feat: support extensible enum values

src/services/__tests__/models/Schema.test.ts

@@ -311,6 +311,58 @@ describe('Models', () => {
       `);
     });
     describe('enum values', () => {
+      function createSchemaModel(schema: Record<string, unknown>) {
+        const parser = new OpenAPIParser(
+          {
+            openapi: '3.0.0',
+            info: { title: 'Enum extension test', version: '1.0.0' },
+            paths: {},
+          } as any,
+          undefined,
+          opts,
+        );
+        return new SchemaModel(parser, schema as any, '#/components/schemas/Test', opts);
+      }
+
+      test('uses x-extensible-enum values as display enums', () => {
+        const model = createSchemaModel({
+          type: 'string',
+          'x-extensible-enum': ['open', 'closed'],
+        });
+
+        expect(model.enum).toEqual(['open', 'closed']);
+        expect(printSchema(model, enumDetailsPrinter)).toContain('enum: [open,closed]');
+      });
+
+      test('uses other x-*-enum extension values', () => {
+        const model = createSchemaModel({
+          type: 'string',
+          'x-acme-status-enum': ['ready', 'closed'],
+        });
+
+        expect(model.enum).toEqual(['ready', 'closed']);
+        expect(printSchema(model, enumDetailsPrinter)).toContain('enum: [ready,closed]');
+      });
+
+      test('uses enum extensions declared on array items', () => {
+        const model = createSchemaModel({
+          type: 'array',
+          items: { type: 'string', 'x-extensible-enum': ['fast', 'slow'] },
+        });
+
+        expect(model.enum).toEqual(['fast', 'slow']);
+        expect(printSchema(model, enumDetailsPrinter)).toContain('enum: [fast,slow]');
+      });
+
+      test('prefers the standard enum when both forms are present', () => {
+        const model = createSchemaModel({
+          type: 'string',
+          enum: ['stable'],
+          'x-extensible-enum': ['preview'],
+        });
+
+        expect(model.enum).toEqual(['stable']);
+      });
       test('should get correct fields enum fields without duplication', () => {
         const spec = parseYaml(outdent`
           openapi: 3.0.0

src/services/models/Schema.ts

@@ -122,7 +122,7 @@ export class SchemaModel {
     this.description = schema.description || '';
     this.type = schema.type || detectType(schema);
     this.format = schema.format;
-    this.enum = schema.enum || [];
+    this.enum = getSchemaEnum(schema);
     this['x-enumDescriptions'] = schema['x-enumDescriptions'];
     this.example = schema.example;
     this.examples = schema.examples;
@@ -599,6 +599,20 @@ function buildAdditionalItems({
   return [];
 }
 
+function getSchemaEnum(schema: OpenAPISchema): any[] {
+  if (schema.enum !== undefined) {
+    return schema.enum;
+  }
+
+  const enumExtensions = Object.entries(schema).filter(
+    ([name, value]) => name.startsWith('x-') && name.endsWith('-enum') && Array.isArray(value),
+  );
+  const extensibleEnum = enumExtensions.find(([name]) => name === 'x-extensible-enum')?.[1];
+  const values = extensibleEnum ?? enumExtensions[0]?.[1];
+
+  return Array.isArray(values) ? values : [];
+}
+
 function getDiscriminator(schema: OpenAPISchema): OpenAPISchema['discriminator'] {
   return schema.discriminator || schema['x-discriminator'];
 }