fix(object-authorization): Fix object authorization for interfaces

Very similar to jungsoft#26, but for interfaces instead of unions

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/middlewares/object_authorization.ex

@@ -80,7 +80,7 @@ defmodule Rajska.ObjectAuthorization do
 
   # When is a Scalar, Custom or Enum type, authorize.
   defp authorize_object(%type{} = object, fields, resolution)
-  when type in [Scalar, Custom, Type.Enum, Type.Enum.Value, Type.Union] do
+  when type in [Scalar, Custom, Type.Enum, Type.Enum.Value, Type.Union, Type.Interface] do
     put_result(true, fields, resolution, object)
   end
 
@@ -118,6 +118,13 @@ defmodule Rajska.ObjectAuthorization do
     authorize(schema_node, selections ++ tail, resolution)
   end
 
+  defp find_associations(
+    [%{schema_node: %Type.Interface{} = schema_node, selections: selections} | tail],
+    resolution
+  ) do
+    authorize(schema_node, selections ++ tail, resolution)
+  end
+
   defp find_associations(
     [%{schema_node: schema_node, selections: selections} | tail],
     resolution

test/middlewares/object_authorization_test.exs

@@ -57,10 +57,18 @@ defmodule Rajska.ObjectAuthorizationTest do
           {:ok, %{name: "bob"}}
         end
       end
+
+      field :interface_query, :interface do
+        middleware Rajska.QueryAuthorization, [permit: :all, scope: false]
+        resolve fn _, _ ->
+          {:ok, %{name: "bob"}}
+        end
+      end
     end
 
     object :wallet_balance do
       meta :authorize, :admin
+      interfaces([:interface])
 
       field :total, :integer
     end
@@ -80,6 +88,7 @@ defmodule Rajska.ObjectAuthorizationTest do
 
     object :user do
       meta :authorize, :all
+      interfaces([:interface])
 
       field :email, :string
       field :name, :string
@@ -94,6 +103,13 @@ defmodule Rajska.ObjectAuthorizationTest do
         %{total: _}, _ -> :wallet_balance
       end
     end
+
+    interface :interface do
+      resolve_type fn
+        %{name: _}, _ -> :user
+        %{total: _}, _ -> :wallet_balance
+      end
+    end
   end
 
   test "Public query with public object works for everyone" do
@@ -174,6 +190,13 @@ defmodule Rajska.ObjectAuthorizationTest do
     refute Map.has_key?(result, :errors)
   end
 
+  test "Works for interfaces" do
+    {:ok, result} = Absinthe.run(interface_query(), __MODULE__.Schema, context: %{current_user: %{role: :admin}})
+
+    assert %{data: %{"interfaceQuery" => %{"name" => "bob"}}} = result
+    refute Map.has_key?(result, :errors)
+  end
+
   test "Works when using fragments and user has access" do
     {:ok, result} = Absinthe.run(fragment_query_user(), __MODULE__.Schema, context: %{current_user: %{role: :user}})
 
@@ -266,6 +289,21 @@ defmodule Rajska.ObjectAuthorizationTest do
     """
   end
 
+  defp interface_query do
+    """
+    {
+      interfaceQuery {
+        ... on User {
+          name
+        }
+        ... on WalletBalance {
+          total
+        }
+      }
+    }
+    """
+  end
+
   defp fragment_query_user do
     """
     fragment userFields on User {