createTable = function(tableName) {
    return new lf.schema.TableBuilder(tableName).
        addColumn('id', lf.Type.STRING).
        addColumn('name', lf.Type.STRING).
        addPrimaryKey(['id']).
        addIndex('idxName', [{'name': 'name', 'order': lf.Order.DESC}]).
        getSchema();
  }
Dummy schema implementation to be used in tests.
@implements {lf.schema.Database}
@constructor