fix: service field context (#50)

* fix service field context

* require keyword context

* switch to positional arguments instead of keyword

* adds tests

* rubocop

* switch back to keyword arguments

Author: matthewjf

lib/apollo-federation/service_field.rb

@@ -10,7 +10,7 @@ module ServiceField
     field(:_service, Service, null: false)
 
     def _service
-      { sdl: context.schema.class.federation_sdl(context) }
+      { sdl: context.schema.class.federation_sdl(context: context) }
     end
   end
 end

spec/apollo-federation/service_field_spec.rb

@@ -371,4 +371,76 @@ def execute_sdl(schema)
       GRAPHQL
     )
   end
+
+  context 'with a filter' do
+    let(:schema) do
+      product = Class.new(base_object) do
+        graphql_name 'Product'
+
+        field :upc, String, null: false
+      end
+
+      query_obj = Class.new(base_object) do
+        graphql_name 'Query'
+
+        field :product, product, null: true
+      end
+
+      Class.new(base_schema) do
+        query query_obj
+      end
+    end
+    let(:filter) do
+      class PermissionWhitelist
+        def call(_schema_member, context)
+          context[:user_role] == :admin
+        end
+      end
+
+      PermissionWhitelist.new
+    end
+    let(:context) { { user_role: :admin } }
+    let(:executed_with_context) do
+      schema.execute('{ _service { sdl } }', only: filter, context: context)
+    end
+    let(:executed_without_context) { schema.execute('{ _service { sdl } }', only: filter) }
+
+    it 'passes context to filters' do
+      expect(executed_with_context['data']['_service']['sdl']).to match_sdl(
+        <<~GRAPHQL,
+          type Product {
+            upc: String!
+          }
+
+          type Query {
+            product: Product
+          }
+        GRAPHQL
+      )
+    end
+
+    it 'works without context' do
+      expect(executed_without_context['errors']).to(
+        match_array(
+          [
+            include('message' => "Field '_service' doesn't exist on type 'Query'"),
+          ],
+        ),
+      )
+    end
+
+    context 'when not authorized' do
+      let(:context) { { user_role: :foo } }
+
+      it 'returns an error message' do
+        expect(executed_with_context['errors']).to(
+          match_array(
+            [
+              include('message' => "Field '_service' doesn't exist on type 'Query'"),
+            ],
+          ),
+        )
+      end
+    end
+  end
 end