MastoAPI: Add GET /api/v1/accounts/lookup

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

test/pleroma/web/mastodon_api/controllers/account_controller_test.exs

@@ -1776,4 +1776,28 @@ defmodule Pleroma.Web.MastodonAPI.AccountControllerTest do
 
     assert [%{"id" => ^id2}] = result
   end
+
+  test "account lookup", %{conn: conn} do
+    %{nickname: acct} = insert(:user, %{nickname: "nickname"})
+    %{nickname: acct_two} = insert(:user, %{nickname: "nickname@notlocaldoma.in"})
+
+    result =
+      conn
+      |> get("/api/v1/accounts/lookup?acct=#{acct}")
+      |> json_response_and_validate_schema(200)
+
+    assert %{"acct" => ^acct} = result
+
+    result =
+      conn
+      |> get("/api/v1/accounts/lookup?acct=#{acct_two}")
+      |> json_response_and_validate_schema(200)
+
+    assert %{"acct" => ^acct_two} = result
+
+    _result =
+      conn
+      |> get("/api/v1/accounts/lookup?acct=unexisting_nickname")
+      |> json_response_and_validate_schema(404)
+  end
 end