Lucky Logo

# About Flow

LuckyFlow is a shard that allows you to programmatically control a browser. This is best used to test your front-end and how users directly interact with your website in a browser.

The name “flow” comes from the idea that a user will follow a “flow” from some starting point to some ending point. (e.g. Clicking login, entering login details, and being redirected to a dashboard)

LuckyFlow is automatically installed and configured with Lucky full (or web) projects. API based projects don’t need it since there’s no HTML, CSS, or JavaScript.

# Setup

LuckyFlow uses chromedriver to control Selenium under the hood. You don’t need anything installed as LuckyFlow will automatically install the chromedriver for you when it runs the first time.

The LuckyFlow configuration settings are located in spec/setup/

# spec/setup/
LuckyFlow.configure do |settings|
  settings.stop_retrying_after = 200.milliseconds
  settings.base_uri = Lucky::RouteHelper.settings.base_uri
  settings.retry_delay = 10.milliseconds

  # Change where screenshots are stored
  settings.screenshot_directory = "./tmp/screenshots"

  # Point to a different Chrome browser than the default
  settings.browser_binary = "/Applications/Google Chrome"

  # Specify a custom location to the driver
  settings.driver_path = "/path/to/driver"

  # Change which driver is loaded. (`LuckyFlow::Drivers::HeadlessChrome` is default)
  settings.driver = LuckyFlow::Drivers::Chrome

# A quick overview of flows

LuckyFlow provides methods for visiting pages, clicking and interacting with elements, and filling forms.

# Create a Flow spec in spec/flows/

When writing flow specs, it’s best to write the spec as a full flow that a user might take. For example, here is a flow for publishing an article:

# spec/flows/
describe "Publish post flow" do
  it "works successfully" do
    flow =


# Create a Flow object

Then create a Flow object that performs the interactions and assertions:

# spec/support/flows/
class PublishPostFlow < BaseFlow
  def start_draft
    visit Articles::Index
    click "@new-post"

  def create_draft
    fill_form SaveArticle,
      title: "Draft Post",
      body: "body"
    click "@save-draft"

  def draft_should_be_created
    draft_title.should be_on_page

  def open_draft

  private def draft_title

  def publish_post
    fill_form PublishArticle,
      title: "Published Post"
    click "@publish-post"

  def post_should_be_published
    el("@post-title", text: "Published Post").should be_on_page

# Visiting pages

You can visit pages with some built-in methods that accepts strings and Lucky routes.

# Using with Lucky actions

# Visit an action that does not need params
visit Home::Index

# Visit a route that takes params
post = PostFactory.create
visit Posts::Show.with(

# Using as to sign users in

Lucky comes built-in with a backdoor in tests so that you don’t need to go through the full process of loading the sign in page and filling out the form. Instead you can use the as option to visit the page and sign the user in automatically:

user = UserFactory.create
post = PostFactory.create
visit Posts::Show.with(, as: user

Check out the Auth::SignInThroughBackdoor mixin to see how the backdoor works.

# Using strings paths

You should generally use Lucky routes but if you need to you can use strings to visit a path

visit "/posts"

# Finding elements

You can work with elements using the el method.

Note that finding elements with el is lazy. That means that when you call el it will not fail if it can’t find an element, because it won’t try to find the element until you try to interact with it or check if it is in the page.

# Using @ to find by Flow ID

If you are familiar with other libraries for interacting with pages, you likely have found elements using CSS or by the text inside of elements. This can be brittle because CSS and text can change and then break your tests even though the feature still works.

Instead of using CSS or text, you can use the special @ selector for interacting with elements. This uses an HTML attribute called flow-id:

# Looks for an element with an HTML attribute called "flow-id"
# with the value "view-posts"

Using this in a Lucky page is simple:

# LuckyFlow will find this element
link "View Posts", Posts::Index, flow_id: "view-posts"

# Finding with CSS

You can also find elements by CSS, but using Flow IDs is preferred because your tests will be more resilient to change.

In the cases when you do need to use CSS, here’s how you would do it:

# look for an anchor tag with the "post-title" class
# look for an element with an id of "post-button"

# Finding elements that contain text

Sometimes you want to only find elements that contain certain text. Use the text option:

el("", text: "Title of post")
el("@post-title", text: "Title of post")

# Interacting with elements

# Clicking an element

el("", text: "My title").click
# Or use the shortcut method `click`
click "@save-button"
click ""

# Hover over an element


# Checking visiblity of an element

.alert-box { display: none; }
.upload-zone:hover + .alert-box { display: block; }
<div class="upload-zone" flow-id="file-upload-box">Drop Files Here</div>
<div class="alert-box">Ready for upload!</div>
el(".alert-box").displayed? #=> false


el(".alert-box").displayed? #=> true

# Filling and submitting forms

Fill forms rendered by Lucky:

fill_form SavePost,
  title: "My Post",
  body: "Post body"

You can also fill forms based on the input’s name:

fill "post:title", with: "My Post"

Or use the fill method on an element:

el("#title-field").fill("My Post")

# Filling select fields

To fill the value of a <select> tag, use the method.

<select name="cars" flow_id="car-list">
  <option value="ford">Ford</option>
  <option value="honda">Honda</option>
  <option value="tesla">Tesla</option>
</select>"cars", value: "honda")
flow.el("@car-list").value.should eq "honda"

If you need to fill multiple values for a <select multiple> tag, you can pass an array."cars", value: ["honda", "toyota"])

Check if a specific value is selected using the selected? method.

flow.el("option[value='tesla']").selected? #=> false
flow.el("option[value='toyota']").selected? #=> true

# Interacting with JavaScript

# Dismissing alerts

If your page as a confirm() modal, you can accept or dismiss with the accept_alert or dismiss_alert methods."@delete-comment-button")

For javascript alert() modals, the accept_alert and dismiss_alert do the same thing.

# Spec Assertions

LuckyFlow comes with a few methods for asserting elements exist

# Asserting elements are on the page

You can use el combined with the be_on_page matcher to assert that an element is on the page:

el("@post-title", text: "My post").should be_on_page

# Asserting the current URL path

You can use have_current_path to check that the page you are on matches the path you expect

flow =
flow.visit Authenticated::Endpoint::Index
flow.should have_current_path(SignIn::New)

# Asserting an element’s text

The have_text will test that an element contains a piece of text.

<ul flow_id="user-list">
el("@user-list").should have_text("Tony")

# Managing Cookies

You can access cookies using the flow’s session.cookie_manager.

flow =

flow.visit SomePage::Index

flow.session.cookie_manager.add_cookie("hello", "world")
flow.session.cookie_manager.get_cookie("hello") #=> "world"

# Debugging

For debugging tips with LuckyFlow, read our Debugging Tests guide.

See a problem? Have an idea for improvement? Edit this page on GitHub