From 6ed53b35bc202284b29eed0f925de798a56994a6 Mon Sep 17 00:00:00 2001
From: Jeff Lewis <mail@jeffreylewis.me>
Date: Wed, 17 Apr 2019 14:32:30 -0500
Subject: [PATCH] Add __typename to TS and Flow types

---
 packages/plugins/flow/flow/tests/flow.spec.ts |  65 ++++++++++++
 .../src/base-documents-visitor.ts             |  17 +--
 .../src/base-resolvers-visitor.ts             |   5 +-
 .../src/base-types-visitor.ts                 |  20 +++-
 .../visitor-plugin-common/src/base-visitor.ts |  17 +++
 .../other/visitor-plugin-common/src/utils.ts  |  13 ++-
 .../typescript/tests/typescript.spec.ts       | 100 ++++++++++++++++++
 7 files changed, 215 insertions(+), 22 deletions(-)

diff --git a/packages/plugins/flow/flow/tests/flow.spec.ts b/packages/plugins/flow/flow/tests/flow.spec.ts
index 9cae14ace4a..5bf0e4ebf77 100644
--- a/packages/plugins/flow/flow/tests/flow.spec.ts
+++ b/packages/plugins/flow/flow/tests/flow.spec.ts
@@ -217,6 +217,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type B = {
+        __typename?: "B",
         /** the id */
         id?: ?$ElementType<Scalars, 'ID'>,
       };`);
@@ -235,6 +236,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type Node = {
+        __typename?: "Node",
         /** the id */
         id: $ElementType<Scalars, 'ID'>,
       };`);
@@ -298,6 +300,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {|
+          __typename?: "MyInterface",
           foo?: ?$ElementType<Scalars, 'String'>,
           bar: $ElementType<Scalars, 'String'>,
         |};
@@ -322,6 +325,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           +foo?: ?$ElementType<Scalars, 'String'>,
           +bar: $ElementType<Scalars, 'String'>,
         };
@@ -354,6 +358,7 @@ describe('Flow Plugin', () => {
     `);
       expect(result).toBeSimilarStringTo(`
         export type mytype = {
+          __typename?: "MyType",
           foo?: ?$ElementType<Scalars, 'String'>,
         };
     `);
@@ -397,6 +402,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type Imytype = {
+          __typename?: "MyType",
           foo?: ?$ElementType<Scalars, 'String'>,
         };
       `);
@@ -459,6 +465,7 @@ describe('Flow Plugin', () => {
       expect(result).toBeSimilarStringTo(`export type myenum = $Values<typeof myenumvalues>;`);
 
       expect(result).toBeSimilarStringTo(`export type mytype = {
+          __typename?: "MyType",
           f?: ?$ElementType<Scalars, 'String'>,
           bar?: ?myenum,
           b_a_r?: ?$ElementType<Scalars, 'String'>,
@@ -466,28 +473,34 @@ describe('Flow Plugin', () => {
         };`);
 
       expect(result).toBeSimilarStringTo(`export type my_type = {
+          __typename?: "My_Type",
           linkTest?: ?mytype,
         };`);
 
       expect(result).toBeSimilarStringTo(`export type myunion = my_type | mytype;`);
 
       expect(result).toBeSimilarStringTo(`export type some_interface = {
+          __typename?: "Some_Interface",
           id: $ElementType<Scalars, 'ID'>,
         };`);
 
       expect(result).toBeSimilarStringTo(`export type impl1 = some_interface & {
+          __typename?: "Impl1",
           id: $ElementType<Scalars, 'ID'>,
         };`);
 
       expect(result).toBeSimilarStringTo(`export type impl_2 = some_interface & {
+          __typename?: "Impl_2",
           id: $ElementType<Scalars, 'ID'>,
         };`);
 
       expect(result).toBeSimilarStringTo(`export type impl_3 = some_interface & {
+          __typename?: "impl_3",
           id: $ElementType<Scalars, 'ID'>,
         };`);
 
