use default max_priority_fee (#106)

Author: wchenNL

lib/ethers/transaction.ex

@@ -19,7 +19,7 @@ defmodule Ethers.Transaction do
     gas_price: nil,
     hash: nil,
     max_fee_per_gas: nil,
-    max_priority_fee_per_gas: "0x0",
+    max_priority_fee_per_gas: nil,
     nonce: nil,
     signature_r: nil,
     signature_s: nil,
@@ -58,7 +58,7 @@ defmodule Ethers.Transaction do
   @common_fillable_params [:chain_id, :nonce]
   @type_fillable_params %{
     legacy: [:gas_price],
-    eip1559: [:max_fee_per_gas]
+    eip1559: [:max_fee_per_gas, :max_priority_fee_per_gas]
   }
   @integer_type_values [
     :block_number,
@@ -231,6 +231,7 @@ defmodule Ethers.Transaction do
   defp fill_action(:chain_id, _tx), do: :chain_id
   defp fill_action(:nonce, tx), do: {:get_transaction_count, [tx.from, "latest"]}
   defp fill_action(:max_fee_per_gas, _tx), do: :gas_price
+  defp fill_action(:max_priority_fee_per_gas, _tx), do: :max_priority_fee_per_gas
   defp fill_action(:gas_price, _tx), do: :gas_price
 
   defp post_process([], [], acc), do: {:ok, Enum.into(acc, %{})}
@@ -251,6 +252,11 @@ defmodule Ethers.Transaction do
     end
   end
 
+  defp do_post_process(:max_priority_fee_per_gas, {:ok, v_int}) do
+    # use latest max_priority_fee_per_gas from the chain as default
+    {:ok, {:max_priority_fee_per_gas, Utils.integer_to_hex(v_int)}}
+  end
+
   defp do_post_process(key, {:ok, v_hex}) do
     {:ok, {key, v_hex}}
   end

test/ethers_test.exs

@@ -546,7 +546,25 @@ defmodule EthersTest do
         )
 
       assert signed ==
-               "0x02f8cd8205396480840756b5b38227109495ced938f7991cd0dfcb48f0a06a40fa1af46ebc80b864435ffe94000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000096869207369676e65640000000000000000000000000000000000000000000000c001a002692d6fb9c645a9c16759ad577511d132c6976eacfaeca52f564771e4b80ddea075bcae22afa255d44387ef43fc6b005cc86529c6e99364e065736804f16c1bfc"
+               "0x02f8d182053964843b9aca00840756b5b38227109495ced938f7991cd0dfcb48f0a06a40fa1af46ebc80b864435ffe94000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000096869207369676e65640000000000000000000000000000000000000000000000c001a0da576ea4a1cf5979a34056d2fde083f6567430b2286e4985ffb9ea83df69c57fa070790ded792b1e55abd3fcc13202133289dfaba0fc96b476a76f488d69b2477d"
+    end
+
+    test "returns signed transaction with custom max_priority_fee_per_gas" do
+      signed =
+        HelloWorldContract.set_hello("hi signed")
+        |> Ethers.sign_transaction!(
+          from: @from,
+          gas: 10_000,
+          max_fee_per_gas: 123_123_123,
+          max_priority_fee_per_gas: 2_000_000_000,
+          chain_id: 1337,
+          nonce: 100,
+          to: "0x95cED938F7991cd0dFcb48F0a06a40FA1aF46EBC",
+          signer: Ethers.Signer.JsonRPC
+        )
+
+      assert signed ==
+               "0x02f8d1820539648477359400840756b5b38227109495ced938f7991cd0dfcb48f0a06a40fa1af46ebc80b864435ffe94000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000096869207369676e65640000000000000000000000000000000000000000000000c001a054c7dd5c03757b3fa7c896bfb23f6bf3cf32aa21e3e53dbca00d447a673c033aa01e81b956fe27a1757f780a12570df243fc10c3a08b8647b301b1be15b376734e"
     end
 
     test "raises in case of error" do