Code for step 5

lib/load_generator.ex

@@ -0,0 +1,34 @@
+defmodule PaymentsClient.LoadGenerator do
+  alias PaymentsClient.{MockAPI, RateLimiter}
+
+  def create_requests(num_requests) do
+    1..num_requests
+    |> Enum.each(fn _ ->
+      {request_handler, response_handler} = generate_random_request()
+
+      RateLimiter.make_request(request_handler, response_handler)
+    end)
+  end
+
+  defp generate_random_request do
+    case Enum.random(1..3) do
+      1 ->
+        {
+          {MockAPI, :create_payment, [123, %{cc_number: 1_234_567_890, exp_date: "01/28"}]},
+          {MockAPI, :handle_create_payment}
+        }
+
+      2 ->
+        {
+          {MockAPI, :delete_payment, [123, 456]},
+          {MockAPI, :handle_delete_payment}
+        }
+
+      3 ->
+        {
+          {MockAPI, :charge_payment, [123, 456, 10.00]},
+          {MockAPI, :handle_charge_payment}
+        }
+    end
+  end
+end