Merge branch 'bugfix/mrf-antifollowbot-nil-bio' into 'develop'

MRF: anti followbot: gracefully handle nil display names

See merge request pleroma/pleroma!909

lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex

@@ -23,15 +23,21 @@ defp score_displayname("fedibot"), do: 1.0
   defp score_displayname(_), do: 0.0
 
   defp determine_if_followbot(%User{nickname: nickname, name: displayname}) do
+    # nickname will always be a binary string because it's generated by Pleroma.
     nick_score =
       nickname
       |> String.downcase()
       |> score_nickname()
 
+    # displayname will either be a binary string or nil, if a displayname isn't set.
     name_score =
-      displayname
-      |> String.downcase()
-      |> score_displayname()
+      if is_binary(displayname) do
+        displayname
+        |> String.downcase()
+        |> score_displayname()
+      else
+        0.0
+      end
 
     nick_score + name_score
   end

test/web/activity_pub/mrf/anti_followbot_policy_test.exs

@@ -54,4 +54,19 @@ test "it allows non-followbots" do
 
     {:ok, _} = AntiFollowbotPolicy.filter(message)
   end
+
+  test "it gracefully handles nil display names" do
+    actor = insert(:user, %{name: nil})
+    target = insert(:user)
+
+    message = %{
+      "@context" => "https://www.w3.org/ns/activitystreams",
+      "type" => "Follow",
+      "actor" => actor.ap_id,
+      "object" => target.ap_id,
+      "id" => "https://example.com/activities/1234"
+    }
+
+    {:ok, _} = AntiFollowbotPolicy.filter(message)
+  end
 end