Regex in capybara have_xpath - regex

Question

I have a text changing decoration when it is clicked. In my tests before clicking I want to check whether it's already clicked or not. It changes color, text decoration and href which I want to check through.
As href contains session specific information, so I want to use regex.
if page.have_xpath("//a[contains(#href,\"%20Administrators?\")]")
This passes even the page has already been updated and Administrators text has changed to something else.
How should I correct the syntax to accept all href containing "%20Administrators?" text. I want add it to if clause as if the page has the link with text Administrators in it.
Before clicking: href="/sometext/%20Administrators?redirect=sometext"
After clicking : href="/sometext/%20Standard?redirect=sometext"

Answer 1

The primary issue you're having here is using have_xpath rather than has_xpath?. have_xpath returns an RSpec matcher, and as such when used with if will always evaluate as true (since it returns an object and hasn't yet actually evaluated any XPath passed in). has_xpath? returns a boolean result of true or false.
if page.has_xpath?('.//a[contains(#href,"%20Administrators?")]')
The second issue is that your question asks about regex, but XPath 1.0 (which browsers support) doesn't have regex support and your XPath isn't using regex at all (just a contains expression). If you actually want to use regex for testing the href (and have better reading code) you should be using the has_link? boolean method - along the lines of
if page.has_link?(href: /Administrators/)
has_link? can also verify the visible text of the link too if wanted
if page.has_link?('Visible text of the link', href: /Administrators/)
Finally, when using XPath with Capybara, 99% of the time you should start your XPath with .// instead of just // - see https://github.com/teamcapybara/capybara#beware-the-xpath--trap - and is one reason why it's usually cleaner to use CSS and/or the more specific methods provided by Capybara rather than the xxx_xpath methods.
One other thing to note is that all of the methods mentioned have waiting behavior by default, so they will wait up to Capybara.default_max_wait_time seconds for the page to have a matching link. If you know the page is stable and just want to immediately know whether or not a matching link exists you might want to pass wait: false as an option
if page.has_link?(href: /Administrators/, wait: false)