Some examples of how to use Erlang’s unit-testing framework, EUnit. Starting with simple examples and getting more advanced.

A simple EUnit test might look like this:

While you could specify each test with a single function, you can also use a test “instantiator” (or generator) and have it return a list.

What if we want to run some setup before a set of tests (and cleanup afterwards)?

We saw that setup runs setup/cleanup before all tests in a list. If you want to run some setup/cleanup before each test in a list, you can use foreach:

If you want to run some setup before (and cleanup after) a list of tests, and also some setup and cleanup for each test, you can nest setup and foreach:

The result from setup is passed to cleanup already. What if we want to pass it to each of our tests? It’s a bit awkward, but it looks like the following:

Similar to passing the result from {setup, Setup, ... to each test, you can also pass the result from {foreach, Setup, ... to each test, but there are some differences.

In several of the previous posts, for example Using ‘setup’, I’ve started a server in suite_setup/0 and needed to kill it in suite_cleanup/1. I showed a simple way to do that, but it’s not the best. Here’s a better way to do it.

In earlier posts, Passing the result from ‘foreach’ and Passing the result from ‘setup’, I showed how to (awkwardly) pass the result from the setup function to the test functions.