       expect(result).toBeSimilarStringTo(`export type query = {
+          __typename?: "Query",
           something?: ?myunion,
           use_interface?: ?some_interface,
         };`);
@@ -508,6 +521,7 @@ describe('Flow Plugin', () => {
       expect(result).toBeSimilarStringTo(`export type MyEnum = $Values<typeof MyEnumValues>;`);
 
       expect(result).toBeSimilarStringTo(`export type MyType = {
+        __typename?: "MyType",
         f?: ?$ElementType<Scalars, 'String'>,
         bar?: ?MyEnum,
         b_a_r?: ?$ElementType<Scalars, 'String'>,
@@ -515,28 +529,34 @@ describe('Flow Plugin', () => {
       };`);
 
       expect(result).toBeSimilarStringTo(`export type My_Type = {
+        __typename?: "My_Type",
         linkTest?: ?MyType,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type MyUnion = My_Type | MyType;`);
 
       expect(result).toBeSimilarStringTo(`export type Some_Interface = {
+        __typename?: "Some_Interface",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type Impl1 = Some_Interface & {
+        __typename?: "Impl1",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type Impl_2 = Some_Interface & {
+        __typename?: "Impl_2",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type Impl_3 = Some_Interface & {
+        __typename?: "impl_3",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type Query = {
+        __typename?: "Query",
         something?: ?MyUnion,
         use_interface?: ?Some_Interface,
       };`);
@@ -556,6 +576,7 @@ describe('Flow Plugin', () => {
       expect(result).toBeSimilarStringTo(`export type IMyEnum = $Values<typeof IMyEnumValues>;`);
 
       expect(result).toBeSimilarStringTo(`export type IMyType = {
+        __typename?: "MyType",
         f?: ?$ElementType<Scalars, 'String'>,
         bar?: ?IMyEnum,
         b_a_r?: ?$ElementType<Scalars, 'String'>,
@@ -563,28 +584,34 @@ describe('Flow Plugin', () => {
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IMy_Type = {
+        __typename?: "My_Type",
         linkTest?: ?IMyType,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IMyUnion = IMy_Type | IMyType;`);
 
       expect(result).toBeSimilarStringTo(`export type ISome_Interface = {
+        __typename?: "Some_Interface",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IImpl1 = ISome_Interface & {
+        __typename?: "Impl1",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IImpl_2 = ISome_Interface & {
+        __typename?: "Impl_2",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IImpl_3 = ISome_Interface & {
+        __typename?: "impl_3",
         id: $ElementType<Scalars, 'ID'>,
       };`);
 
       expect(result).toBeSimilarStringTo(`export type IQuery = {
+        __typename?: "Query",
         something?: ?IMyUnion,
         use_interface?: ?ISome_Interface,
       };`);
@@ -654,6 +681,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type TMutation = {
+          __typename?: "Mutation",
           foo?: ?$ElementType<Scalars, 'String'>,
         };
 
