Sources: 
  - Software Testing course at ITMO university by Kochubeev Nikolay Sergeevich 
  - [[https://dzone.com/articles/first-principles-solid-rules-for-tests]]

====== FIRST ======

First: Fast, Isolated, Repeatable, Self-validating, Timely.

Even a properly structured [[software_testing|test]] ([[arrange_act_assert|AAA]] or [[given_when_then|GWT]]) can be useless: it is slow, environment-dependent, or requires manual verification. FIRST helps to avoid this by setting clear quality criteria.

==== Fast ====

The tests must be as fast as possible. They're supposed to run by all members on the team for each task, there can be hundreds of them for each commit.

==== Isolated ====

The tests should not depend on one another. Any dependencies to the database, network, clock must be emulated by the interface.

==== Repeatable ====

A test must give the same result in every environment. 

==== Self-validating ====

Tests must be able to auto-detect if it passed or not.

==== Timely ====

The tests must be written before or during production. Otherwise you might end up testing only positives, forgoing testing the actual errors that influence production.