fix(mock): emit boolean enum literals instead of random datatype.boolean() (#3428)

The MSW mock generator's boolean branch in scalar.ts ignored `item.enum`
and unconditionally emitted `faker.datatype.boolean()`. For schemas like
`oneOf [{ success: enum [true] }, { success: enum [false], failReason }]`
this broke the discriminator: the randomly-picked union variant set
`success` to a random boolean, so the mock no longer matched the
TypeScript literal type its branch enforced (`success: true` /
`success: false`).

Route boolean through the same `getEnum` helper as number/string so
`enum: [true]` emits `faker.helpers.arrayElement([true] as const)` and
`enum: [false]` likewise, keeping the mock value pinned to the chosen
branch's literal.

The type-generation half of #1775 was already addressed by #3159's
boolean-enum branch in `packages/core/src/getters/scalar.ts`; this
change closes the mock-side gap and adds a focused regression covering
the exact #1775 shape.

Closes #1775

Author: wadakatu

packages/mock/src/faker/getters/scalar.ts

@@ -240,12 +240,22 @@ export function getMockScalar({
 
     case 'boolean': {
       let value = 'faker.datatype.boolean()';
-      if ('const' in item) {
+      const booleanImports: GeneratorImport[] = [];
+      if (item.enum) {
+        value = getEnum(
+          item,
+          booleanImports,
+          context,
+          existingReferencedProperties,
+          'boolean',
+        );
+      } else if ('const' in item) {
         value = JSON.stringify(item.const);
       }
       return {
         value,
-        imports: [],
+        enums: item.enum,
+        imports: booleanImports,
         name: item.name,
       };
     }
@@ -463,7 +473,7 @@ function getEnum(
   imports: GeneratorImport[],
   context: ContextSpec,
   existingReferencedProperties: string[],
-  type?: 'string' | 'number',
+  type?: 'string' | 'number' | 'boolean',
 ) {
   if (!item.enum) return '';
   const joinedEnumValues = item.enum

tests/__snapshots__/default/issue-1775/endpoints.ts

@@ -0,0 +1,63 @@
+/**
+ * Generated by orval v8.12.3 🍺
+ * Do not edit manually.
+ * issue-1775
+ * OpenAPI spec version: 1.0.0
+ */
+import axios from 'axios';
+import type { AxiosRequestConfig, AxiosResponse } from 'axios';
+
+import type { PutApiOrderLimit200Item } from './model';
+
+import { faker } from '@faker-js/faker';
+
+import { HttpResponse, http } from 'msw';
+import type { RequestHandlerOptions } from 'msw';
+
+export const putApiOrderLimit = (
+  options?: AxiosRequestConfig,
+): Promise<AxiosResponse<PutApiOrderLimit200Item[]>> => {
+  return axios.put(`/api/order/limit`, undefined, options);
+};
+
+export type PutApiOrderLimitResult = AxiosResponse<PutApiOrderLimit200Item[]>;
+
+export const getPutApiOrderLimitResponseMock = (): PutApiOrderLimit200Item[] =>
+  Array.from(
+    { length: faker.number.int({ min: 1, max: 10 }) },
+    (_, i) => i + 1,
+  ).map(() => ({
+    ...{ orderId: faker.string.alpha({ length: { min: 10, max: 20 } }) },
+    ...faker.helpers.arrayElement([
+      { success: faker.helpers.arrayElement([true] as const) },
+      {
+        success: faker.helpers.arrayElement([false] as const),
+        failReason: faker.string.alpha({ length: { min: 10, max: 20 } }),
+      },
+    ]),
+  }));
+
+export const getPutApiOrderLimitMockHandler = (
+  overrideResponse?:
+    | PutApiOrderLimit200Item[]
+    | ((
+        info: Parameters<Parameters<typeof http.put>[1]>[0],
+      ) => Promise<PutApiOrderLimit200Item[]> | PutApiOrderLimit200Item[]),
+  options?: RequestHandlerOptions,
+) => {
+  return http.put(
+    '*/api/order/limit',
+    async (info: Parameters<Parameters<typeof http.put>[1]>[0]) => {
+      return HttpResponse.json(
+        overrideResponse !== undefined
+          ? typeof overrideResponse === 'function'
+            ? await overrideResponse(info)
+            : overrideResponse
+          : getPutApiOrderLimitResponseMock(),
+        { status: 200 },
+      );
+    },
+    options,
+  );
+};
+export const getIssue1775Mock = () => [getPutApiOrderLimitMockHandler()];

tests/__snapshots__/default/issue-1775/model/index.ts

@@ -0,0 +1,8 @@
+/**
+ * Generated by orval v8.12.3 🍺
+ * Do not edit manually.
+ * issue-1775
+ * OpenAPI spec version: 1.0.0
+ */
+
+export * from './putApiOrderLimit200Item';

tests/__snapshots__/default/issue-1775/model/putApiOrderLimit200Item.ts

@@ -0,0 +1,18 @@
+/**
+ * Generated by orval v8.12.3 🍺
+ * Do not edit manually.
+ * issue-1775
+ * OpenAPI spec version: 1.0.0
+ */
+
+export type PutApiOrderLimit200Item = (
+  | {
+      success: true;
+    }
+  | {
+      success: false;
+      failReason: string;
+    }
+) & {
+  orderId: string;
+};

