Sooner or later we will need to add tests to check for regressions.

I propose the following three kinds of tests:

• Function unit tests (mainly for the parsing functions)
• I/O testing: simulate a client sending requests from a different process and check the responses are correct
• Internal state testing: simulate a client sending requests from a different process and check our internal state (number of documents, text of documents, latest sane_text of documents etc.)