []});
    mm.setLoader(createSuccessfulNonBatchLoader(mm));
    execOnLoad(mm);

    mm = getModuleManager({'a': [], 'b': [], 'c': []});
    mm.setLoader(createSuccessfulBatchLoader(mm));
    mm.setBatchModeEnabled(true);
    execOnLoad(mm);
  }
Tests loading a module under different conditions i.e. unloaded
module, already loaded module, module loaded through user initiated
actions, synchronous callback for a module that has been already
loaded. Test both batch and non-batch loaders.