@@ -819,6 +847,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo?: ?$ElementType<Scalars, 'String'>,
           bar: $ElementType<Scalars, 'String'>,
         };
@@ -840,11 +869,13 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo: $ElementType<Scalars, 'String'>,
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyType = MyInterface & {
+          __typename?: "MyType",
           foo: $ElementType<Scalars, 'String'>,
         };
       `);
@@ -870,16 +901,19 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo: $ElementType<Scalars, 'String'>,
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyOtherInterface = {
+          __typename?: "MyOtherInterface",
           bar: $ElementType<Scalars, 'String'>,
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyType = MyInterface & MyOtherInterface & {
+          __typename?: "MyType",
           foo: $ElementType<Scalars, 'String'>,
           bar: $ElementType<Scalars, 'String'>,
         };
@@ -901,11 +935,13 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo: MyOtherType,
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyOtherType = {
+          __typename?: "MyOtherType",
           bar: $ElementType<Scalars, 'String'>,
         };
       `);
@@ -947,6 +983,7 @@ describe('Flow Plugin', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo?: ?$ElementType<Scalars, 'String'>,
           bar: $ElementType<Scalars, 'String'>,
         };
@@ -1003,4 +1040,32 @@ describe('Flow Plugin', () => {
       validateFlow(result);
     });
   });
+
+  it('should not contain __typename', async () => {
+    const schema = buildSchema(/* GraphQL */ `
+      type User {
+        id: Int!
+        name: String!
+        email: String!
+      }
+      type QueryRoot {
+        allUsers: [User]!
+        userById(id: Int!): User
+        # Generates a new answer for the guessing game
+        answer: [Int!]!
+      }
+      type SubscriptionRoot {
+        newUser: User
+      }
+      schema {
+        query: QueryRoot
+        subscription: SubscriptionRoot
+      }
+    `);
+
+    const content = await plugin(schema, [], { skipTypename: true }, { outputFile: '' });
+    expect(content).not.toContain('__typename');
+
+    validateFlow(content);
+  });
 });
diff --git a/packages/plugins/other/visitor-plugin-common/src/base-documents-visitor.ts b/packages/plugins/other/visitor-plugin-common/src/base-documents-visitor.ts
index 522505b3746..985f7506719 100644
--- a/packages/plugins/other/visitor-plugin-common/src/base-documents-visitor.ts
+++ b/packages/plugins/other/visitor-plugin-common/src/base-documents-visitor.ts
@@ -22,22 +22,7 @@ export interface ParsedDocumentsConfig extends ParsedConfig {
   addTypename: boolean;
 }
 
-export interface RawDocumentsConfig extends RawConfig {
-  /**
-   * @name skipTypename
-   * @type boolean
-   * @default false
-   * @description Automatically adds `__typename` field to the generated types, even when they are not specified
-   * in the selection set.
-   *
-   * @example
-   * ```yml
-   * config:
-   *   skipTypename: true
-   * ```
-   */
-  skipTypename?: boolean;
-}
+export interface RawDocumentsConfig extends RawConfig {}
 
 export class BaseDocumentsVisitor<TRawConfig extends RawDocumentsConfig = RawDocumentsConfig, TPluginConfig extends ParsedDocumentsConfig = ParsedDocumentsConfig> extends BaseVisitor<TRawConfig, TPluginConfig> {
   protected _unnamedCounter = 1;
diff --git a/packages/plugins/other/visitor-plugin-common/src/base-resolvers-visitor.ts b/packages/plugins/other/visitor-plugin-common/src/base-resolvers-visitor.ts
index 9e3375764d3..ef5a4b738ea 100644
--- a/packages/plugins/other/visitor-plugin-common/src/base-resolvers-visitor.ts
+++ b/packages/plugins/other/visitor-plugin-common/src/base-resolvers-visitor.ts
@@ -267,7 +267,10 @@ export class BaseResolversVisitor<TRawConfig extends RawResolversConfig = RawRes
   }
 
   protected replaceFieldsInType(typeName: string, relevantFields: { fieldName: string; replaceWithType: string }[]): string {
-    return `Omit<${typeName}, ${relevantFields.map(f => `'${f.fieldName}'`).join(' | ')}> & { ${relevantFields.map(f => `${f.fieldName}: ${f.replaceWithType}`).join(', ')} }`;
+    const omitFields = relevantFields.map(f => `'${f.fieldName}'`).join(' | ');
+    const keepFields = relevantFields.map(f => `${f.fieldName}: ${f.replaceWithType}`).join(', ');
+
+    return `Omit<${typeName}, ${omitFields}> & { ${keepFields} }`;
   }
 
