Fix false positive on UnusedFunctionReturnHelper

lib/credo/check/warning/unused_function_return_helper.ex

@@ -194,6 +194,22 @@ defmodule Credo.Check.Warning.UnusedFunctionReturnHelper do
     end
   end
 
+  # module.my_fun()
+  defp verify_candidate(
+         {{:., _, [{module, _, []}, fun_name]}, _, arguments} = ast,
+         :not_verified = acc,
+         candidate
+       )
+       when is_atom(fun_name) and is_atom(module) and is_list(arguments) do
+    # IO.inspect(ast, label: "Mod.fun() (#{Macro.to_string(candidate)} #{acc})")
+
+    if CodeHelper.contains_child?(arguments, candidate) do
+      {nil, :VERIFIED}
+    else
+      {ast, acc}
+    end
+  end
+
   # MyModule.my_fun()
   defp verify_candidate(
          {{:., _, [{:__aliases__, _, mods}, fun_name]}, _, arguments} = ast,

test/credo/check/warning/unused_path_operation_test.exs

@@ -10,6 +10,32 @@ defmodule Credo.Check.Warning.UnusedPathOperationTest do
         Path.join(parameter1) + parameter2
       end
     end
+
+    defmodule CredoExample do
+      def error do
+        module().call(Path.join("~", "foo"))
+
+        "something"
+      end
+
+      def no_error(:one) do
+        call(Path.join("~", "foo"))
+
+        "something"
+      end
+
+      def no_error(:two) do
+        module().call(Path.join("~", "foo"))
+      end
+
+      defp call(path) do
+        IO.puts path
+      end
+
+      defp module do
+        CredoExample
+      end
+    end
     """
     |> to_source_file
     |> refute_issues(@described_check)