Step: Write Some Basic Tests

At this point, I get a little nervous if I don’t have some tests. Fortunately, Elixir comes with a wonderful (and simple) testing framework called ExUnit.

Have a look at the file test/issues_test.exs.

 defmodule​ IssuesTest ​do
 use​ ExUnit.Case
  doctest Issues
 
  test ​"​​the truth"​ ​do
  assert 1 + 1 == 2
 end
 end

It acts as a template for all the test files you write. I just copy and paste the boilerplate into separate test files as I 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 ...

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