Add linting feature through Grape.config and lint_api! method

Add spec
All specs are now linted

Author: ericproulx

lib/grape.rb

@@ -75,6 +75,7 @@ def self.deprecator
 
   configure do |config|
     config.param_builder = :hash_with_indifferent_access
+    config.lint_api = false
     config.compile_methods!
   end
 end

lib/grape/dsl/routing.rb

@@ -81,6 +81,10 @@ def do_not_route_options!
           namespace_inheritable(:do_not_route_options, true)
         end
 
+        def lint_api!
+          namespace_inheritable(:lint_api, true)
+        end
+
         def do_not_document!
           namespace_inheritable(:do_not_document, true)
         end

lib/grape/endpoint.rb

@@ -358,6 +358,7 @@ def build_stack(helpers)
       format = namespace_inheritable(:format)
 
       stack.use Rack::Head
+      stack.use Rack::Lint if lint_api?
       stack.use Class.new(Grape::Middleware::Error),
                 helpers: helpers,
                 format: format,
@@ -408,5 +409,9 @@ def build_response_cookies
         Rack::Utils.set_cookie_header! header, name, cookie_value
       end
     end
+
+    def lint_api?
+      namespace_inheritable(:lint_api) || Grape.config.lint_api
+    end
   end
 end

spec/grape/api_spec.rb

@@ -4738,4 +4738,25 @@ def uniqe_id_route
       expect(last_response.body).to eq('unknown params_builder: unknown')
     end
   end
+
+  describe '.lint_api!' do
+    let(:app) do
+      Class.new(described_class) do
+        lint_api!
+        get '/' do
+          status 42
+        end
+      end
+    end
+
+    around do |example|
+      Grape.config.lint_api = false
+      example.run
+      Grape.config.lint_api = true
+    end
+
+    it 'raises a Rack::Lint error' do
+      expect { get '/' }.to raise_error(Rack::Lint::LintError, 'Status must be an Integer >=100')
+    end
+  end
 end

spec/spec_helper.rb

@@ -13,6 +13,7 @@
   end
 end
 
+Grape.config.lint_api = true # lint all apis by default
 Grape::Util::Registry.include(Deregister)
 # issue with ruby 2.7 with ^. We need to extend it again
 Grape::Validations.extend(Grape::Util::Registry) if Gem::Version.new(RUBY_VERSION).release < Gem::Version.new('3.0')