System tests with Capybara in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does this Capybara test check for?

Given the following system test code, what is the expected behavior when it runs?

Ruby on Rails

require "application_system_test_case"

class PostsTest < ApplicationSystemTestCase
  test "visiting the index" do
    visit posts_url
    assert_selector "h1", text: "Posts"
  end
end

A It visits the posts index page and checks that an <h1> element with text 'Posts' is present.

B It visits the posts index page and checks that the page title is 'Posts'.

C It visits the posts show page and checks for a heading with 'Posts'.

D It visits the posts index page and checks that a link with text 'Posts' exists.

💡 Hint

Look at the visit URL and the assert_selector method.

The test visits the URL for posts index (posts_url) and asserts that an h1 element containing the text 'Posts' is present on the page.

📝 Syntax

intermediate

Identify the syntax error in this Capybara test snippet

Which option correctly fixes the syntax error in this test code?

Ruby on Rails

test "creating a post" do
  visit new_post_url
  fill_in "Title", with: "My Post"
  click_button "Create Post"
  assert_text "Post was successfully created"
end

A Wrap the test block inside a 'class PostsTest < ApplicationSystemTestCase' and add 'end' at the end.

B Add 'def test_creating_a_post' before the test block and 'end' after it.

C Add 'test' keyword before the block and ensure the block is inside a test class.

D No syntax error; the code is correct as is.

💡 Hint

System tests must be inside a test class inheriting from ApplicationSystemTestCase.

In Rails system tests, test methods must be inside a test class that inherits from ApplicationSystemTestCase. The snippet is missing the class wrapper.

❓ state_output

advanced

What is the value of 'post_count' after this test runs?

Consider this system test code snippet. What will be the value of 'post_count' after the test completes?

Ruby on Rails

test "creating a post increases count" do
  post_count = Post.count
  visit new_post_url
  fill_in "Title", with: "New Post"
  click_button "Create Post"
  assert_text "Post was successfully created"
  post_count = Post.count
end

A post_count will be nil because it is not returned from the test.

B post_count will be the original count because system tests run in a transaction rollback.

C post_count will be zero because the database is reset before each test.

D post_count will be original count + 1 because a new post was created.

💡 Hint

Think about when the count is checked and if the post creation was successful.

The test checks the post count before and after creating a post. After clicking 'Create Post', the post is saved, so the count increases by 1.

🔧 Debug

advanced

Why does this Capybara test fail with a 'Capybara::ElementNotFound' error?

Given this test code, why does it raise 'Capybara::ElementNotFound'?

Ruby on Rails

test "deleting a post" do
  visit posts_url
  click_on "Delete", match: :first
  assert_text "Post was successfully destroyed"
end

A The test does not wait for the page to load before clicking 'Delete'.

B The 'click_on' method requires an exact match and 'match: :first' is invalid.

C There is no 'Delete' link or button on the posts index page.

D The 'assert_text' is called before the deletion completes.

💡 Hint

Check if the page actually has a 'Delete' link or button visible.

The error means Capybara cannot find any element with text 'Delete'. This usually happens if the link or button is missing or named differently.

🧠 Conceptual

expert

Which statement about Capybara's 'visit' method in system tests is true?

Select the correct statement about how Capybara's 'visit' method works in Rails system tests.

A 'visit' only works with local file paths, not URLs.

B 'visit' opens the URL in a real browser controlled by Capybara's driver during the test run.

C 'visit' simulates a server-side redirect without opening a browser window.

D 'visit' immediately executes JavaScript on the page before loading.

💡 Hint

Think about how Capybara interacts with the browser during system tests.

Capybara's 'visit' method opens the given URL in a browser controlled by the test driver (like Selenium). This simulates a real user visiting the page.