Fix resolveReference being generated as required when using generateInternalResolversIfNeeded.__resolveReference (#10230)

* Fix generate generateInternalResolversIfNeeded.__resolveReference making the resolver required

* Add changeset

Author: eddeee888

Diff for: .changeset/orange-pillows-decide.md

@@ -0,0 +1,10 @@
+---
+'@graphql-codegen/visitor-plugin-common': patch
+'@graphql-codegen/typescript-resolvers': patch
+---
+
+Fix generateInternalResolversIfNeeded.\_\_resolveReference making the resolver required
+
+`__resolveReference`'s default behaviour when not declared is to pass the ref to subsequent resolvers i.e. becoming the `parent`. So, it means we don't have to make this resolver required.
+
+This patch makes `__resolveReference` optional when `generateInternalResolversIfNeeded.__resolveReference` is set to true.

Diff for: packages/plugins/other/visitor-plugin-common/src/base-resolvers-visitor.ts

@@ -1531,7 +1531,6 @@ export class BaseResolversVisitor<
           if (!federationDetails || federationDetails.resolvableKeyDirectives.length === 0) {
             return '';
           }
-          signature.modifier = ''; // if a federation type has resolvable @key, then it should be required
         }
 
         this._federation.setMeta(parentType.name, { hasResolveReference: true });

Diff for: packages/plugins/typescript/resolvers/tests/ts-resolvers.federation.spec.ts

@@ -212,7 +212,7 @@ describe('TypeScript Resolvers Plugin + Apollo Federation', () => {
       // User should have __resolveReference because it has resolvable @key (by default)
       expect(content).toBeSimilarStringTo(`
     export type UserResolvers<ContextType = any, ParentType extends ResolversParentTypes['User'] = ResolversParentTypes['User']> = {
-      __resolveReference: ReferenceResolver<Maybe<ResolversTypes['User']>, { __typename: 'User' } & GraphQLRecursivePick<ParentType, {"id":true}>, ContextType>;
+      __resolveReference?: ReferenceResolver<Maybe<ResolversTypes['User']>, { __typename: 'User' } & GraphQLRecursivePick<ParentType, {"id":true}>, ContextType>;
       id?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       name?: Resolver<Maybe<ResolversTypes['String']>, ParentType, ContextType>;
       username?: Resolver<Maybe<ResolversTypes['String']>, ParentType, ContextType>;
@@ -223,7 +223,7 @@ describe('TypeScript Resolvers Plugin + Apollo Federation', () => {
       // SingleResolvable has __resolveReference because it has resolvable: true
       expect(content).toBeSimilarStringTo(`
     export type SingleResolvableResolvers<ContextType = any, ParentType extends ResolversParentTypes['SingleResolvable'] = ResolversParentTypes['SingleResolvable']> = {
-      __resolveReference: ReferenceResolver<Maybe<ResolversTypes['SingleResolvable']>, { __typename: 'SingleResolvable' } & GraphQLRecursivePick<ParentType, {"id":true}>, ContextType>;
+      __resolveReference?: ReferenceResolver<Maybe<ResolversTypes['SingleResolvable']>, { __typename: 'SingleResolvable' } & GraphQLRecursivePick<ParentType, {"id":true}>, ContextType>;
       id?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       __isTypeOf?: IsTypeOfResolverFn<ParentType, ContextType>;
     };
@@ -240,7 +240,7 @@ describe('TypeScript Resolvers Plugin + Apollo Federation', () => {
       // AtLeastOneResolvable has __resolveReference because it at least one resolvable
       expect(content).toBeSimilarStringTo(`
     export type AtLeastOneResolvableResolvers<ContextType = any, ParentType extends ResolversParentTypes['AtLeastOneResolvable'] = ResolversParentTypes['AtLeastOneResolvable']> = {
-      __resolveReference: ReferenceResolver<Maybe<ResolversTypes['AtLeastOneResolvable']>, { __typename: 'AtLeastOneResolvable' } & GraphQLRecursivePick<ParentType, {"id2":true}>, ContextType>;
+      __resolveReference?: ReferenceResolver<Maybe<ResolversTypes['AtLeastOneResolvable']>, { __typename: 'AtLeastOneResolvable' } & GraphQLRecursivePick<ParentType, {"id2":true}>, ContextType>;
       id?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       id2?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       id3?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
@@ -251,7 +251,7 @@ describe('TypeScript Resolvers Plugin + Apollo Federation', () => {
       // MixedResolvable has __resolveReference and references for resolvable keys
       expect(content).toBeSimilarStringTo(`
     export type MixedResolvableResolvers<ContextType = any, ParentType extends ResolversParentTypes['MixedResolvable'] = ResolversParentTypes['MixedResolvable']> = {
-      __resolveReference: ReferenceResolver<Maybe<ResolversTypes['MixedResolvable']>, { __typename: 'MixedResolvable' } & (GraphQLRecursivePick<ParentType, {"id":true}> | GraphQLRecursivePick<ParentType, {"id2":true}>), ContextType>;
+      __resolveReference?: ReferenceResolver<Maybe<ResolversTypes['MixedResolvable']>, { __typename: 'MixedResolvable' } & (GraphQLRecursivePick<ParentType, {"id":true}> | GraphQLRecursivePick<ParentType, {"id2":true}>), ContextType>;
       id?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       id2?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;
       id3?: Resolver<ResolversTypes['ID'], ParentType, ContextType>;