Merge pull request rmosolgo#211 from rmosolgo/check-typecasting

fix(Typecast) add end-to-end test for interface-to-interface casting

Author: Robert Mosolgo

spec/graphql/interface_type_spec.rb

@@ -53,4 +53,29 @@
       assert_equal(interface.resolve_type(123, nil), :custom_resolve)
     end
   end
+
+  describe "fragments" do
+    let(:query_string) {%|
+    {
+      favoriteEdible {
+        fatContent
+        ... on LocalProduct {
+          origin
+        }
+      }
+    }
+    |}
+    let(:result) { DummySchema.execute(query_string) }
+
+    it "can apply interface fragments to an interface" do
+      expected_result = { "data" => {
+        "favoriteEdible" => {
+          "fatContent" => 0.04,
+          "origin" => "Antiquity",
+        }
+      } }
+
+      assert_equal(expected_result, result)
+    end
+  end
 end

spec/graphql/introspection/type_type_spec.rb

@@ -36,7 +36,8 @@
       "milkType"=>{
         "interfaces"=>[
           {"name"=>"Edible"},
-          {"name"=>"AnimalProduct"}
+          {"name"=>"AnimalProduct"},
+          {"name"=>"LocalProduct"},
         ],
         "fields"=>[
           {"type"=>{"name"=>"Non-Null", "ofType"=>{"name"=>"Float"}}},

spec/graphql/object_type_spec.rb

@@ -15,7 +15,7 @@
   end
 
   it "may have interfaces" do
-    assert_equal([EdibleInterface, AnimalProductInterface], type.interfaces)
+    assert_equal([EdibleInterface, AnimalProductInterface, LocalProductInterface], type.interfaces)
   end
 
   describe '#get_field ' do

spec/graphql/schema/reduce_types_spec.rb

@@ -14,6 +14,7 @@ def reduce_types(types)
       "Int" => GraphQL::INT_TYPE,
       "Edible" => EdibleInterface,
       "AnimalProduct" => AnimalProductInterface,
+      "LocalProduct" => LocalProductInterface,
     }
     result = reduce_types([CheeseType])
     assert_equal(expected.keys, result.keys)

spec/graphql/union_type_spec.rb

@@ -12,11 +12,11 @@
       possible_types(types)
     }
   }
+
   it "has a name" do
     assert_equal("MyUnion", union.name)
   end
 
-
   it "infers type from an object" do
     assert_equal(CheeseType, DairyProductUnion.resolve_type(CHEESES[1], OpenStruct.new(schema: DummySchema)))
   end
@@ -29,6 +29,33 @@
     assert_equal(false, union.include?(type_3))
   end
 
+  describe "typecasting from union to union" do
+    let(:result) { DummySchema.execute(query_string) }
+    let(:query_string) {%|
+      {
+        allDairy {
+          dairyName: __typename
+          ... on Beverage {
+            bevName: __typename
+            ... on Milk {
+              flavors
+            }
+          }
+        }
+      }
+    |}
+
+    it "casts if the object belongs to both unions" do
+      expected_result = [
+        {"dairyName"=>"Cheese"},
+        {"dairyName"=>"Cheese"},
+        {"dairyName"=>"Cheese"},
+        {"dairyName"=>"Milk", "bevName"=>"Milk", "flavors"=>["Natural", "Chocolate", "Strawberry"]},
+      ]
+      assert_equal expected_result, result["data"]["allDairy"]
+    end
+  end
+
   describe "list of union type" do
     describe "fragment spreads" do
       let(:result) { DummySchema.execute(query_string) }

spec/support/dairy_app.rb

@@ -5,6 +5,12 @@ class NoSuchDairyError < StandardError; end
 GraphQL::Field.accepts_definitions(joins: GraphQL::Define.assign_metadata_key(:joins))
 GraphQL::BaseType.accepts_definitions(class_names: GraphQL::Define.assign_metadata_key(:class_names))
 
+LocalProductInterface = GraphQL::InterfaceType.define do
+  name "LocalProduct"
+  description "Something that comes from somewhere"
+  field :origin, !types.String, "Place the thing comes from"
+end
+
 EdibleInterface = GraphQL::InterfaceType.define do
   name "Edible"
   description "Something you can eat, yum"
@@ -18,6 +24,12 @@ class NoSuchDairyError < StandardError; end
   field :source, !types.String, "Animal which produced this product"
 end
 
+BeverageUnion = GraphQL::UnionType.define do
+  name "Beverage"
+  description "Something you can drink"
+  possible_types [MilkType]
+end
+
 DairyAnimalEnum = GraphQL::EnumType.define do
   name "DairyAnimal"
   description "An animal which can yield milk"
@@ -31,7 +43,7 @@ class NoSuchDairyError < StandardError; end
   name "Cheese"
   class_names ["Cheese"]
   description "Cultured dairy product"
-  interfaces [EdibleInterface, AnimalProductInterface]
+  interfaces [EdibleInterface, AnimalProductInterface, LocalProductInterface]
 
   # Can have (name, type, desc)
   field :id, !types.Int, "Unique identifier"
@@ -78,7 +90,7 @@ class NoSuchDairyError < StandardError; end
 MilkType = GraphQL::ObjectType.define do
   name "Milk"
   description "Dairy beverage"
-  interfaces [EdibleInterface, AnimalProductInterface]
+  interfaces [EdibleInterface, AnimalProductInterface, LocalProductInterface]
   field :id, !types.ID
   field :source, DairyAnimalEnum, "Animal which produced this milk", hash_key: :source
   field :origin, !types.String, "Place the milk comes from"
@@ -317,6 +329,6 @@ def self.create(type:, data:)
   mutation: DairyAppMutationType,
   subscription: SubscriptionType,
   max_depth: 5,
-  types: [HoneyType],
+  types: [HoneyType, BeverageUnion],
 )
 DummySchema.rescue_from(NoSuchDairyError) { |err| err.message  }