gistfile1.txt

====================================================================================
new test:

  test "converts unique_constraint on username to error" do
    %User{}
    |> User.registration_changeset(@valid_attrs)
    |> Repo.insert!()
    Repo.all(User)
    |> IO.inspect()
    attrs = Map.put(@test_attrs, :username, "user")
    changeset = User.registration_changeset(%User{}, attrs)

    assert {:error, changeset} = Repo.insert(changeset)
    assert {:username, {"has already been taken", []}} in changeset.errors
  end

================================================================================================
result:


[%Storybook.User{__meta__: #Ecto.Schema.Metadata<:loaded, "users">,
  email: "[email protected]", id: 30,
  inserted_at: #Ecto.DateTime<2016-10-17 09:47:00>, name: nil, password: nil,
  password_hash: "$2b$12$j2xU4omjt3YYyxr5cl35e.L6B79dobbOI7bTjuUtIyyDy8JUskb.K",
  updated_at: #Ecto.DateTime<2016-10-17 09:47:00>, username: "user"}]
  
and test passes.