function testKeyOfIndex_NullableField() {
  var getSchema = function() {
    var tableBuilder = new lf.schema.TableBuilder('Table');
    tableBuilder.
        addColumn('datetime', lf.Type.DATE_TIME).
        addColumn('integer', lf.Type.INTEGER).
        addColumn('number', lf.Type.NUMBER).
        addColumn('string', lf.Type.STRING).
        addColumn('boolean', lf.Type.BOOLEAN).
        addNullable(['datetime', 'integer', 'number', 'string', 'boolean']).
        addIndex('idx_datetime', ['datetime']).
        addIndex('idx_integer', ['integer']).
        addIndex('idx_number', ['number']).
        addIndex('idx_string', ['string']).
        addIndex('idx_boolean', ['boolean']);
    return tableBuilder.getSchema();
  };
  var tableSchema = getSchema();
  var row = tableSchema.createRow();

  tableSchema.getIndices().forEach(function(indexSchema) {
    assertNull(row.keyOfIndex(indexSchema.getNormalizedName()));
  });
}
Tests that keyOfIndex() is correctly handling nullable fields.