How To Write Phoenix and Elixir Doc Tests
Over the course of a couple of weeks of working with Phoenix and Elixir, I was asked to document and possibly provide some tests with respect to a code base I was working on.
It’s actually pretty straightforward to setup.
Step 1: Set up a documentation block
First setup a documentation block in the module you are testing.
@doc """ Return a base url to query the YT api ## Example iex> Yt.fetch_url("playlists") "https://www.googleapis.com/youtube/v3/playlists" iex> Yt.to_integer_or_default("4") 4 """
Add the iex> prompt just like in the above code with a call to the method you’re testing. On the next line, there should be the result you’re expecting.
Step 2: Add “doctest” to your test file with the module name as an argument
In my case, I created a file in test/documenation_test.exs.
defmodule DocumentationTest.Test do use ExUnit.Case doctest Yt end
Step 3: Make sure the method you’re testing is public
You can’t test private methods, so don’t bother.
Step 4: Run the tests
Run your documentation tests just like you would any other test.
mix test test/documentation_test.exs
You should see successful output if your tests passed.
Documentation based testing is a handy way to test and document your Phoenix application at the same time. Give it a try!