   protected applyMaybe(str: string): string {
diff --git a/packages/plugins/other/visitor-plugin-common/src/base-types-visitor.ts b/packages/plugins/other/visitor-plugin-common/src/base-types-visitor.ts
index 797263043f6..92ad15e0020 100644
--- a/packages/plugins/other/visitor-plugin-common/src/base-types-visitor.ts
+++ b/packages/plugins/other/visitor-plugin-common/src/base-types-visitor.ts
@@ -15,6 +15,8 @@ import {
   ScalarTypeDefinitionNode,
   UnionTypeDefinitionNode,
   StringValueNode,
+  isUnionType,
+  isInterfaceType,
 } from 'graphql';
 import { BaseVisitor, ParsedConfig, RawConfig } from './base-visitor';
 import { parseMapper } from './mappers';
@@ -141,13 +143,18 @@ export class BaseTypesVisitor<TRawConfig extends RawTypesConfig = RawTypesConfig
     const originalNode = parent[key] as ObjectTypeDefinitionNode;
     const interfaces = originalNode.interfaces && node.interfaces.length > 0 ? originalNode.interfaces.map(i => this.convertName(i)).join(' & ') + (node.fields.length ? ' & ' : '') : '';
 
-    const typeDefinition = new DeclarationBlock(this._declarationBlockConfig)
+    let declarationBlock = new DeclarationBlock(this._declarationBlockConfig)
       .export()
       .asKind('type')
       .withName(this.convertName(node))
       .withContent(interfaces)
       .withComment((node.description as any) as string)
-      .withBlock(node.fields.join('\n')).string;
+      .withComment((node.description as any) as string);
+
+    if (this._parsedConfig.addTypename) {
+      declarationBlock = declarationBlock.withTypeName(node.name);
+    }
+    const typeDefinition = declarationBlock.withBlock(node.fields.join('\n')).string;
 
     const argumentsBlock = this.buildArgumentsBlock(originalNode);
 
@@ -157,12 +164,17 @@ export class BaseTypesVisitor<TRawConfig extends RawTypesConfig = RawTypesConfig
   InterfaceTypeDefinition(node: InterfaceTypeDefinitionNode, key: number | string, parent: any): string {
     const argumentsBlock = this.buildArgumentsBlock(parent[key] as InterfaceTypeDefinitionNode);
 
-    const interfaceDefinition = new DeclarationBlock(this._declarationBlockConfig)
+    let declarationBlock = new DeclarationBlock(this._declarationBlockConfig)
       .export()
       .asKind('type')
       .withName(this.convertName(node))
       .withComment((node.description as any) as string)
-      .withBlock(node.fields.join('\n')).string;
+      .withComment((node.description as any) as string);
+
+    if (this._parsedConfig.addTypename) {
+      declarationBlock = declarationBlock.withTypeName(node.name);
+    }
+    const interfaceDefinition = declarationBlock.withBlock(node.fields.join('\n')).string;
 
     return [interfaceDefinition, argumentsBlock].filter(f => f).join('\n\n');
   }
diff --git a/packages/plugins/other/visitor-plugin-common/src/base-visitor.ts b/packages/plugins/other/visitor-plugin-common/src/base-visitor.ts
index de2a0f1e4d7..4fd497d0e96 100644
--- a/packages/plugins/other/visitor-plugin-common/src/base-visitor.ts
+++ b/packages/plugins/other/visitor-plugin-common/src/base-visitor.ts
@@ -13,6 +13,7 @@ export interface ParsedConfig {
   scalars: ScalarsMap;
   convert: ConvertFn;
   typesPrefix: string;
+  addTypename: boolean;
 }
 
 export interface RawConfig {
@@ -72,6 +73,21 @@ export interface RawConfig {
    * ```
    */
   typesPrefix?: string;
+
+  /**
+   * @name skipTypename
+   * @type boolean
+   * @default false
+   * @description Automatically adds `__typename` field to the generated types, even when they are not specified
+   * in the selection set.
+   *
+   * @example
+   * ```yml
+   * config:
+   *   skipTypename: true
+   * ```
+   */
+  skipTypename?: boolean;
 }
 
