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Ensuring Elixir Application Performance with Testing and ExUnit

Refactoring Tests to Be Self-updating

Learn how to write self-updating tests for a basic schema.

We'll cover the following...

Now that we have guaranteed our test’s accuracy in the previous lesson let’s refactor our test to be self-updating.

Creating a self-updating test

Before we write our first test, we’ll write a helper function at the bottom of our test file after all the describe blocks.

Helper function

The new function will be called valid_params/1:

Elixir
#file path -> testing_ecto/test/schemas/user_basic_schema_2_test.exs
#add this code at the indicated place mentioned in comments of 
#testing_ecto/test/schemas/user_basic_schema_2_test.exs 
#in the playground widget
defp valid_params(fields_with_types) do
  valid_value_by_type = %{
    date: fn -> to_string(Faker.Date.date_of_birth()) end,
    float: fn -> :rand.uniform() * 10 end,
    string: fn -> Faker.Lorem.word() end
  }
  for {field, type} <- fields_with_types, into: %{} do
    {Atom.to_string(field), valid_value_by_type[type].()}
  end
end

The return value of this function is a map that’s functionally identical to the params we had in our success test in our previous iteration of this file (user_basic_schema_1_test.exs). It’s just a string-keyed map of valid parameters, but it’s built dynamically based on the list of fields and types passed to it.

Faker

We’re using a new library, Faker:

Faker’s sole purpose is to provide realistically shaped data, often to use as fake data for ...