New feature : linting

docker/Dockerfile

@@ -7,7 +7,7 @@ ENV RUBYOPT --enable-frozen-string-literal --yjit
 ENV LD_PRELOAD libjemalloc.so.2
 ENV MALLOC_CONF dirty_decay_ms:1000,narenas:2,background_thread:true
 
-RUN apk add --update --no-cache make gcc git libc-dev gcompat jemalloc && \
+RUN apk add --update --no-cache make gcc git libc-dev yaml-dev gcompat jemalloc && \
     gem update --system && gem install bundler
 
 WORKDIR $LIB_PATH

lib/grape.rb

@@ -75,6 +75,7 @@ def self.deprecator
 
   configure do |config|
     config.param_builder = :hash_with_indifferent_access
+    config.lint = 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!
+          namespace_inheritable(:lint, 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?
       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?
+      namespace_inheritable(:lint) || Grape.config.lint
+    end
   end
 end

spec/grape/api_spec.rb

@@ -4738,4 +4738,26 @@ def uniqe_id_route
       expect(last_response.body).to eq('unknown params_builder: unknown')
     end
   end
+
+  describe '.lint!' do
+    let(:app) do
+      Class.new(described_class) do
+        lint!
+        get '/' do
+          status 42
+        end
+      end
+    end
+
+    around do |example|
+      Grape.config.lint = false
+      example.run
+      Grape.config.lint = true
+    end
+
+    it 'raises a Rack::Lint error' do
+      # Status must be an Integer >= 100
+      expect { get '/' }.to raise_error(Rack::Lint::LintError)
+    end
+  end
 end

spec/integration/rails/mounting_spec.rb

@@ -17,7 +17,7 @@
       ActiveSupport::Dependencies.autoload_paths = []
       ActiveSupport::Dependencies.autoload_once_paths = []
 
-      Class.new(Rails::Application) do
+      app = Class.new(Rails::Application) do
         config.eager_load = false
         config.load_defaults "#{Rails::VERSION::MAJOR}.#{Rails::VERSION::MINOR}"
         config.api_only = true
@@ -28,15 +28,16 @@
           mount GrapeApi => '/'
 
           get 'up', to: lambda { |_env|
-            ['200', {}, ['hello world']]
+            [200, {}, ['hello world']]
           }
         end
       end
+      app.initialize!
+      Rack::Lint.new(app)
     end
 
     before do
       stub_const('GrapeApi', api)
-      app.initialize!
     end
 
     it 'cascades' do

spec/spec_helper.rb

@@ -13,6 +13,7 @@
   end
 end
 
+Grape.config.lint = 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')