fix(mock): avoid double-wrapping null branch for required nullable scalars

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

@@ -209,6 +209,7 @@ export function getMockObject({
             Array.isArray(prop.type) && prop.type.includes('null');
           if (
             isNullable &&
+            !resolvedValue.nullWrapped &&
             !resolvedValue.overrided &&
             !mockOptions?.nonNullable
           ) {

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

@@ -143,9 +143,13 @@ export function getMockScalar({
     ),
   };
 
-  // OpenAPI 3.1 null unions only — 3.0 `nullable: true` is handled in object.ts
-  // to avoid double-wrapping scalar values that object.ts already null-randomizes.
+  // Both OpenAPI 3.1 `type: [..., 'null']` and OpenAPI 3.0 `nullable: true`
+  // reach here as a null union, because @scalar/openapi-parser upgrades 3.0
+  // inputs to 3.1 before mock generation. When this getter wraps the value via
+  // `getNullable` it flags the returned MockDefinition with `nullWrapped` so the
+  // object property layer does not add a second `arrayElement([..., null])`.
   const isNullable = Array.isArray(item.type) && item.type.includes('null');
+  const nullWrapped = isNullable && !nonNullableOption;
   // The @scalar/openapi-parser upgrader rewrites `format: binary` to
   // `contentMediaType: application/octet-stream` when upgrading OAS 3.0 → 3.1;
   // treat both equivalently so the mock emits the binary format value
@@ -161,6 +165,7 @@ export function getMockScalar({
       imports: [],
       name: item.name,
       overrided: false,
+      nullWrapped,
     };
   }
   if (item.format && ALL_FORMAT[item.format]) {
@@ -176,6 +181,7 @@ export function getMockScalar({
       imports: [],
       name: item.name,
       overrided: false,
+      nullWrapped,
     };
   }
 
@@ -249,6 +255,9 @@ export function getMockScalar({
         enums: item.enum,
         imports: numberImports,
         name: item.name,
+        // `item.enum` / `const` reassign `value` after `getNullable`, discarding
+        // the wrap — so only the plain numeric path is actually null-wrapped.
+        nullWrapped: nullWrapped && !item.enum && !('const' in item),
       };
     }
 
@@ -450,6 +459,7 @@ export function getMockScalar({
         enums: item.enum,
         name: item.name,
         imports: stringImports,
+        nullWrapped,
       };
     }
 

packages/mock/src/faker/resolvers/value.ts

@@ -359,6 +359,7 @@ export function resolveMockValue({
         imports,
         name: newSchema.name,
         type: getType(newSchema),
+        nullWrapped: Boolean(newSchema.nullable) && !mockOptions?.nonNullable,
       };
     }
 

packages/mock/src/types.ts

@@ -11,6 +11,10 @@ export interface MockDefinition {
   name: string;
   overrided?: boolean;
   includedProperties?: string[];
+  // True when `value` already embeds its own null branch (e.g. the scalar
+  // getter wrapped it via `getNullable`). The object property layer reads this
+  // to avoid wrapping the value in a second `arrayElement([..., null])`.
+  nullWrapped?: boolean;
 }
 
 type OpenApiObjectSchema = Extract<OpenApiSchemaObject, object>;

samples/angular-app/__snapshots__/api/endpoints-zod/pets/pets.msw.ts

@@ -39,10 +39,7 @@ export const getSearchPetsResponseMock = (): Pets =>
         undefined,
       ]))(),
     requiredNullableString: faker.helpers.arrayElement([
-      faker.helpers.arrayElement([
-        faker.string.alpha({ length: { min: 10, max: 20 } }),
-        null,
-      ]),
+      faker.string.alpha({ length: { min: 10, max: 20 } }),
       null,
     ]),
     optionalNullableString: faker.helpers.arrayElement([
@@ -83,10 +80,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -124,10 +118,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -186,10 +177,7 @@ export const getUpdatePetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -232,10 +220,7 @@ export const getPatchPetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([

samples/angular-app/__snapshots__/api/http-both/pets/pets.msw.ts

@@ -39,10 +39,7 @@ export const getSearchPetsResponseMock = (): Pets =>
         undefined,
       ]))(),
     requiredNullableString: faker.helpers.arrayElement([
-      faker.helpers.arrayElement([
-        faker.string.alpha({ length: { min: 10, max: 20 } }),
-        null,
-      ]),
+      faker.string.alpha({ length: { min: 10, max: 20 } }),
       null,
     ]),
     optionalNullableString: faker.helpers.arrayElement([
@@ -83,10 +80,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -124,10 +118,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -186,10 +177,7 @@ export const getUpdatePetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -232,10 +220,7 @@ export const getPatchPetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([

samples/angular-app/__snapshots__/api/http-client-custom-params/pets/pets.msw.ts

@@ -39,10 +39,7 @@ export const getSearchPetsResponseMock = (): Pets =>
         undefined,
       ]))(),
     requiredNullableString: faker.helpers.arrayElement([
-      faker.helpers.arrayElement([
-        faker.string.alpha({ length: { min: 10, max: 20 } }),
-        null,
-      ]),
+      faker.string.alpha({ length: { min: 10, max: 20 } }),
       null,
     ]),
     optionalNullableString: faker.helpers.arrayElement([
@@ -83,10 +80,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -124,10 +118,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -186,10 +177,7 @@ export const getUpdatePetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -232,10 +220,7 @@ export const getPatchPetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([

samples/angular-app/__snapshots__/api/http-client/pets/pets.msw.ts

@@ -39,10 +39,7 @@ export const getSearchPetsResponseMock = (): Pets =>
         undefined,
       ]))(),
     requiredNullableString: faker.helpers.arrayElement([
-      faker.helpers.arrayElement([
-        faker.string.alpha({ length: { min: 10, max: 20 } }),
-        null,
-      ]),
+      faker.string.alpha({ length: { min: 10, max: 20 } }),
       null,
     ]),
     optionalNullableString: faker.helpers.arrayElement([
@@ -83,10 +80,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -124,10 +118,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -186,10 +177,7 @@ export const getUpdatePetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -232,10 +220,7 @@ export const getPatchPetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([

samples/angular-app/__snapshots__/api/http-resource-zod/pets/pets.msw.ts

@@ -39,10 +39,7 @@ export const getSearchPetsResponseMock = (): Pets =>
         undefined,
       ]))(),
     requiredNullableString: faker.helpers.arrayElement([
-      faker.helpers.arrayElement([
-        faker.string.alpha({ length: { min: 10, max: 20 } }),
-        null,
-      ]),
+      faker.string.alpha({ length: { min: 10, max: 20 } }),
       null,
     ]),
     optionalNullableString: faker.helpers.arrayElement([
@@ -83,10 +80,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -124,10 +118,7 @@ export const getListPetsResponseMock = (): Pets =>
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -186,10 +177,7 @@ export const getUpdatePetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([
@@ -232,10 +220,7 @@ export const getPatchPetByIdResponseMock = (
           undefined,
         ]))(),
       requiredNullableString: faker.helpers.arrayElement([
-        faker.helpers.arrayElement([
-          faker.string.alpha({ length: { min: 10, max: 20 } }),
-          null,
-        ]),
+        faker.string.alpha({ length: { min: 10, max: 20 } }),
         null,
       ]),
       optionalNullableString: faker.helpers.arrayElement([