title: Test if an object conforms to an interface in TypeScript
body: <p>If I have a plain-old JavaScript object and a TypeScript interface, how can I write a test that asserts object conforming to my interface?</p>
  
  <pre><code>interface Person {
    name: string
    age?: number
  }
  
  describe('Person interface check', () =&gt; {
    it ('should conform to "Person" interface', () =&gt; {
       let obj1 = {name: "Mohsen"};
       let obj2 = {name: "Hommer", age: 40};
  
       expect(obj1) // ????
    });
  });
  </code></pre>
  
  <p><strong>EDIT</strong>: I don't want to do deep assertion, eg <code>expect(obj1.name).to.be.a.string</code></p>