Add parser function to handle addresses arguments when calling the blockchain

apps/ethereum_jsonrpc/lib/ethereum_jsonrpc/encoder.ex

@@ -45,12 +45,23 @@ defmodule EthereumJSONRPC.Encoder do
   def encode_function_call({function_selector, args}) do
     encoded_args =
       function_selector
-      |> ABI.encode(args)
+      |> ABI.encode(parse_args(args))
       |> Base.encode16(case: :lower)
 
     {function_selector.function, "0x" <> encoded_args}
   end
 
+  defp parse_args(args) do
+    args
+    |> Enum.map(fn
+      <<"0x", hexadecimal_digits::binary>> ->
+        Base.decode16!(hexadecimal_digits, case: :mixed)
+
+      item ->
+        item
+    end)
+  end
+
   @doc """
   Given a result set from the blockchain, and the functions selectors, returns the results decoded.
 

apps/ethereum_jsonrpc/test/ethereum_jsonrpc/encoder_test.exs

@@ -26,6 +26,20 @@ defmodule EthereumJSONRPC.EncoderTest do
       assert Encoder.encode_function_call({function_selector, [10]}) ==
                {"get", "0x9507d39a000000000000000000000000000000000000000000000000000000000000000a"}
     end
+
+    test "generates the correct encoding with addresses arguments" do
+      function_selector = %ABI.FunctionSelector{
+        function: "tokens",
+        returns: {:uint, 256},
+        types: [:address, :address]
+      }
+
+      args = ["0xdab1c67232f92b7707f49c08047b96a4db7a9fc6", "0x6937cb25eb54bc013b9c13c47ab38eb63edd1493"]
+
+      assert Encoder.encode_function_call({function_selector, args}) ==
+               {"tokens",
+                "0x508493bc000000000000000000000000dab1c67232f92b7707f49c08047b96a4db7a9fc60000000000000000000000006937cb25eb54bc013b9c13c47ab38eb63edd1493"}
+    end
   end
 
   describe "get_selectors/2" do