#291 Testing with VCR pro

Oct 17, 2011 | 13 minutes | Testing, Plugins

If you ever need to test an application which communicates with an external API, VCR is the way to go. Here I show a workflow in RSpec, how to use with capybara-mechanize, how to add sanitization filtering, and more.

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Radha almost 13 years ago

I was using VCR and come into a particular problem, i do no communicate to the web service directly i first establish a reverse ssh tunnel to another computer in the network, so i could not figure a way to capture the request. Any suggestions?

Ryan Bates almost 13 years ago

Since VCR only stubs HTTP requests it won't work over an SSH tunnel. However what you can do is setup a proxy server that is before the SSH tunnel and have VCR record requests that go to that server. I haven't actually tried this, and it's a bit advanced, but hopefully it will give you some ideas.

Max Gonzih almost 13 years ago

Can i use vcr with capybara + selenium?

Awesome episode. I add capybara-mechanize for OAuth testing in my app.

Ryan Bates almost 13 years ago

I don't think so, but I haven't tried it. VCR needs to stub out the HTTP request, so that needs to happen in Ruby. I don't think the Capybara Selenium driver uses Ruby at all to perform the HTTP requests. It instead communicates with Selenium at a higher level. I believe the same goes for Capybara Webkit and other alternatives.

That said, what you can do is setup a proxy Rack server which all remote requests go through. This can forward all HTTP requests to their remote destination using Net::HTTP and therefore use VCR to record it. It would look like this: Capybara > Selenium > Rack proxy server > Remote server.

Myron Marston almost 13 years ago

Can i use vcr with capybara + selenium?

To add to what Ryan said...it depends on what you mean. If you want to use VCR to record/replay HTTP requests made by your rack application, and you are using capybara + selenium to do full-stack integration testing--then yes. VCR isn't coupled to a particular capybara driver (or any testing library, really) so it should work fine, as long as you are making HTTP requests with one of the supported HTTP client libraries.

If you are wanting to use capybara + selenium to test-drive an external website like what Ryan demonstrated with capybara-mechanize...then I'm not sure. I wasn't aware capybara-mechanize allowed you to do that.

Basically, VCR will work with anything as long as you are using one of the supported HTTP client libraries (or a library built on top of one of those--like how rest-client is built on top of Net::HTTP), you have control of the ruby process where the HTTP requests are being made, and you have a way to wrap the code making the HTTP requests in a VCR.use_cassette call.

Max Gonzih almost 13 years ago

Thanks for answer!

debprado almost 13 years ago

I haven't been able to use VCR in tests with :js => true (capybara + selenium)

The first time I run the test it passes and the cassette is recorded.

However, when I use the cassette, the test fails with Unregistered request:

POST http://127.0.0.1:7055/hub/session/..... with body '{"url":"http://subdomain.myapp.com/settings"}'

The url is different every time.

I'm using nginx locally so I can use ssl, *.myapp.com is going to 127.0.0.1:3000, I've set Capybara server_port to on 3000 and Capybara.app_host = "subdomain.myapp.com". Is that what's messing things up?

debprado almost 13 years ago

to answer my own question :):

https://www.relishapp.com/myronmarston/vcr/v/1-6-0/docs/configuration/ignore-hosts

Michel Pouleijn almost 13 years ago

I'm having a challenge with VCR and I hope someone can help me with that.

I have a planning API I wanted to connect to and i want to validate the data from the api with my models.

In my system an Employee has an association with with an address. To get a valid employee i need to do two requests to the API.
1. To get the employee
2. To get the address of the employee.

But VCR doesn't allow me to record 2 API calls in one function. Any idea how to handle this?

Myron Marston almost 13 years ago

But VCR doesn't allow me to record 2 API calls in one function. Any idea how to handle this?

VCR is specifically designed to allow you to put as many HTTP interactions into one cassette as you want. What problem are you having?

I'd encourage you to send an email describing your issue to the mailing list, where I generally answer VCR questions.

Nikolai Volochaev almost 13 years ago

thank you! could you make a PRO screencast with basics of TTD?

