tests: add tests for MRF.describe()

test/support/mrf_module_mock.ex

@@ -9,5 +9,5 @@ defmodule MRFModuleMock do
   def filter(message), do: {:ok, message}
 
   @impl true
-  def describe(), do: %{"mrf_module_mock" => "some config data"}
+  def describe(), do: {:ok, %{mrf_module_mock: "some config data"}}
 end

test/web/activity_pub/mrf/mrf_test.exs

@@ -57,4 +57,30 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
       refute MRF.subdomain_match?(regexes, "example.com")
     end
   end
+
+  describe "describe/0" do
+    test "it works as expected with noop policy" do
+      expected = %{
+        mrf_policies: ["NoOpPolicy"],
+        exclusions: false
+      }
+
+      {:ok, ^expected} = MRF.describe()
+    end
+
+    test "it works as expected with mock policy" do
+      config = Pleroma.Config.get([:instance, :rewrite_policy])
+      Pleroma.Config.put([:instance, :rewrite_policy], [MRFModuleMock])
+
+      expected = %{
+        mrf_policies: ["MRFModuleMock"],
+        mrf_module_mock: "some config data",
+        exclusions: false
+      }
+
+      {:ok, ^expected} = MRF.describe()
+
+      Pleroma.Config.put([:instance, :rewrite_policy], config)
+    end
+  end
 end