Capybara Ambiguity Resolution

问题:

How do I resolve ambiguity in Capybara? For some reason I need links with the same values in a page but I can't create a test since I get the error

Failure/Error: click_link("#tag1")
     Capybara::Ambiguous:
       Ambiguous match, found 2 elements matching link "#tag1"

The reason why I can't avoid this is because of the design. I'm trying to recreate the twitter page with tweets/tags on the right and the tags on the left of the page. Therefore it will be inevitable that identical links page shows up on the same page.

回答1:

My solution is

first(:link, link).click

instead of

click_link(link)

回答2:

Such behavior of Capybara is intentional and I believe it shouldn't be fixed as suggested in most of other answers.

Versions of Capybara before 2.0 returned the first element instead of raising exception but later maintainers of Capybara decided that it's a bad idea and it's better to raise it. It was decided that in many situations returning first element leads to returning not the element that the developer wanted to be returned.

The most upvoted answer here recommend to use first or all instead of find but:

1. all and first don't wait till element with such locator will appear on the page though find does wait
2. all(...).first and first won't protect you from situation that in future another element with such locator may appear on the page and as the result you may find incorrect element

So it's adviced to choose another, less ambiguous locator: for example select element by id, class or other css/xpath locator so that only one element will match it.

---

As a note here are some locators that I usually consider useful when resolving ambiguity:

• find('ul > li:first-child')

  It's more useful than first('ul > li') as it will wait till first li will appear on the page.

• click_link('Create Account', match: :first)

  It's better than first(:link, 'Create Account').click as it will wait till at least one Create Account link will appear on the page. However I believe it's better to choose unique locator that doesn't appear on the page twice.

• fill_in('Password', with: 'secret', exact: true)

  exact: true tells Capybara to find only exact matches, i.e. not find "Password Confirmation"

回答3:

The above solution works great but for those curious you can also use the following syntax.

click_link(link_name, match: :first)

You can find more information here:

http://taimoorchangaizpucitian.wordpress.com/2013/09/06/capybara-click-link-different-cases-and-solutions/

回答4:

NEW ANSWER:

You can try something like

all('a').select {|elt| elt.text == "#tag1" }.first.click

There may be a way to do this which makes better use of the available Capybara syntax -- something along the lines of all("a[text='#tag1']").first.click but I can't think of the correct syntax off hand and I can't find the appropriate documentation. That said it's a bit of a strange situation to begin with, having two <a> tags with the same id, class, and text. Is there any chance they are children of different divs, since you could then do your find within the appropriate segment of the DOM. (It would help to see a bit of your HTML source).

---

OLD ANSWER: (where I thought '#tag1' meant the element had an id of "tag1")

Which of the links do you want to click on? If it's the first (or it doesn't matter), you can do

find('#tag1').click

Otherwise you can do

all('#tag1')[1].click

to click the second one.

回答5:

You can ensure that you find the first one using match:

find('.selector', match: :first).click

But importantly, you probably do not want to do this, as it will lead to brittle tests that are ignoring the duplicate-output code smell, which in turn leads to false positives that keep working when they should have failed, because you removed one matching element but the test happily found the other one.

The better bet is to use within:

within('#sidebar') do
  find('.selector).click
end

This ensures that you're finding the element you expect to find, while still leveraging the auto-wait and auto-retry capabilities of Capybara (which you lose if you use find('.selector').click), and it makes it much clearer what the intent is.

回答6:

To add to the existing body of knowledge here:

For JS tests, Capybara has to keep two threads (one for RSpec, one for Rails) and a second process (the browser) in sync. It does this by waiting (up to the configured maximum wait time) in most matchers and node-finding methods.

Capybara also has methods that don't wait, primarily Node#all. Using them is like telling your specs that you'd like them to fail intermittently.

The accepted answer suggests page.first('selector'). This is undesirable, at least for JS specs, because Node#first uses Node#all.

That said, Node#first will wait if you configure Capybara like so:

# rails_helper.rb
Capybara.wait_on_first_by_default = true

This option was added in Capybara 2.5.0 and is false by default.

As Andrei mentioned, you should instead use

find('selector', match: :first)

or change your selector. Either will work well regardless of config or driver.

To further complicate things, in old versions of Capybara (or with a config option enabled), #find will happily ignore ambiguity and just return the first matching selector. This isn't great either, as it makes your specs less explicit, which I imagine is why no longer the default behavior. I'll leave out the specifics because they've been discussed above already.

More resources:

• https://robots.thoughtbot.com/write-reliable-asynchronous-integration-tests-with-capybara
• http://makandracards.com/makandra/20829-threads-and-processes-in-a-capybara-selenium-session

回答7:

Due to this post, you can fix it via "match" option:

Capybara.configure do |config|
  config.match = :prefer_exact
end

回答8:

To avoid ambiguous error in cucumber.

Solution 1

first("#tag1").click

Solution 2

Cucumber features/filename.feature --guess