Add mock generator util tests

scripts/__mocks__/@pdfme/generator.test.ts

@@ -0,0 +1,18 @@
+import { generate } from './generator';
+
+describe('Testing mock generate util', () => {
+  test('should return a Promise', async () => {
+    const result = generate();
+    expect(result).toBeInstanceOf(Promise);
+  });
+
+  test('should resolve to a Uint8Array', async () => {
+    const result = await generate();
+    expect(result).toBeInstanceOf(Uint8Array);
+  });
+
+  test('should resolve to a Uint8Array with correct values', async () => {
+    const result = await generate();
+    expect(result).toEqual(new Uint8Array([10, 20, 30, 40, 50]));
+  });
+});