Set last_login_at only at login instead of every single action (#1017)

test/controllers/sessions_controller_test.rb

@@ -0,0 +1,18 @@
+require "test_helper"
+
+class SessionsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    @user = users(:family_admin)
+  end
+
+  test "can sign in" do
+    post session_url, params: { email: @user.email, password: "password" }
+    assert_redirected_to root_url
+  end
+
+  test "sets last_login_at on successful login" do
+    assert_changes -> { @user.reload.last_login_at }, from: nil do
+      post session_url, params: { email: @user.email, password: "password" }
+    end
+  end
+end