Write Some Basic Tests

Elixir comes with a wonderful and simple testing framework called ExUnit.

Have a look at this code:

defmodule IssuesTest do
  use ExUnit.Case
  doctest Issues

  test "greets the world" do
    assert Issues.hello() == :world
  end
end

It acts as a template for all the test files we write. We just copy and paste the boilerplate into separate test files as we need them. So, let’s write tests for our CLI module, putting those tests into the file test/cli_test.exs. (Test file names must end with _test.) We’ll test that the option parser successfully detects the -h and --help options and that it returns the arguments otherwise. We’ll also check that it supplies a default value for the count if only two arguments are given.

Note: We may get a loading module/bad file error on executing the mix test command the very first time because it can take some time to compile this code. We won’t see it when we rerun this command.

Run the mix test command to execute both codes given below.