Ensuring Elixir Application Performance with Testing and ExUnit/

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Testing Create Operation

Testing Create Operation

Learn how to test queries in the testing_ecto application.

We'll cover the following...

We’re going to start by looking at part of the logic file with our queries. The file, called Users, contains the basic CRUD actions:

  • create/1
  • get/1
  • update/2
  • delete/1

The file lib/users/users.ex in testing_ecto is provided:

create/1

The create/1 function in testing_ecto/lib/users/users.ex look like this:

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#file path -> testing_ecto/lib/users/users.ex
#add this code at the indicated place mentioned in comments of testing_ecto/lib/users/users.ex
#in the playground widget
  def create(params) do
    params
    |> User.create_changeset()
    |> Repo.insert()
  end

It’s pretty basic, as most CRUD queries are. As a result, testing it won’t be very complicated, either.

Writing tests

Let’s set up a new file at testing_ecto/test/users/users_test.ex.

Success path test

First, we’ll write a success path test.

In it, set up a basic test file structure and then add a describe block for create/1 and our first test:

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#file path -> testing_ecto/test/users/users_test.exs
#add this code at the indicated place mentioned in comments of testing_ecto/test/users/
#users_test.exs in the playground widget
  
  
  setup do
    Ecto.Adapters.SQL.Sandbox.checkout(TestingEcto.Repo) 
  end
  describe "create/1" do
    test "success: it inserts a user in the db and returns the user" do
      params = Factory.string_params_for(:user)  
      now = DateTime.utc_now()  
      assert {:ok, %User{} = returned_user} = Users.create(params)  
      user_from_db = Repo.get(User, returned_user.id)  
      assert returned_user == user_from_db  
      mutated = ["date_of_birth"]
      for {param_field, expected} <- params,
          param_field not in mutated do
        schema_field = String.to_existing_atom(param_field)
        actual = Map.get(user_from_db, schema_field)
        assert actual == expected,
               "Values did not match for field: #{param_field}\nexpected: #{
                 inspect(expected)
               }\nactual: #{inspect(actual)}"
      end
      expected_dob = Date.from_iso8601!(params["date_of_birth"])
      assert user_from_db.date_of_birth == expected_dob
      assert user_from_db.inserted_at == user_from_db.updated_at
      assert DateTime.compare(now, user_from_db.inserted_at) == :lt  
    end
  end

Let’s go through our test step-by-step:

  • Observe the common setup block at line 7 ...