Add testcases for invalid indexer_language Set invalid indexer_language and test: indexer = "" and xapian not able to be loaded -> no exception indexer = native -> no exception indexer = xapian -> ValueError exception Also test reset to verify that indexer_language is reset to english from NO_LANG. Also create helper method to munge config.ini for each test case. Changed all test to use it. Also moved doc from class to the test that it described.