CODEGEN-859 [graphql-modules-preset] Fix __isTypeOf getting picked from from all objects

.changeset/lemon-insects-attend.md

@@ -0,0 +1,5 @@
+---
+'@graphql-codegen/graphql-modules-preset': patch
+---
+
+Fix \_\_isTypeOf wrongly picked on objects that are not implementing types or union members

packages/presets/graphql-modules/src/builder.ts

@@ -34,6 +34,7 @@ type RegistryKeys = 'objects' | 'inputs' | 'interfaces' | 'scalars' | 'unions' |
 type Registry = Record<RegistryKeys, string[]>;
 const registryKeys: RegistryKeys[] = ['objects', 'inputs', 'interfaces', 'scalars', 'unions', 'enums'];
 const resolverKeys: Array<Extract<RegistryKeys, 'objects' | 'enums' | 'scalars'>> = ['scalars', 'objects', 'enums'];
+const withIsTypeOfKeys: Array<'objects'> = ['objects'];
 
 export function buildModule(
   name: string,
@@ -65,6 +66,7 @@ export function buildModule(
   const picks: Record<RegistryKeys, Record<string, string[]>> = createObject(registryKeys, () => ({}));
   const defined: Registry = createObject(registryKeys, () => []);
   const extended: Registry = createObject(registryKeys, () => []);
+  const withIsTypeOf: { objects: string[] } = createObject(withIsTypeOfKeys, () => []);
 
   // List of types used in objects, fields, arguments etc
   const usedTypes = collectUsedTypes(doc);
@@ -216,7 +218,9 @@ export function buildModule(
             'DefinedFields',
             // In case of enabled `requireRootResolvers` flag, the preset has to produce a non-optional properties.
             requireRootResolvers && rootTypes.includes(name),
-            !rootTypes.includes(name) && defined.objects.includes(name) ? ` | '__isTypeOf'` : ''
+            !rootTypes.includes(name) && defined.objects.includes(name) && withIsTypeOf.objects.includes(name)
+              ? ` | '__isTypeOf'`
+              : ''
           )
         )
         .join('\n'),
@@ -405,6 +409,11 @@ export function buildModule(
       case Kind.OBJECT_TYPE_DEFINITION: {
         defined.objects.push(name);
         collectFields(node, picks.objects);
+
+        if (node.interfaces?.length > 0) {
+          withIsTypeOf.objects.push(name);
+        }
+
         break;
       }
 
@@ -433,6 +442,10 @@ export function buildModule(
 
       case Kind.UNION_TYPE_DEFINITION: {
         defined.unions.push(name);
+
+        for (const namedType of node.types || []) {
+          pushUnique(withIsTypeOf.objects, namedType.name.value);
+        }
         break;
       }
     }
@@ -453,6 +466,10 @@ export function buildModule(
 
         pushUnique(extended.objects, name);
 
+        if (node.interfaces?.length > 0) {
+          pushUnique(withIsTypeOf.objects, name);
+        }
+
         break;
       }
 

packages/presets/graphql-modules/tests/builder.spec.ts

@@ -479,3 +479,90 @@ test('should generate a signature for ResolveMiddleware (with widlcards)', () =>
     };
   `);
 });
+
+test('only picks __isTypeOf from implementing types (of Interfaces) and union members', () => {
+  const output = buildModule(
+    'test',
+    parse(/* GraphQL */ `
+      type Query {
+        me: User
+        pet: Pet
+        offer: Offer
+      }
+
+      type User {
+        id: ID!
+        username: String!
+      }
+
+      interface Pet {
+        id: ID!
+        name: String!
+      }
+      type Cat implements Pet {
+        id: ID!
+        name: String!
+        canScratch: Boolean!
+      }
+      type Dog implements Pet {
+        id: ID!
+        name: String!
+        canBark: Boolean!
+      }
+      type Elephant {
+        id: ID!
+      }
+      extend type Elephant implements Pet {
+        name: String!
+        hasTrunk: Boolean!
+      }
+
+      union Offer = Discount | Coupon
+      type Discount {
+        id: ID!
+        name: String!
+      }
+      type Coupon {
+        id: ID!
+        name: String!
+      }
+    `),
+    {
+      importPath: '../types',
+      importNamespace: 'core',
+      encapsulate: 'none',
+      requireRootResolvers: false,
+      shouldDeclare: false,
+      rootTypes: ROOT_TYPES,
+      baseVisitor,
+      useGraphQLModules: true,
+    }
+  );
+
+  // User does not pick `__isTypeOf` because it is not a union member, or implementing types
+  expect(output).toBeSimilarStringTo(`
+    export type UserResolvers = Pick<core.UserResolvers, DefinedFields['User']>;
+  `);
+
+  // Cat picks `__isTypeOf` because it is an implementing type of Pet
+  expect(output).toBeSimilarStringTo(`
+    export type CatResolvers = Pick<core.CatResolvers, DefinedFields['Cat'] | '__isTypeOf'>;
+  `);
+  // Dog picks `__isTypeOf` because it is an implementing type of Pet
+  expect(output).toBeSimilarStringTo(`
+    export type DogResolvers = Pick<core.DogResolvers, DefinedFields['Dog'] | '__isTypeOf'>;
+  `);
+  // Elephant picks `__isTypeOf` because it is an implementing type of Pet, via `extend type `
+  expect(output).toBeSimilarStringTo(`
+    export type ElephantResolvers = Pick<core.ElephantResolvers, DefinedFields['Elephant'] | '__isTypeOf'>;
+  `);
+
+  // Discount picks `__isTypeOf` because it is a union member
+  expect(output).toBeSimilarStringTo(`
+    export type DiscountResolvers = Pick<core.DiscountResolvers, DefinedFields['Discount'] | '__isTypeOf'>;
+  `);
+  // Coupon picks `__isTypeOf` because it is a union member
+  expect(output).toBeSimilarStringTo(`
+    export type CouponResolvers = Pick<core.CouponResolvers, DefinedFields['Coupon'] | '__isTypeOf'>;
+  `);
+});