Ryan Bates almost 13 years ago

Thanks for the suggestion. I plan to cover TTD more in future pro episodes.

wiiikiii almost 13 years ago

I am missing the iTunes announcement for this podcast?
Will it comes soon?

Jonathan Tushman almost 13 years ago

VCR for me has been a total game changer. Here is a snip-it to create a @vcr tag for cucumber scenarios:

          ruby
        
Around('@vcr') do |scenario, block|
  s_name = scenario.name.underscore.gsub(/[^\w\/]+/, "_")
  f_name = scenario.feature.name.underscore.gsub(/[^\w\/]+/, "_")
  VCR.use_cassette("/scenarios/#{f_name}/#{s_name}", record: :once) { block.call }
end

Urban Hafner almost 13 years ago

This is a great start. However, it doesn't work with Scenario Outlines. The following does however:

          ruby
        
Around('@vcr') do |scenario, block|
  s_name = scenario.name.underscore.gsub(/[^\w]+/, "_").gsub(/^_/,'').gsub(/_$/,'')
  if scenario.respond_to? :scenario_outline
    feature = scenario.scenario_outline.feature
  else
    feature = scenario.feature
  end
  f_name = feature.name.underscore.gsub(/[^\w\/]+/, "_")
  VCR.use_cassette("/#{f_name}/#{s_name}", record: :once) { block.call }
end

Urban Hafner almost 13 years ago

This still doesn't work when you have cucumber backgrounds as the around hook gets executed after (!) the background is executed.

Graeme Simpson over 12 years ago

Did you manage to get a solution for this?

Thanks.

Matt Parker about 12 years ago

seperate before/after:

          ruby
        
Before do |scenario|
  if scenario.respond_to? :scenario_outline
    feature = scenario.scenario_outline.feature
  else
    feature = scenario.feature
  end

  cassette_name = "#{feature.name.split("\n").first}/#{scenario.name}"
  VCR.insert_cassette(cassette_name)
end

After do
  VCR.eject_cassette
end

Ramon almost 13 years ago

Nice. I was looking for something like this. I tried this, but get this error:

          
        
A VCR cassette is currently in use.  You must eject it before you can turn VCR off. (VCR::Errors::CassetteInUseError)
      /Users/dev/.rvm/gems/ree-1.8.7-2011.03@mclax/gems/vcr-2.0.0.beta2/lib/vcr.rb:124:in `turn_off!'
      /Users/dev/Projects/mclax/features/support/hooks.rb:25:in `After'

Julian Tescher over 12 years ago

VCR 2.0 is out! Looks like lots of these ideas made it in.

For anyone having issues upgrading:
http://myronmars.to/n/dev-blog/2012/03/vcr-2-0-0-released

Janko Marohnić over 12 years ago

The ending with Capybara is like a cherry on top. Such an awesome episode :)

Dana over 12 years ago

Was just looking for a solution while testing a portion of an application which uses google's geocoding service. We're limited to the number of geocoding requests we can make, so I turned to VCR.

I'd swear my reading comprehension is good until I attempt to read a README (no offense intended, Myron).

This screencast had me up and running moments after watching. Thanks much, Ryan and Myron!

Joe Jackson about 12 years ago

For anyone not using rails, there is one tricky bit. here:

          ruby
        
RSpec.configure do |c|
  c.treat_symbols_as_metadata_keys_with_true_values = true
  c.around(:each, :vcr) do |example|
    name = example.metadata[:full_description].split(/\s+/, 2).join("/").underscore.gsub(/[^\w\/]+/, "_")
    options = example.metadata.slice(:record, :match_requests_on).except(:example_group)
    VCR.use_cassette(name, options) { example.call }
  end
end

The underscore method is a rails helper, but is unnecessary here because gsub(/[^\w\/]+/, "_") already takes care of any non-word character that's not a slash.

