Add regression tests

apps/explorer/lib/explorer/smart_contract/reader.ex

@@ -295,7 +295,7 @@ defmodule Explorer.SmartContract.Reader do
     end
   end
 
-  defp get_abi_with_method_id(abi) do
+  def get_abi_with_method_id(abi) do
     abi
     |> Enum.map(fn method ->
       with parsed_method <- [method] |> ABI.parse_specification() |> Enum.at(0),

apps/explorer/test/explorer/smart_contract/reader_test.exs

@@ -366,6 +366,41 @@ defmodule Explorer.SmartContract.ReaderTest do
     end
   end
 
+  describe "get_abi_with_method_id" do
+    test "add method_id to the ABI method" do
+      method = %{
+        "constant" => true,
+        "inputs" => [%{"name" => "_message", "type" => "bytes32"}],
+        "name" => "numMessagesSigned",
+        "outputs" => [%{"name" => "", "type" => "uint256"}],
+        "payable" => false,
+        "stateMutability" => "view",
+        "type" => "function"
+      }
+
+      abi = [method]
+      method_with_id = Map.put(method, "method_id", "0cbf0601")
+      assert [method_with_id] = Reader.get_abi_with_method_id(abi)
+    end
+
+    test "do not crash in some corner cases" do
+      abi = [
+        %{"payable" => true, "stateMutability" => "payable", "type" => "fallback"},
+        %{
+          "anonymous" => false,
+          "inputs" => [
+            %{"indexed" => false, "name" => "recipient", "type" => "address"},
+            %{"indexed" => false, "name" => "value", "type" => "uint256"}
+          ],
+          "name" => "UserRequestForSignature",
+          "type" => "event"
+        }
+      ]
+
+      assert abi = Reader.get_abi_with_method_id(abi)
+    end
+  end
+
   defp blockchain_get_function_mock do
     expect(
       EthereumJSONRPC.Mox,