Sources: 
  - Software Testing course at ITMO university by Kochubeev Nikolay Sergeevich 
  - [[https://martinfowler.com/bliki/GivenWhenThen.html]]

====== Given When Then (GWT) ======

GWT is an approach to [[software_testing|tests]] and scenarios which comes from BDD (Behavior-Driven Development). It helps testers, analysts and for businesses.

GWT is made up of 3 parts:

  - Given: the context: pre-conditions for the behavior.
  - When: the behavior being described.
  - Then: the changes expected due to the behavior.

==== Given ====

  * Is a description of the prerequisites of the test.
  * Creates the desired system state.
  * Is formulated in the language of the subject area.

==== When ====

  * A description of one key action.
  * It should be clear which trigger is being checked.

==== Then ====

  * Description of the expected result.
  * The focus is on the observed behavior, not the implementation.


==== Comparing AAA and GWT ====

[[arrange_act_assert|AAA]] and GWT are very similar:

  * Arrange = Given.
  * Act = When.
  * Assert = Then.

AAA is used in testing code, and GWT is used in BDD scenarios, where it's important for them to be readable for the business.

==== Best practices ====

  - Each test is one scenario.
  - Formulate Given/When/Then in terms of the subject area, not the implementation.
  - Use the following method names: Given_X_When_Y_Then_Z.
  - Avoid "and" in the sections — this is a sign that the test is too difficult.