Sorbet support (initial)

[iurev]

Implementation proposal

Initial setup details

1. Add sorbet to TYPE_CHECKERS in core.rb
2. Use lib/type_check/ruby.rb as a template for the new checker lib/type_check/sorbet.rb (and tests too)

Sorbet library integration details

Option 1: Use Sorbet methods inside typecheck!

1. Find the original method's signature (see below)
2. Use validate_call and related methods inside typecheck!

Looking for the signature of the original method

T::Private::Methods.signature_for_method(ReceiverClassName.instance_method :method_name)

Typecheck 2: CallValidation

It is possible to check types of incoming arguments, which I am also going to implement using CallValidation

Useful Mock Suey methods

I include methods from Mock Suey that might be used during this feature development, or at least their understanding is necessary for me to write the code. They also might be helpful during code review.

Rspec before
  MockSuey.cook
    setup_type_checker
    signature_load_dirs
    on_mocked_call: adds type_checker.typecheck! lambda to array @on_mocked_callbacks

Rspec after
    MockSuey.eat # Probably nothing to see in here for now

Rspec::MethodDouble.prepend
    ProxyMethodInvokedHook # wraps mock method and setups type checking
      MockSuey.handle_method_call

MockSuey.handle_method_call(call_obj: MockSuey::MethodCall)
    lazy init type_checker
      load_dirs # Might cause problems, need to research how to work with sorbet

type_checker.typecheck!

Useful Sorbet methods

I am going to use sorbet-runtime as it includes signatures and typechecker.

sig method

module Methods which contains the most important source code for me.

sig.rb:
  sig method

T::Private::Methods:
	declare_sig
	install_hooks on the class or module to extend with MethodHooks, SingletonMethodHooks
	reset! current declaration after installing the hooks
	set active_declaration (DeclarationBlock class)
	
	method_added
	_on_method_added
		sig_block
		replace method with a wrapper
		add method to @sig_wrappers using key

      CallValidation.validate_call

Other useful things:

caller_location

sorbet configuration

method_added

[palkan]

Thanks!

Amazing work, left some comments/questions, but I think we'll be ready to merge it soon.

Also, can you please rebase on top of master? I fixed the RBS issues making CI fail.

[palkan]

It reminds me this RSpec Sorbet integration: https://github.com/samuelgiles/rspec-sorbet/blob/4d0e6479453b3b4ef36d2d6a2df8282ae559368b/lib/rspec/sorbet/doubles.rb#L104

Are we doing something similar here? Maybe, we can rely on the rspec-sorbet gem? (That's something we can consider in the future)

[iurev]

It uses a similar approach and calls the same method T::Configuration.call_validation_error_handler from Sorbet.

The first problem I see here is that they may not work together at the moment. The reason for that is this line:
T::Configuration.send(:call_validation_error_handler_default, signature, opts)
Most probably, it will not call the handler defined in the gem rspec-sorbet

I will try to reproduce the error and write a comment about the result below. Anyway, it should be easy to fix. RSpec Sorbet uses a correct approach to override this method.

It should be possible to integrate RSpec Sorbet gem if this is needed I guess.

[iurev]

I fixed this issue in another branch: link to the commit
I will add this change to the master branch if you don't mind.

[palkan]

Maybe, we can somehow distinguish stdlib types from custom types, so we can ignore only missing stdlib types? Any ideas?

[iurev]

Thanks for the suggestion, it should be easy to implement.

# sorbet.rb
def sig_is_missing(method_call, raise_on_missing)
  return unless raise_on_missing
  return unless method_call.receiver_class < T::Sig # By adding this line to check if the class uses signatures
  raise MissingSignature, RAISE_ON_MISSING_MESSAGE
end

I should also mention that I missed an important part of the problem here and I should update the readme to include this information.

If a signature is described in a .rb file, it will be used by sorbet-runtime and type checking will be available. One of the gems that is using sorbet signatures is ShopifyAPI for example.

However, many signatures are declared inside .rbi files, like 1) signatures for stdlib and core types and 2) signatures for most libraries including rails. Unfortunately, these types cannot be loaded into runtime at the moment. Therefore, it's not possible to type check their mocks yet.

[iurev]

I also updated readme to make the explanation more understandable.
link to the comment

I can add this commit to the master branch too.

[iurev]

Defining a singleton method on a mocked object might cause a problem. It's better to either .dup or create a new empty object for the purpose of holding this method.

[iurev]

There's a room for improvement: the variable method_call is passed too many times.
Therefore, it should be better to extract these functions into a class or a structure MethodCheck, where method_call (and mocked_obj, arguments, method_name, etc...) will be available as instance variables.

[palkan]

What's the purpose of these changes?

[iurev]

I made these changes because I wanted to run the command right from the terminal and to make the command variable look "prettier".

This is how it used to be:

bundle exec ruby /home/yu/projects/mock-suey/spec/support/../../bin/rspec  double_fixture.rb

which runs from spec/fixtures/rspec. There's a part ../../, which I removed.

This is how it looks now:

bundle exec ruby /home/yu/projects/mock-suey/bin/rspec  spec/fixtures/rspec/stored_mocked_calls_fixture.rb

It runs from project root.

[Envek]

Just out of curiosity: why you swapped these two arguments of == operator?

[iurev]

I reversed these arguments because rubocop showed me a warning Style/YodaCondition. link to the rule.

It looks a bit more logical to put the arg first: "argument equals constant" vs "constant equals argument".
Anyway, I don't mind both kinds of comparations. It is easy to read both of them.