Remember Using contracts.ruby With RSpec ?

RSpec mocks violate all :class contracts because is_a?(ClassName) returns false for mock. That post describes 2 possible solutions:

• stub :is_a?: allow(my_double).to receive(:is_a?).with(MyClass).and_return(true), or
• use contracts-rspec gem, that patches instance_double RSpec helper.

Custom validators

Since custom validators have finally landed here: egonShiele/contracts.ruby#159, now you can just override :class validator to accept all RSpec mocks:

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# Make contracts accept all RSpec doubles
Contract.override_validator(:class) do |contract|
  lambda do |arg|
    arg.is_a?(RSpec::Mocks::Double) ||
      arg.is_a?(contract)
  end
end

Now, RSpec mocks will not violate all the :class contracts.

More information can be found here: Providing your own custom validators.

Additionally this refactoring enabled valuable speed optimization for complex contracts - validators for them will be evaluated only once and memoized.

Links

• Previous part
• contracts.ruby: https://github.com/egonSchiele/contracts.ruby
• contracts.ruby chat: https://gitter.im/egonSchiele/contracts.ruby
• Mentioned PR: https://github.com/egonSchiele/contracts.ruby/pull/159
• Introduction to contracts.ruby
• Great contracts.ruby tutorial
• Full fledged documentation PR: see here staging docs: https://relishapp.com/contracts-staging/contracts-ruby/docs

Thanks!

If you have any questions, suggestions or just want to chat about how contracts.ruby is awesome, you can ping me on twitter @tdd_fellow. If you have any issues using contracts.ruby you can create issues on corresponding github project. Pull requests are welcome!

Comments on hackernews.

Happy coding! @tdd_fellow on twitter.