function testInit_PersistentIndices_NullableIndex() {
  var tableSchema = env.schema.table('tableF');
  var nonNullKeyRows = 4;
  var nullKeyRows = 5;
  var rows = getSampleRows(tableSchema, nonNullKeyRows, nullKeyRows);

  return simulatePersistedIndices(tableSchema, rows).then(
      function() {
        var prefetcher = new lf.cache.Prefetcher(lf.Global.get());
        return prefetcher.init(env.schema);
      }).then(
      function() {
        // Check that RowId index has been properly reconstructed.
        var rowIdIndex = env.indexStore.get(tableSchema.getRowIdIndexName());
        assertTrue(rowIdIndex instanceof lf.index.RowId);
        assertEquals(rows.length, rowIdIndex.getRange().length);

        // Check that remaining indices have been properly reconstructed.
        var indices = env.indexStore.getTableIndices(
            tableSchema.getName()).slice(1);
        indices.forEach(function(index) {
          assertTrue(index instanceof lf.index.NullableIndex);
          assertEquals(rows.length, index.getRange().length);
          assertEquals(nullKeyRows, index.get(null).length);
        });
      });
}
Tests that Prefetcher is correctly reconstructing persisted indices from the
backing store for the case where indices with nullable columns exist.
@return {!IThenable}