Phoenix provides the following helper when you use AppName.DataCase in your tests
This doesn’t give you the “first” error, but you can use it to check errors in any order you’d like.
@doc """
A helper that transforms changeset errors into a map of messages.
assert {:error, changeset} = Accounts.create_user(%{password: "short"})
assert "password is too short" in errors_on(changeset).password
assert %{password: ["password is too short"]} = errors_on(changeset)
"""
def errors_on(changeset) do
Ecto.Changeset.traverse_errors(changeset, fn {message, opts} ->
Regex.replace(~r"%{(\w+)}", message, fn _, key ->
opts |> Keyword.get(String.to_existing_atom(key), key) |> to_string()
end)
end)
end