ert

What problem does it solve?

ERT provides a structured framework for defining and running Emacs Lisp tests, enabling interactive and batch testing, with helpful failure reports to reduce debugging time and guard against regressions.

Core Features & Use Cases

• Test Definitions: Write tests with ert-deftest, including optional docstrings and metadata.
• Assertions: Use should, should-not, and should-error for precise validations and error checks.
• Test Execution: Run tests interactively via M-x ert or in batch mode for CI/CD workflows.
• Debugging: Integrated debugging support with backtraces and reruns to quickly locate and fix issues.
• Mocking & Fixtures: Leverage common patterns (e.g., cl-letf, unwind-protect) to isolate tests.

Quick Start

To get started:

• Require the library: (require 'ert)
• Define a simple test:

  (ert-deftest my-test ()
    "Simple test."
    (should (= 1 1)))
  

• Run tests interactively: M-x ert RET t RET
• Run tests in batch mode for CI: emacs -batch -l ert -f ert-run-tests-batch-and-exit
• Review results in the ERT buffer and press d to debug a failing test.