[Bugfix] Handle deeply-nested dependent params (ruby-grape#1661)

* Repro issue ruby-grape#1659

* [Fix] Handle deeply-nested dependencies with `given`.

Behind the scenes, each call to `requires` or other params DSL method
pushes an entry onto a flat list of validators. The nesting structure
that your parameters can take on is tracked as an up-tree separately
on each scope, but that relationship isn't used to traverse the validations.
So, when I moved the dependency checking out of `should_validate?` and into
the actual validation, the `given` dependency stopped taking effect after
you nested parameters more than one level deep underneath.

To restore the behavior, I made the validation check recursively upwards
to see if it should or should not validate that scope.

* Add changelog entry.

CHANGELOG.md

@@ -4,8 +4,8 @@
 
 #### Fixes
 
+* [#1661](https://github.com/ruby-grape/grape/pull/1661): Handle deeply-nested dependencies correctly - [@rnubel](https://github.com/rnubel), [@jnardone](https://github.com/jnardone).
 * [#1625](https://github.com/ruby-grape/grape/pull/1625): Handle `given` correctly when nested in Array params - [@rnubel](https://github.com/rnubel), [@avellable](https://github.com/avellable).
-* Your contribution here.
 
 ### 0.19.2 (4/12/2017)
 

lib/grape/validations/params_scope.rb

@@ -46,7 +46,11 @@ def should_validate?(parameters)
         parent.should_validate?(parameters)
       end
 
-      def meets_dependency?(params)
+      def meets_dependency?(params, request_params)
+        if @parent.present? && !@parent.meets_dependency?(@parent.params(request_params), request_params)
+          return false
+        end
+
         return true unless @dependent_on
 
         params = params.with_indifferent_access

lib/grape/validations/validators/base.rb

@@ -41,7 +41,7 @@ def validate!(params)
         array_errors = []
         attributes.each do |resource_params, attr_name|
           next unless @required || (resource_params.respond_to?(:key?) && resource_params.key?(attr_name))
-          next unless @scope.meets_dependency?(resource_params)
+          next unless @scope.meets_dependency?(resource_params, params)
 
           begin
             validate_param!(attr_name, resource_params)

spec/grape/validations/params_scope_spec.rb

@@ -418,6 +418,46 @@ def initialize(value)
       end.to raise_error(Grape::Exceptions::UnknownParameter)
     end
 
+    it 'does not validate nested requires when given is false' do
+      subject.params do
+        requires :a, type: String, allow_blank: false, values: %w(x y z)
+        given a: ->(val) { val == 'x' } do
+          requires :inner1, type: Hash, allow_blank: false do
+            requires :foo, type: Integer, allow_blank: false
+          end
+        end
+        given a: ->(val) { val == 'y' } do
+          requires :inner2, type: Hash, allow_blank: false do
+            requires :bar, type: Integer, allow_blank: false
+            requires :baz, type: Array, allow_blank: false do
+              requires :baz_category, type: String, allow_blank: false
+            end
+          end
+        end
+        given a: ->(val) { val == 'z' } do
+          requires :inner3, type: Array, allow_blank: false do
+            requires :bar, type: Integer, allow_blank: false
+            requires :baz, type: Array, allow_blank: false do
+              requires :baz_category, type: String, allow_blank: false
+            end
+          end
+        end
+      end
+      subject.get('/varying') { declared(params).to_json }
+
+      get '/varying', a: 'x', inner1: { foo: 1 }
+      expect(last_response.status).to eq(200)
+
+      get '/varying', a: 'y', inner2: { bar: 2, baz: [{ baz_category: 'barstools' }] }
+      expect(last_response.status).to eq(200)
+
+      get '/varying', a: 'y', inner2: { bar: 2, baz: [{ unrelated: 'yep' }] }
+      expect(last_response.status).to eq(400)
+
+      get '/varying', a: 'z', inner3: [{ bar: 3, baz: [{ baz_category: 'barstools' }] }]
+      expect(last_response.status).to eq(200)
+    end
+
     it 'includes the parameter within #declared(params)' do
       get '/test', a: true, b: true