function getSchemaWithoutForeignKeys() {
  var schemaBuilder = lf.schema.create('contexttest', 1);
  schemaBuilder.createTable('TableA').
      addColumn('id', lf.Type.STRING);
  schemaBuilder.createTable('TableB').
      addColumn('id', lf.Type.STRING);
  return schemaBuilder.getSchema();
}
@return {!lf.schema.Database} A schema where no foreign keys exist.