How to Write Doctests in Elixir

If you want to make doctests in Elixir, then it’s really simple. This is going to be a short post, assuming you already have Elixir installed and have started your own project running mix new projectname.

In your .exs file, add this very specific syntax to your code in the form of a comment.

@doc """

## Examples 

            iex>1+1 #insert 3 tabs
            2 
    #make sure to have a new line here
"""

This will add whatever example you list to your doctests automatically.

So, when you run mix test, it will run those test files to see if that is the result of your input.

In this case, 1+1 calculation equals 2. So, the result would be 2. This test would pass.

Try and run it!

Use the mix test command in your CLI.

You can write more doc tests by adding another segment of @doc plus the quotes for comment syntax and the exact syntax in the above example duplicated with a different example!

Congratulations! You now know how to write doctests in Elixir projects!

Published 25 Apr 2019

founder && full stack && ethereum developer.
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