add users from csv util

services/app/apps/codebattle/lib/codebattle/utils/populate_users.ex

@@ -0,0 +1,24 @@
+defmodule Codebattle.Utils.PopulateUsers do
+  @moduledoc false
+
+  def from_csv(file) do
+    utc_now = NaiveDateTime.utc_now() |> NaiveDateTime.truncate(:second)
+
+    users =
+      File.stream!(file)
+      |> NimbleCSV.RFC4180.parse_stream()
+      |> Stream.map(&row_to_user(&1, utc_now))
+      |> Enum.to_list()
+
+    Codebattle.Repo.insert_all(Codebattle.User, users)
+  end
+
+  defp row_to_user([name, password], now) do
+    %{
+      name: name,
+      password_hash: Bcrypt.hash_pwd_salt(password),
+      inserted_at: now,
+      updated_at: now
+    }
+  end
+end

services/app/apps/codebattle/test/codebattle/utils/populate_users_test.exs

@@ -0,0 +1,20 @@
+defmodule Codebattle.Utils.PopulateUsersTest do
+  use Codebattle.DataCase, async: true
+
+  test "from_csv" do
+    csv = """
+    name,password
+    user1,p@ssw0rd!
+    user2,adminadmin1234
+    user3,changem3
+    user4,"hop hey lala ley"
+    """
+
+    {fd, path} = Temp.open!()
+    IO.write(fd, csv)
+    File.close(fd)
+
+    assert {4, nil} = Codebattle.Utils.PopulateUsers.from_csv(path)
+    assert %{name: "user1"} = Codebattle.User.authenticate("user1", "p@ssw0rd!")
+  end
+end