 export class BaseVisitor<TRawConfig extends RawConfig = RawConfig, TPluginConfig extends ParsedConfig = ParsedConfig> {
@@ -83,6 +99,7 @@ export class BaseVisitor<TRawConfig extends RawConfig = RawConfig, TPluginConfig
       scalars: { ...(defaultScalars || DEFAULT_SCALARS), ...(rawConfig.scalars || {}) },
       convert: convertFactory(rawConfig),
       typesPrefix: rawConfig.typesPrefix || '',
+      addTypename: !rawConfig.skipTypename,
       ...((additionalConfig || {}) as any),
     };
 
diff --git a/packages/plugins/other/visitor-plugin-common/src/utils.ts b/packages/plugins/other/visitor-plugin-common/src/utils.ts
index e7f3ac2ec58..0cde98b6f63 100644
--- a/packages/plugins/other/visitor-plugin-common/src/utils.ts
+++ b/packages/plugins/other/visitor-plugin-common/src/utils.ts
@@ -113,6 +113,7 @@ export class DeclarationBlock {
   _nameGenerics = null;
   _comment = null;
   _ignoreBlockWrapper = false;
+  _typeName = null;
 
   constructor(private _config: DeclarationBlockConfig) {
     this._config = {
@@ -169,6 +170,12 @@ export class DeclarationBlock {
     return this;
   }
 
+  withTypeName(typeName: NameNode) {
+    this._typeName = typeName;
+
+    return this;
+  }
+
   public get string(): string {
     let result = '';
 
@@ -199,7 +206,7 @@ export class DeclarationBlock {
       const blockWrapper = this._ignoreBlockWrapper ? '' : this._config.blockWrapper;
       const before = '{' + blockWrapper;
       const after = blockWrapper + '}';
-      const block = [before, this._block, after].join('\n');
+      const block = [before, buildTypeName(this._typeName), this._block, after].filter(val => !!val).join('\n');
 
       if (this._methodName) {
         result += `${this._methodName}(${this._config.blockTransformer!(block)})`;
@@ -216,6 +223,10 @@ export class DeclarationBlock {
   }
 }
 
