Writing Test Cases for GNU Hyperbole: Lessons Learned - EmacsConf 2023

Explore the intricacies of writing test cases for GNU Hyperbole in this EmacsConf 2023 talk. Dive into Emacs Lisp Regression Testing (ERT), learning to use assertions with `should`, run and debug test cases, and instrument functions on the fly. Discover mocking techniques, understand the use of hooks, and manage side effects in testing. Master essential tools like `with-temp-buffer`, `make-temp-file`, and `unwind-protect`. Learn to simulate input, run tests in batch mode, and implement test skipping. Gain valuable insights to enhance your Emacs Lisp testing skills and contribute effectively to open-source projects.

Syllabus

Introduction
ERT: Emacs Lisp Regression Testing
Assertions with `should`
Running a test case
Debug a test
Commercial break: Hyperbole
Instrument function on the fly
Mocking
cl-letf
Hooks
Side effects and initial buffer state
with-temp-buffer
make-temp-file
buffer-string
buffer-name
major-mode
unwind-protect
Input, with-simulated-input
Running all tests
Batch mode
Skipping tests
Conclusion