Why doesn't my instance variable point to a Watir::Browser instance?
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27-06-2021 - |
Pergunta
I'm really confused about this. I'm using the Ruby class below in an automated test suite:
class FlightSearchPage
attr_accessor :page_title
def initialize(browser, page)
@browser = browser
@start_url = page
end
def method_missing(sym, *args, &block)
@browser.send sym, *args, &block
end
@page_title = @browser.title
#def page_title
# @browser.title
#end
end
I'm subclassing it with:
class BrandFlightsPage < FlightSearchPage
def initialize(browser, page, brand)
super(browser, page)
[...snip...]
end
end
When I instantiate the subclass, passing in @browser, a watir-webdriver object, @browser.title throws:
undefined method `title' for nil:NilClass (NoMethodError)
But if I uncomment the page_title method in FlightSearchPage, it works as expected. I've also tried it with the variable assignment inside the constructor.
I've gone around in circles trying to track this down, but I just can't see it.
Here's the stacktrace:
undefined method `title' for nil:NilClass (NoMethodError)
/Users/Dazzla/Dropbox/src/Projects/over_the_watir/pages/flight_search_page.rb:13:in `<class:FlightSearchPage>'
/Users/Dazzla/Dropbox/src/Projects/over_the_watir/pages/flight_search_page.rb:1:in `<top (required)>'
/usr/local/rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in `require'
/usr/local/rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in `require'
/Users/Dazzla/Dropbox/src/Projects/over_the_watir/pages/brand_flight_search_page.rb:1:in `<top (required)>'
/usr/local/rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in `require'
/usr/local/rvm/rubies/ruby-1.9.3-p0/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:55:in `require'
/Users/Dazzla/Dropbox/src/Projects/over_the_watir/features/step_definitions/steps.rb:1:in `<top (required)>'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/rb_support/rb_language.rb:129:in `load'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/rb_support/rb_language.rb:129:in `load_code_file'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime/support_code.rb:171:in `load_file'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime/support_code.rb:83:in `block in load_files!'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime/support_code.rb:82:in `each'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime/support_code.rb:82:in `load_files!'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime.rb:175:in `load_step_definitions'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/runtime.rb:40:in `run!'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/cli/main.rb:43:in `execute!'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/lib/cucumber/cli/main.rb:20:in `execute'
/usr/local/rvm/gems/ruby-1.9.3-p0/gems/cucumber-1.2.1/bin/cucumber:14:in `<top (required)>'
/usr/local/rvm/gems/ruby-1.9.3-p0/bin/cucumber:19:in `load'
/usr/local/rvm/gems/ruby-1.9.3-p0/bin/cucumber:19:in `<main>'
Solução
This is because
attr_accessor :page_title
already creates a getter and a setter.
i would put this
@page_title = @browser.title
inside your initialize method..
class FlightSearchPage
attr_accessor :page_title
def initialize(browser, page)
@browser = browser
@page_title = @browser.title
@start_url = page
end
def method_missing(sym, *args, &block)
@browser.send sym, *args, &block
end
end
or (better) remove the attr_accessor and just add a method
class FlightSearchPage
def initialize(browser, page)
@browser = browser
@start_url = page
end
def method_missing(sym, *args, &block)
@browser.send sym, *args, &block
end
def page_title
return @browser.title unless @browser
"browser not set, no title"
end
end
Instantiating the browser:
This is placed in a file called env.rb which is run before each test:
Before do
@browser = Watir::Browser.new
end
It's run in the context of the current instance of cucumber's World
What I don't understand is that all other browser methods are working as expected when implemented with accessors except this one.