Elixir ExUnit helper for asserting that two maps (or structs) have equal values at the specified paths.

test_helpers.ex

defmodule TestHelpers do
  import ExUnit.Assertions, only: [assert: 2, flunk: 1]

  @spec assert_nested_paths_equal(map(), map(), [atom()]) :: :ok
  def assert_nested_paths_equal(map1, map2, paths) do
    Enum.each(paths, fn path ->
      with {:ok, value1} <- get_nested_field(map1, path),
           {:ok, value2} <- get_nested_field(map2, path) do
        assert value1 == value2,
               "Path #{inspect(path)} differs: #{inspect(value1)} != #{inspect(value2)}"
      else
        {:error, key} ->
          flunk("Path missing key: #{inspect(path)} (key: #{inspect(key)})")
      end
    end)
  end

  defp get_nested_field(struct, path) when is_list(path) do
    Enum.reduce_while(path, {:ok, struct}, fn key, {:ok, acc} ->
      case Map.fetch(acc, key) do
        {:ok, value} -> {:cont, {:ok, value}}
        :error -> {:halt, {:error, key}}
      end
    end)
  end
end