Example on how to better organize your test using Jest

person.spec.ts

describe('Person', () => {
  describe('#setName', () => {
    it('should set name when name is passed', () => {
      const person = new Person();
      const name = 'Alex';
      
      person.setName(name);

      expect(person.name).toBe(name);
    });
  });
});

person.ts

export class Person {
  age: number;
  name: string;

  setName(name: string) {
    this.name = name;
  }
}