Not catching exceptions?

Unit Test:

describe('check unhandled exceptions', () => {
     it ('should log error and exit if unhandled exception is caught', ()=> {
        let options = {
            log: console.log,
            err: console.error  };
        let errSpy = sinon.spy(options, 'err');
        let expOut = "Server has crashed with Error: We Crashed!";
        app.crash();
        expect( errSpy.calledWith(expOut) ).to.be.true;
     })
});


Output:
 1 failing
 
 1) check unhandled exceptions should log error and exit if unhandled exception is caught:
    Error: We Crashed!
     at APP.crash (lib\src\app.ts:48:15)
     at Context.it (lib\specs\app.spec.ts:87:9)
     
     
     
 Code:
 
 export class APP {

   constructor() {
      process.on('uncaughtException', err => {
        console.error("Server has crashed with ", err);
        process.exit(1);
      });
   }
    crash(){
       throw new Error("We Crashed!");
    }