Improve SDL directive argument coercion

Author: rmosolgo

lib/graphql/schema/directive.rb

@@ -142,7 +142,14 @@ def initialize(owner, **arguments)
                 # However, we're using result coercion here to go from Ruby value
                 # to GraphQL value, so it doesn't have that feature.
                 # Keep the GraphQL-type behavior but implement it manually:
-                coerce_value = [coerce_value]
+                wrap_type = arg_type
+                while wrap_type.list?
+                  if wrap_type.non_null?
+                    wrap_type = wrap_type.of_type
+                  end
+                  wrap_type = wrap_type.of_type
+                  coerce_value = [coerce_value]
+                end
               end
               arg_type.coerce_isolated_result(coerce_value)
             rescue GraphQL::Schema::Enum::UnresolvedValueError

spec/graphql/schema/build_from_definition_spec.rb

@@ -1921,4 +1921,20 @@ module MyInterface
     GRAPHQL
     GraphQL::Schema.from_definition(schema_sdl)
   end
+
+  it "works with invalid directive argument value" do
+    sdl = <<~EOS
+      directive @requiresScopes(scopes: [[String]]) on FIELD_DEFINITION
+
+      type Query {
+        product: Product
+      }
+
+      type Product {
+        shippingEstimate: String @requiresScopes(scopes: "shipping")
+      }
+    EOS
+
+    assert GraphQL::Schema.from_definition(sdl).to_definition
+  end
 end