add user model

spec/models/user_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: users
+#
+#  id         :bigint           not null, primary key
+#  email      :string           not null
+#  first_name :string           not null
+#  last_name  :string           not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+# Indexes
+#
+#  index_users_on_email  (email) UNIQUE
+#
+require "rails_helper"
+
+RSpec.describe(User, type: :model) do
+  describe "validations" do
+    it { is_expected.to(validate_presence_of(:first_name)) }
+    it { is_expected.to(validate_presence_of(:last_name)) }
+    it { is_expected.to(validate_presence_of(:email)) }
+  end
+end