tests/__snapshots__/default/nullable-oneof-enums/endpoints.ts

@@ -90,7 +90,7 @@ export const getGetItemsWithMultiplePropsResponseMock = (): Item3[] =>
     world: faker.helpers.arrayElement([
       faker.helpers.arrayElement([
         faker.helpers.arrayElement([1, 2, 3] as const),
-        faker.datatype.boolean(),
+        faker.helpers.arrayElement([true, false] as const),
       ]),
       null,
     ]),
@@ -121,7 +121,7 @@ export const getGetNestedItemsResponseMock = (): NestedItem[] =>
         world: faker.helpers.arrayElement([
           faker.helpers.arrayElement([
             faker.helpers.arrayElement([1, 2, 3] as const),
-            faker.datatype.boolean(),
+            faker.helpers.arrayElement([true, false] as const),
           ]),
           null,
         ]),
@@ -173,8 +173,8 @@ export const getGetMixedTypeEnumsResponseMock = (): MixedTypeEnums[] =>
     ]),
     booleanEnum: faker.helpers.arrayElement([
       faker.helpers.arrayElement([
-        faker.datatype.boolean(),
-        faker.datatype.boolean(),
+        faker.helpers.arrayElement([true, false] as const),
+        faker.helpers.arrayElement([true] as const),
       ]),
       null,
     ]),

tests/api-generation.spec.ts

@@ -476,3 +476,42 @@ test('fetch issue-1879 inlines header schema when $ref targets another path para
   );
   expect(indexContent).not.toMatch(/\bn0\b/);
 });
+
+test('default issue-1775 preserves boolean enum literals across allOf+oneOf', async () => {
+  // Regression for #1775: an `allOf: [{orderId}, oneOf: [{success: enum [true]},
+  // {success: enum [false], failReason}]]` schema returned as an array.
+  //
+  // The type-generation half (boolean-literal preservation) was already fixed
+  // by #3159's enum branch in `packages/core/src/getters/scalar.ts`. The mock
+  // half is what this regression locks down: the boolean branch in
+  // `packages/mock/src/faker/getters/scalar.ts` previously ignored `item.enum`
+  // and unconditionally emitted `faker.datatype.boolean()`, so each `oneOf`
+  // variant's `success` randomly flipped instead of matching its literal type.
+  // The fix routes boolean through the same `getEnum` helper as number/string,
+  // emitting `faker.helpers.arrayElement([true] as const)` /
+  // `arrayElement([false] as const)` so the mock's discriminator stays in sync
+  // with the union branch it picked.
+  const model = await readFile(
+    generated('default', 'issue-1775', 'model', 'putApiOrderLimit200Item.ts'),
+    'utf8',
+  );
+
+  // The two oneOf branches keep their literal types, and `orderId` is shared
+  // through the `& { orderId: string }` half of the allOf intersection.
+  expect(model).toContain('success: true;');
+  expect(model).toContain('success: false;');
+  expect(model).toContain('failReason: string;');
+  expect(model).toContain('orderId: string;');
+
+  const endpoints = await readFile(
+    generated('default', 'issue-1775', 'endpoints.ts'),
+    'utf8',
+  );
+
+  // Each oneOf branch's mock must pin `success` to the branch's literal so a
+  // random selection still produces a valid `PutApiOrderLimit200Item`. The
+  // pre-fix output emitted `faker.datatype.boolean()` for both branches.
+  expect(endpoints).toContain('arrayElement([true] as const)');
+  expect(endpoints).toContain('arrayElement([false] as const)');
+  expect(endpoints).not.toMatch(/success: faker\.datatype\.boolean\(\)/);
+});

tests/configs/default.config.ts

@@ -129,6 +129,16 @@ export default defineConfig({
       formatter: 'prettier',
     },
   },
+  'issue-1775': {
+    input: '../specifications/issue-1775.yaml',
+    output: {
+      schemas: '../generated/default/issue-1775/model',
+      target: '../generated/default/issue-1775/endpoints.ts',
+      mock: true,
+      clean: true,
+      formatter: 'prettier',
+    },
+  },
   'all-of-without-type': {
     input: '../specifications/all-of-without-type.yaml',
     output: {

tests/specifications/issue-1775.yaml

@@ -0,0 +1,43 @@
+openapi: 3.0.1
+info:
+  version: 1.0.0
+  title: issue-1775
+paths:
+  /api/order/limit:
+    put:
+      operationId: putApiOrderLimit
+      responses:
+        '200':
+          description: Batch result
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  allOf:
+                    - type: object
+                      required:
+                        - orderId
+                      properties:
+                        orderId:
+                          type: string
+                    - oneOf:
+                        - type: object
+                          required:
+                            - success
+                          properties:
+                            success:
+                              type: boolean
+                              enum:
+                                - true
+                        - type: object
+                          required:
+                            - success
+                            - failReason
+                          properties:
+                            success:
+                              type: boolean
+                              enum:
+                                - false
+                            failReason:
+                              type: string