py311-expecttest

Implementation of expect tests

The expecttest library implements expect tests (also known as "golden" tests). Expect tests are a method of writing tests where instead of hard-coding the expected output of a test, you run the test to get the output, and the test framework automatically populates the expected output. If the output of the test changes, you can rerun the test with the environment variable EXPECTTEST_ACCEPT=1 to automatically update the expected output.