Elixir Course Testing

Elixir Course Testing And Documentation

Documentation

Two types:

Module documentation: purpose of module
Function documentation: purpose of individual functions

Using ex_doc as the required module, add {:ex_doc, "~> 0.21.1"}, to you deps (or the latest version) and after fetching deps, run mix docs to generate the documentation.

Documentation can then be found at doc/index.html.

Examples:

defmodule ModuleName.Queries do
  @moduledoc """
  Provides Ecto queries for querying important Action Framework requirement.
  """

  import Ecto.Query

  @doc """
  Does a thing

  ## Examples

      iex> query = "Hello, World!"
      iex> query
      "Hello, World!"
  """
  def hello_world() do
    "Hello, World!"
  end
end

Elixir Testing

There are two distinct types of tests we can write:

Assertion tests
Doc testing

Example Test

defmodule Cards do
  def create_deck do
    values = ["Ace", "Two"]
    suits = ["Spades", "Clubs"]
  end

  # ... more
end

Testing can be considered a first-class citizen. It comes built into Elixir.

When you generate the project with mix, you get a test folder put in automatically.

The cards_test.exs file is specifically built for testing the functions used in cards_test.exs.

Note that running elixir test will end up with two tests run with 0 failures.

The "mystery" test cmes frm the @doc tag ## Examples - it will run that chunk of code as if it is a test!

Example, the following code will run as a test:

@doc """
  Divides a deck ito a hand and the remainder of the deck.

## Examples

    iex> deck = Card.create_deck
    iex> {hand, deck} = Cards.deal(deck, 1)
    iex> hand
    ["Ace of Spaces"]
"""
def deal(deck, hand_size) do
  Enum.split(deck, hand_size)
end

Important Tidbits

Worth noting for a basic Elixir test example:

defmodule CardsTest do
  use ExUnit.Case
  doctest Cards
end

doctest is used for testing the documentation examples.

Case Tests

For the terms use ExUnit.Case:

defmodule CardsTest do
  use ExUnit.Case
  doctest Cards

  test "create_deck makes 20 cards" do
    deck_length = length(Cards.create_deck)
    assert deck_length == 20
  end
end

Assert vs Refute

The refute keyword is just the opposite of assert.