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System test: asserting Turbo Stream responses

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                  require 'application_system_test_case'

class TasksTest < ApplicationSystemTestCase
  test 'deleting a task removes it from the list' do
    task = tasks(:one)

    visit tasks_path
    assert_selector "#task_#{task.id}"

    accept_confirm do
      click_link 'Delete', href: task_path(task)
    end

    assert_no_selector "#task_#{task.id}"
  end
end

                  <div id="<%= dom_id(task) %>">
  <%= task.title %>
</div>

I don’t test Hotwire behavior by guessing; I add system tests that exercise the UI. With Capybara, I click a button that triggers a Turbo Stream response and assert that the DOM changes without a full page reload. The exact assertion depends on the feature: a row disappears, a counter increments, a toast appears. In Rails system tests, you don’t need to parse turbo stream tags directly; you validate the user-visible result. I also like to use assert_text and assert_selector with stable ids (dom_id). This catches regressions when a template stops responding with turbo streams or when a status code changes. It’s the quickest way to keep Hotwire UX reliable.

Henry Kim

More from Henry Kim

System test: asserting Turbo Stream responses

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More from Henry Kim