Update the Authentication.

test/support/conn_case.ex

@@ -35,4 +35,30 @@ defmodule LinkShortenerWeb.ConnCase do
     LinkShortener.DataCase.setup_sandbox(tags)
     {:ok, conn: Phoenix.ConnTest.build_conn()}
   end
+
+  @doc """
+  Setup helper that registers and logs in users.
+
+      setup :register_and_log_in_user
+
+  It stores an updated connection and a registered user in the
+  test context.
+  """
+  def register_and_log_in_user(%{conn: conn}) do
+    user = LinkShortener.AccountsFixtures.user_fixture()
+    %{conn: log_in_user(conn, user), user: user}
+  end
+
+  @doc """
+  Logs the given `user` into the `conn`.
+
+  It returns an updated `conn`.
+  """
+  def log_in_user(conn, user) do
+    token = LinkShortener.Accounts.generate_user_session_token(user)
+
+    conn
+    |> Phoenix.ConnTest.init_test_session(%{})
+    |> Plug.Conn.put_session(:user_token, token)
+  end
 end

test/support/fixtures/accounts_fixtures.ex

@@ -0,0 +1,31 @@
+defmodule LinkShortener.AccountsFixtures do
+  @moduledoc """
+  This module defines test helpers for creating
+  entities via the `LinkShortener.Accounts` context.
+  """
+
+  def unique_user_email, do: "user#{System.unique_integer()}@example.com"
+  def valid_user_password, do: "hello world!"
+
+  def valid_user_attributes(attrs \\ %{}) do
+    Enum.into(attrs, %{
+      email: unique_user_email(),
+      password: valid_user_password()
+    })
+  end
+
+  def user_fixture(attrs \\ %{}) do
+    {:ok, user} =
+      attrs
+      |> valid_user_attributes()
+      |> LinkShortener.Accounts.register_user()
+
+    user
+  end
+
+  def extract_user_token(fun) do
+    {:ok, captured_email} = fun.(&"[TOKEN]#{&1}[TOKEN]")
+    [_, token | _] = String.split(captured_email.text_body, "[TOKEN]")
+    token
+  end
+end