> For the complete documentation index, see [llms.txt](https://hanfak.gitbook.io/workspace/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hanfak.gitbook.io/workspace/testing-reading-maintaining/testing-1/property-based-testing.md).

# Property based testing

* See pragmatic programmer book
* A form of testing that is similar to table tests, but more flexible with random values which can be set within bounds, that tests the code.
* Focused on testing the contracts and invariants
  * what must be true, what must not be changed
  * removing edge cases and highlighting functions that leave data in an inconsistent state

## Issues

* Hard to pinpoint where the problem occured, what test case broke the test.
* Problems with setup, if unit testing, the controlling dependencies might be an issue.
  * Will need to be very tight in terms of the test cases for each set of behaviour
* USe of random values. Big issue, as a test may fail once, the pass again, lead to flakiness
  * Instead, find the test case, and values that caused the failure, and write a specific test for this, thus acting as a regression