Test

ExUnit

ExUnit is Elixir's built-in testing framework. It's integrated with Mix.

A basic example

1. Code to Test (lib/my_math.ex)

defmodule MyMath do
  def add(a, b) do
    a + b
  end
end

2. Test File (test/my_math_test.exs)

defmodule MyMathTest do
  use ExUnit.Case
  doctest MyMath  # Run doctests found in lib/my_math.ex (optional but good practice)
  
  test "adds two numbers" do
    assert MyMath.add(1, 2) == 3
    assert MyMath.add(0, 0) == 0
    assert MyMath.add(-1, 1) == 0
  end
end

3. Running Tests

mix test

Mix will compile your code and run all files matching test/*_test.exs. To test a single file:

mix test test/my_math_test.exs

To get coverage reporting:

mix --cover test

More

• describe
• setup

Mock

Mock is a testing library that allows you to temporarily replace the behavior of modules or functions during tests.