testLoadMultipleWithDuplicates() {
    const mm = getModuleManager({'a': [], 'b': []});
    mm.setBatchModeEnabled(true);
    mm.setLoader(createSuccessfulBatchLoader(mm));

    const listWithDuplicates = ['a', 'a', 'b'];
    mm.loadMultiple(listWithDuplicates);
    assertArrayEquals(
        'loadMultiple should not modify its input', ['a', 'a', 'b'],
        listWithDuplicates);
  }
Tests that when loading multiple modules, the input array is not
modified when it has duplicates.