Check these things still work

[simonharris]

Some of the most commonly used PLUnit predicates/options you might want to mention alongside assertion/1 and timeout/1 are:

• setup/1 and cleanup/1 — for per-test setup/teardown
• forall/2 — sometimes used in test definitions
• skip/1 — mark a test to be skipped
• fail / true — the standard test outcomes
• block/1 — optional, for controlling certain test execution contexts

[simonharris]

And for bonus points, create tests for them. Which would be like meta-meta-meta-tests by this point, but that's why we're here...