Raise an error when calling custom matcher without using `.and`

[AlecksJohannes]

Subject of the issue

Hi there folks 👋 ,

First of all, thank you for this great gem! I created this issue here just to offer a small idea, I encountered a small scenario when using custom matchers.

Let's say we have this custom matcher

RSpec::Matchers.define(:create_some_model) do
  chain(:method1) {}
  chain(:method2) {}
  chain(:method3) {}
  ...
end

describe do
  it do
    expect { some_action }.to create_some_model(Model).method1.method2.method3.create_some_model(Model2)
  end
end

As you can see, it is easy to make mistake as we sometime might forget to add .and between create_some_model and this could create false-positive test result as it will only run create_some_model(Model2). I understand that this is more human error but I would love to prevent it.

My idea is in RSpec::Matchers::DSL::Matcher, we also define

class RSpec::Matchers::DSL::Matcher
  define_method(method) do
    raise "You did not use .and between your 'create_some_model' test expectation"
  end
end

So calling create_some_model twice will resulting in error like that. There is one catch with this approach is you cannot call the same create_some_model inside the matcher itself but IMHO, I don't think it is a good idea to do such

RSpec::Matchers.define(:create_some_model) do
  chain(:method1) {}
  chain(:method2) {}
  chain(:method3) {}
  
 def something
   expect { }.to create_some_model <-- this doesn't work
 end
  ...
end

I can create a PR to apply this idea, please let me know what do you guys think. Thank you for reading!

P/S:

There is 1 more approach besides that is to get rid of the defined custom matcher method from RSpec::Matchers::DSL::Matcher but if we do that we also have to get rid of the method_missing as well which I don't think it is a good idea.

Your environment

• Ruby version: 2.7.5
• rspec-expectations version: 3.13.0.pre