Add test for warnings if referencing filtered typespec

Closes #1764

Author: wojtekmach

lib/ex_doc/language/elixir.ex

@@ -670,7 +670,7 @@ defmodule ExDoc.Language.Elixir do
       original_text = call_string <> "()"
 
       if Enum.any?(config.filtered_modules, &(&1.id == module_string)) do
-        Autolink.warn(config, "Typespec references filtered module: #{all}")
+        Autolink.warn(config, "typespec references filtered module: #{all}")
       end
 
       url =

test/ex_doc/language/elixir_test.exs

@@ -470,16 +470,6 @@ defmodule ExDoc.Language.ElixirTest do
              ~s|<code class="inline">t:InMemory.unknown/0</code>|
   end
 
-  test "warning if typespec references filtered module" do
-    ExDoc.Refs.insert([
-      {{:module, AutolinkTest.Keep}, :public},
-      {{:function, AutolinkTest.Filtered}, :public},
-      {{:type, AutolinkTest.Filtered, :type, 0}, :public}
-    ])
-
-    # TODO: testing
-  end
-
   test "warnings" do
     ExDoc.Refs.insert([
       {{:module, AutolinkTest.Foo}, :public},
@@ -578,6 +568,11 @@ defmodule ExDoc.Language.ElixirTest do
              autolink_spec(quote(do: t() :: String.bad()), opts)
            end) =~ ~s|documentation references type "String.bad()"|
 
+    assert warn(fn ->
+             opts = opts ++ [filtered_modules: [%ExDoc.ModuleNode{id: "String"}]]
+             autolink_spec(quote(do: t() :: String.t()), opts)
+           end) == "typespec references filtered module: String.t()"
+
     assert warn(fn ->
              autolink_spec(
                quote do