function test_IsNull_NonIndexed() {
  var tableSchema = db.getSchema().getDummyTable();
  // Ensure that the 'datetime' field is not indexed.
  assertEquals(0, tableSchema.datetime.getIndices().length);
  var sampleData = generateSampleDummyData();

  /**
   * Select records to the database.
   * @return {!IThenable}
   */
  var selectFn = function() {
    return db.
        select().
        from(tableSchema).
        where(tableSchema.datetime.isNull()).
        exec();
  };

  return selectFn().then(
      function(result) {
        assertEquals(1, result.length);

        // Expecting the second sample row to have been retrieved.
        var retrievedEmployee = result[0];
        assertEquals(sampleData[1].getString(), retrievedEmployee.string);
      });
}
Tests the case where an isNull() predicate is used on a non-indexed field.
@return {!IThenable}