Fix format validation bug

Author: undr

lib/jsonrpc2_plug/validator.ex

@@ -54,7 +54,7 @@ defmodule JSONRPC2Plug.Validator do
       if is_nil(value) || (is_binary(value) && Regex.match?(regex, value)) do
         :ok
       else
-        {:error, "does not match format %{format}", [format: regex]}
+        {:error, "does not match format %{format}", [format: Regex.source(regex)]}
       end
     end
   end

test/jsonrpc2_plug/validator_test.exs

@@ -25,8 +25,8 @@ defmodule JSONRPC2Plug.ValidatorTest do
   end
 
   test ".format" do
-    assert {:error, "does not match format %{format}", [format: ~r/some/]} = Validator.format(~r/some/).("xxx")
-    assert {:error, "does not match format %{format}", [format: ~r/some/]} = Validator.format(~r/some/).(123)
+    assert {:error, "does not match format %{format}", [format: "some"]} = Validator.format(~r/some/).("xxx")
+    assert {:error, "does not match format %{format}", [format: "some"]} = Validator.format(~r/some/).(123)
     assert :ok = Validator.format(~r/some/).(nil)
     assert :ok = Validator.format(~r/some/).("something")
   end