Johnneylee Jack Rollins almost 12 years ago

There seems to be no #slice method available on the example.metadata object.

          ruby
        
undefined method `slice' for #<RSpec::Core::Metadata:0x007f9ee42ab770>

Myron Marston almost 12 years ago

Slice is a method added by ActiveSupport to Hash, so if you're not using Rails, I'd expect you'd get a NoMethodError like this.

However, you don't need to use Ryan's snippet to get integration with RSpec metadata--that's built in to VCR 2 now.

Ryan requested this a while ago and I was happy to oblige :).

Johnneylee Jack Rollins almost 12 years ago

That is extremely wonderful! Thank you so much for it.

jay thompson almost 11 years ago

Thanks Myron: Now my vcr_config looks like this from Ryan's:

vcr_config.rb:

          vcr_config.rb
        
require 'vcr'

  VCR.configure do |c|
    c.cassette_library_dir = Rails.root.join("spec", "vcr")
    c.hook_into :webmock
    c.configure_rspec_metadata!
    #was :webmock
    #c.filter_sensitive_data('<WSDL>') { "http://www.webservicex.net:80/uszip.asmx?WSDL" }
  end

  RSpec.configure do |c|
    c.treat_symbols_as_metadata_keys_with_true_values = true
#    c.around(:each, :vcr) do |example|
#      name = example.metadata[:full_description].split(/\s+/, 2).join("/").underscore.gsub(/[^\w\/]+/, "_")
#      options = example.metadata.slice(:record, :match_requests_on).except(:example_group)
#      VCR.use_cassette(name, options) { example.call }
#    end
  end

and spec_helper.rb has changed the fakeweb include to webmock

          spec_helper.rb
        
require 'webmock/rspec'

Grayson Wright over 11 years ago

What would you recommend when it comes to the /spec/vcr directory and version control?

I imagine it would be pretty safe to ignore the directory, because the cassette files would be generated on the first test run for each checkout of the repository (assuming you use record: :new_episodes)

On the other hand, if you're communicating with an unreliable server, it could be a pain to re-record the interactions correctly.

Any thoughts?

Myron Marston over 11 years ago

It's a matter of tradeoffs and deciding what's important to you. I tend to check my VCR cassettes into source control, because I like having the history of what the HTTP responses were at a particular point in time. It allows me to git bisect through my history and having passing tests. If the cassettes are not committed to source control, and the HTTP responses have changed, you'll have a very hard time running the tests at an old commit.

However, committing the cassettes does tend to bloat your git repository with lots of extra files, and it makes it easy to wind up with tests that require particular exact cassettes (e.g. because you hand-edited them) to pass. I like that not committing cassettes encourages you to just treat them as a cache.

It's up to you ultimately -- just consider what is more important to you of the pros/cons I've listed here.

Nishutosh over 11 years ago

@rbates Are you thinking to update this one ?

jay thompson almost 11 years ago

in case anyone wants to use VCR for just a piece of a larger test suite, VCR blocks any unapproved HTTP access- and will get in the way of the other tests and they will fail with a warning from VCR (unless hidden behind a rescue block-another story). This was unexpected for me- I want to pick and choose which tests are recorded. I was thinking that the :all option would work, but do not desire to signup for housecleaning on all of the recorded cassettes.

VCR behavior can be modified with the flag set in the config block:

          in vcr_config.rb
        
c.allow_http_connections_when_no_cassette = true

and pass through is allowed for these tests, and what I want.

I hope this helps someone else- this is a great tool thank you so much this cast and this gem.

Conner Smith almost 11 years ago

I need to scroll to the bottom of the comments more often. I forget they are organized oddly.

Louise Glade Rains over 8 years ago

I made use of the filter_sensitive_data option to replace a password in my cassette. This worked great the first time, but when I run the specs again, I get an error:

Failure/Error: VCR.use_cassette(cassette_name, record: :once) do
 URI::InvalidURIError:
   bad URI(is not URI?): https://<DOMAIN>:<PASSWORD>@services.yesmail.com:443/enterprise/composite/subscribeAndSend

Is there a way to deal with this problem?

Thanks for a great episode!
Louise