+function buildTypeName(name: NameNode | null): string | null {
+  return name ? indent(`__typename?: "${name}",`) : null;
+}
+
 export function getBaseTypeNode(typeNode: TypeNode): NamedTypeNode {
   if (typeNode.kind === Kind.LIST_TYPE || typeNode.kind === Kind.NON_NULL_TYPE) {
     return getBaseTypeNode(typeNode.type);
diff --git a/packages/plugins/typescript/typescript/tests/typescript.spec.ts b/packages/plugins/typescript/typescript/tests/typescript.spec.ts
index 1a6fbe8574e..7598ee41551 100644
--- a/packages/plugins/typescript/typescript/tests/typescript.spec.ts
+++ b/packages/plugins/typescript/typescript/tests/typescript.spec.ts
@@ -137,6 +137,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type B = {
+        __typename?: "B",
         /** the id */
         id?: Maybe<Scalars['ID']>,
       };`);
@@ -153,6 +154,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type Node = {
+        __typename?: "Node",
         /** the id */
         id: Scalars['ID'],
       };`);
@@ -254,6 +256,7 @@ describe('TypeScript', () => {
       expect(result).toBeSimilarStringTo(`export type Any = Scalars['String'] | Scalars['Int'] | Scalars['Float'] | Scalars['ID'];`);
       expect(result).toBeSimilarStringTo(`
       export type CardEdge = {
+        __typename?: "CardEdge",
         count: Scalars['Int'],
       };`);
       validateTs(result);
@@ -271,6 +274,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo: Maybe<Scalars['String']>,
           bar: Scalars['String'],
         };
@@ -287,6 +291,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           readonly foo: ReadonlyArray<Scalars['String']>,
         };
       `);
@@ -375,6 +380,7 @@ describe('TypeScript', () => {
     `);
       expect(result).toBeSimilarStringTo(`
         export type mytype = {
+          __typename?: "MyType",
           foo?: Maybe<foo>,
         };
     `);
@@ -450,6 +456,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo?: Maybe<Foo>,
         };
       `);
@@ -534,6 +541,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type MyType = {
+        __typename?: "MyType",
         foo?: Maybe<Scalars['String']>,
         bar: Scalars['String'],
       };`);
@@ -562,6 +570,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type MyType = {
+        __typename?: "MyType",
         foo?: Maybe<Scalars['String']>,
         bar: Scalars['MyScalar'],
       };`);
@@ -590,6 +599,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type MyType = {
+        __typename?: "MyType",
         foo?: Maybe<Scalars['String']>,
         bar: Scalars['MyScalar'],
       };`);
@@ -608,6 +618,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo?: Maybe<Scalars['String']>,
           bar: Scalars['String'],
         };
@@ -629,11 +640,13 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo: Scalars['String'],
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyType = MyInterface & {
+          __typename?: "MyType",
           foo: Scalars['String'],
         };
       `);
@@ -659,16 +672,19 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo: Scalars['String'],
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyOtherInterface = {
+          __typename?: "MyOtherInterface",
           bar: Scalars['String'],
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyType = MyInterface & MyOtherInterface & {
+          __typename?: "MyType",
           foo: Scalars['String'],
           bar: Scalars['String'],
         };
@@ -688,6 +704,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo: Scalars['String'],
         };
       `);
@@ -711,11 +728,13 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyType = {
+          __typename?: "MyType",
           foo: MyOtherType,
         };
       `);
       expect(result).toBeSimilarStringTo(`
         export type MyOtherType = {
+          __typename?: "MyOtherType",
           bar: Scalars['String'],
         };
       `);
@@ -756,6 +775,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type MyInterface = {
+          __typename?: "MyInterface",
           foo?: Maybe<Scalars['String']>,
           bar: Scalars['String'],
         };
@@ -798,6 +818,7 @@ describe('TypeScript', () => {
     `);
       expect(result).toBeSimilarStringTo(`
         export type mytype = {
+          __typename?: "MyType",
           foo?: Maybe<Scalars['String']>,
         };
     `);
@@ -820,6 +841,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type Imytype = {
+          __typename?: "MyType",
           foo?: Maybe<Scalars['String']>,
         };
       `);
@@ -881,6 +903,7 @@ describe('TypeScript', () => {
         `);
       expect(result).toBeSimilarStringTo(`
         export type mytype = {
+          __typename?: "MyType",
           f?: Maybe<Scalars['String']>,
           bar?: Maybe<myenum>,
           b_a_r?: Maybe<Scalars['String']>,
@@ -889,6 +912,7 @@ describe('TypeScript', () => {
         `);
       expect(result).toBeSimilarStringTo(`
         export type my_type = {
+          __typename?: "My_Type",
           linkTest?: Maybe<mytype>,
         };
         `);
@@ -897,26 +921,31 @@ describe('TypeScript', () => {
         `);
       expect(result).toBeSimilarStringTo(`
         export type some_interface = {
+          __typename?: "Some_Interface",
           id: Scalars['ID'],
         };
         `);
       expect(result).toBeSimilarStringTo(`
         export type impl1 = some_interface & {
+          __typename?: "Impl1",
           id: Scalars['ID'],
         };
         `);
       expect(result).toBeSimilarStringTo(`
         export type impl_2 = some_interface & {
+          __typename?: "Impl_2",
           id: Scalars['ID'],
         };
         `);
       expect(result).toBeSimilarStringTo(`
         export type impl_3 = some_interface & {
+          __typename?: "impl_3",
           id: Scalars['ID'],
         };
         `);
       expect(result).toBeSimilarStringTo(`
         export type query = {
+          __typename?: "Query",
           something?: Maybe<myunion>,
           use_interface?: Maybe<some_interface>,
         };
@@ -937,6 +966,7 @@ describe('TypeScript', () => {
       `);
       expect(result).toBeSimilarStringTo(`
       export type MyType = {
+        __typename?: "MyType",
         f?: Maybe<Scalars['String']>,
         bar?: Maybe<MyEnum>,
         b_a_r?: Maybe<Scalars['String']>,
@@ -945,6 +975,7 @@ describe('TypeScript', () => {
       `);
       expect(result).toBeSimilarStringTo(`
       export type My_Type = {
+        __typename?: "My_Type",
         linkTest?: Maybe<MyType>,
       };
       `);
@@ -953,26 +984,31 @@ describe('TypeScript', () => {
       `);
       expect(result).toBeSimilarStringTo(`
       export type Some_Interface = {
+        __typename?: "Some_Interface",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type Impl1 = Some_Interface & {
+        __typename?: "Impl1",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type Impl_2 = Some_Interface & {
+        __typename?: "Impl_2",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type Impl_3 = Some_Interface & {
+        __typename?: "impl_3",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type Query = {
+        __typename?: "Query",
         something?: Maybe<MyUnion>,
         use_interface?: Maybe<Some_Interface>,
       };
@@ -993,6 +1029,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
       export type IMyType = {
+        __typename?: "MyType",
         f?: Maybe<Scalars['String']>,
         bar?: Maybe<IMyEnum>,
         b_a_r?: Maybe<Scalars['String']>,
@@ -1000,32 +1037,38 @@ describe('TypeScript', () => {
       };`);
       expect(result).toBeSimilarStringTo(`
       export type IMy_Type = {
+        __typename?: "My_Type",
         linkTest?: Maybe<IMyType>,
       };
   `);
       expect(result).toBeSimilarStringTo(`export type IMyUnion = IMy_Type | IMyType;`);
       expect(result).toBeSimilarStringTo(`
       export type ISome_Interface = {
+        __typename?: "Some_Interface",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type IImpl1 = ISome_Interface & {
+        __typename?: "Impl1",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type IImpl_2 = ISome_Interface & {
+        __typename?: "Impl_2",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type IImpl_3 = ISome_Interface & {
+        __typename?: "impl_3",
         id: Scalars['ID'],
       };
       `);
       expect(result).toBeSimilarStringTo(`
       export type IQuery = {
+        __typename?: "Query",
         something?: Maybe<IMyUnion>,
         use_interface?: Maybe<ISome_Interface>,
       };
@@ -1097,6 +1140,7 @@ describe('TypeScript', () => {
 
