Add evaluate tx

lib/xogmios/tx_submission.ex

@@ -29,18 +29,37 @@ defmodule Xogmios.TxSubmission do
   """
   @spec submit_tx(pid() | atom(), String.t()) :: {:ok, any()} | {:error, any()}
   def submit_tx(client \\ __MODULE__, cbor) do
-    with {:ok, message} <- build_message(cbor),
-         {:ok, %Response{} = response} <- call_tx_submission(client, message) do
+    with {:ok, message} <- build_submit_message(cbor),
+         {:ok, %Response{} = response} <- call(client, message) do
       {:ok, response.result}
     end
   end
 
-  defp build_message(cbor),
+  @doc """
+  Evaluates the execution units of scripts present in a given transaction.
+
+  This function is synchronous and takes two arguments:
+
+  1. (Optional) A process reference. If none given, it defaults to the linked process `__MODULE__`.
+  2. The CBOR of a transaction. Unlike `submit_tx/1`, this function does not expect the transaction to be signed. Please refer to the [official Ogmios docs](https://ogmios.dev/mini-protocols/local-tx-submission/#evaluating-transactions) for more details on the type of transaction that is accepted.
+  """
+  @spec evaluate_tx(pid() | atom(), String.t()) :: {:ok, any()} | {:error, any()}
+  def evaluate_tx(client \\ __MODULE__, cbor) do
+    with {:ok, message} <- build_evaluate_message(cbor),
+         {:ok, %Response{} = response} <- call(client, message) do
+      {:ok, response.result}
+    end
+  end
+
+  defp build_submit_message(cbor),
     do: {:ok, Messages.submit_tx(cbor)}
 
-  defp call_tx_submission(client, message) do
+  defp build_evaluate_message(cbor),
+    do: {:ok, Messages.evaluate_tx(cbor)}
+
+  defp call(client, message) do
     try do
-      case GenServer.call(client, {:submit_tx, message}, @tx_submit_timeout) do
+      case GenServer.call(client, {:send, message}, @tx_submit_timeout) do
         {:ok, response} -> {:ok, response}
         {:error, reason} -> {:error, reason}
       end
@@ -69,7 +88,7 @@ defmodule Xogmios.TxSubmission do
       end
 
       @impl true
-      def handle_call({:submit_tx, message}, from, state) do
+      def handle_call({:send, message}, from, state) do
         {:store_caller, _from} = send(state.ws_pid, {:store_caller, from})
         :ok = :websocket_client.send(state.ws_pid, {:text, message})
         {:noreply, state}

lib/xogmios/tx_submission/messages.ex

@@ -25,6 +25,23 @@ defmodule Xogmios.TxSubmission.Messages do
     json
   end
 
+  def evaluate_tx(cbor) do
+    json = ~s"""
+    {
+      "jsonrpc": "2.0",
+      "method": "evaluateTransaction",
+      "params": {
+          "transaction": {
+            "cbor": "#{cbor}"
+          }
+      }
+    }
+    """
+
+    validate_json!(json)
+    json
+  end
+
   defp validate_json!(json) do
     case Jason.decode(json) do
       {:ok, _decoded} -> :ok