OptimumCredo.Check.Warning.SleepInTest (OptimumCredo v0.5.0)

Basics

This check has a base priority of low and works with any version of Elixir.

Explanation

Sleeping in tests slows the suite and hides races. Synchronise on a message (assert_receive) or an observable state change instead.

Bad:

Process.sleep(200)
assert render(view) =~ "done"

Good:

assert_receive {:done, _}

Genuine timer/debounce tests can be tagged with @moduletag :timing. This is a static heuristic over literal calls in test files.

Check-Specific Parameters

Use the following parameters to configure this check:

:functions

{module, function} pairs treated as sleeps.

This parameter defaults to [{Process, :sleep}, {:timer, :sleep}].

:wait_functions

Function names (local or remote) whose do/fn block is flagged when longer than max_wait_block_lines.

This parameter defaults to [:wait, :wait_until].

:max_wait_block_lines

Longest tolerated wait block, in lines.

This parameter defaults to 5.

:exempt_moduletag

A @moduletag atom that exempts the whole file (false disables).

This parameter defaults to :timing.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.