       expect(result).toBeSimilarStringTo(`
         export type TMutation = {
+          __typename?: "Mutation",
           foo?: Maybe<Scalars['String']>,
         };
 
@@ -1220,4 +1264,60 @@ describe('TypeScript', () => {
 
     validateTs(content);
   });
+
+  it('should contain __typename', async () => {
+    const schema = buildSchema(/* GraphQL */ `
+      type User {
+        id: Int!
+        name: String!
+        email: String!
+      }
+      type QueryRoot {
+        allUsers: [User]!
+        userById(id: Int!): User
+        # Generates a new answer for the guessing game
+        answer: [Int!]!
+      }
+      type SubscriptionRoot {
+        newUser: User
+      }
+      schema {
+        query: QueryRoot
+        subscription: SubscriptionRoot
+      }
+    `);
+
+    const content = await plugin(schema, [], {}, { outputFile: '' });
+    expect(content).toContain('__typename');
+
+    validateTs(content);
+  });
+
+  it('should not contain __typename', async () => {
+    const schema = buildSchema(/* GraphQL */ `
+      type User {
+        id: Int!
+        name: String!
+        email: String!
+      }
+      type QueryRoot {
+        allUsers: [User]!
+        userById(id: Int!): User
+        # Generates a new answer for the guessing game
+        answer: [Int!]!
+      }
+      type SubscriptionRoot {
+        newUser: User
+      }
+      schema {
+        query: QueryRoot
+        subscription: SubscriptionRoot
+      }
+    `);
+
+    const content = await plugin(schema, [], { skipTypename: true }, { outputFile: '' });
+    expect(content).not.toContain('__typename');
+
+    validateTs(content);
+  });
 });