Add LinkFactory to create links.

test/support/factories/link_factory.ex

@@ -0,0 +1,39 @@
+defmodule LinkShortener.Factories.LinkFactory do
+  use ExMachina
+
+  alias LinkShortener.Links
+  alias LinkShortener.Factories.UserFactory
+
+  def link_attrs_factory() do
+    %{
+      name: sequence(:name, &"name-#{&1}"),
+      url: "https://gitlab.com/KKlochko/link_shortener",
+      shorten: sequence(:shorten, &"shorten#{&1}"),
+    }
+  end
+
+  @doc """
+  Create a link that has a static url, a random name and a random shorten.
+  If there are no user_id in attrs, then a new user will be created.
+  """
+  def create_link(attrs \\ %{}) do
+    {:ok, link} =
+      link_attrs_factory()
+      |> put_new_user_id()
+      |> Map.merge(attrs)
+      |> Links.create_one()
+
+    link
+  end
+
+  defp put_new_user_id(attrs) do
+    if Map.has_key?(attrs, :user_id) do
+      attrs
+    else
+      user = UserFactory.create_user()
+
+      attrs
+      |> Map.put(:user_id, user.id)
+    end
+  end
+end