Add function to fetch users from fqn.

lib/pleroma/user.ex

@@ -3,6 +3,7 @@ defmodule Pleroma.User do
   import Ecto.Changeset
   import Ecto.Query
   alias Pleroma.{Repo, User, Activity, Object}
+  alias Pleroma.Web.OStatus
 
   schema "users" do
     field :bio, :string
@@ -131,4 +132,15 @@ def get_cached_user_info(user) do
     key = "user_info:#{user.id}"
     Cachex.get!(:user_cache, key, fallback: fn(_) -> user_info(user) end)
   end
+
+  def get_or_fetch_by_nickname(nickname) do
+    with %User{} = user <- get_by_nickname(nickname)  do
+      user
+    else _e ->
+      with {:ok, user} <- OStatus.make_user(nickname) do
+        user
+      else _e -> nil
+      end
+    end
+  end
 end

test/user_test.exs

@@ -86,4 +86,24 @@ test "it sets the password_hash, ap_id and following fields" do
       assert changeset.changes[:following] == [User.ap_followers(%User{nickname: @full_user_data.nickname})]
     end
   end
+
+  describe "fetching a user from nickname or trying to build one" do
+    test "gets an existing user" do
+      user = insert(:user)
+      fetched_user = User.get_or_fetch_by_nickname(user.nickname)
+
+      assert user == fetched_user
+    end
+
+    test "fetches an external user via ostatus if no user exists" do
+      fetched_user = User.get_or_fetch_by_nickname("shp@social.heldscal.la")
+      assert fetched_user.nickname == "shp@social.heldscal.la"
+    end
+
+    test "returns nil if no user could be fetched" do
+      fetched_user = User.get_or_fetch_by_nickname("nonexistant@social.heldscal.la")
+      assert fetched_user == nil
+    end
+  end
 end
+