gulp + mocha + typescript unit test - node.js

Question

I have an error when I create new instance on test file.
This is my test:
/// <reference path="../typings/globals/mocha/index.d.ts" />
import Person from '../src/person/person';
describe('Person', () => {
let person: Person;
beforeEach(() => {
person = new Person();
});
describe('getName', () => {
it('return name', () => {
});
});
});
And my gulp task:
var gulp = require("gulp");
var ts = require("gulp-typescript");
var mocha = require("gulp-mocha");
var tsProject = ts.createProject("./tsconfig.json");
gulp.task('watch', function () {
gulp.watch('./src/**/**/*.ts', ['ts']);
});
gulp.task('ts', function () {
return tsProject.src()
.pipe(tsProject())
.js.pipe(gulp.dest("dist"));
});
gulp.task('test', function () {
return gulp.src('./tests/*.spec.ts',
{
base: '.'
})
/*transpile*/
.pipe(tsProject())
/*flush to disk*/
.pipe(gulp.dest('.'))
/*execute tests*/
.pipe(mocha())
.on("error", function(err) {
console.log(err)
});
});
gulp.task("default", ['watch', 'ts']);
So, when I launch the test an error occured, but if I comment person = new Person() then everything works.
Somebody knows what I am doing wrong?
EDIT:
Sorry, this is the error:
module.js:472
throw err;
^
Error: Cannot find module '../src/person/person'
at Function.Module._resolveFilename (module.js:470:15)
at Function.Module._load (module.js:418:25)
at Module.require (module.js:498:17)
at require (internal/module.js:20:19)
at Object.<anonymous> (/Users/emesislol/projects/persons/tests/person.test.js:4:21)
at Module._compile (module.js:571:32)
at Object.Module._extensions..js (module.js:580:10)
at Module.load (module.js:488:32)
at tryModuleLoad (module.js:447:12)
at Function.Module._load (module.js:439:3)
at Module.require (module.js:498:17)
at require (internal/module.js:20:19)
at /Users/emesislol/projects/persons/node_modules/mocha/lib/mocha.js:222:27
at Array.forEach (native)
at Mocha.loadFiles (/Users/emesislol/projects/persons/node_modules/mocha/lib/mocha.js:219:14)
at Mocha.run (/Users/emesislol/projects/persons/node_modules/mocha/lib/mocha.js:487:10)
at Object.<anonymous> (/Users/emesislol/projects/persons/node_modules/mocha/bin/_mocha:459:18)
at Module._compile (module.js:571:32)
at Object.Module._extensions..js (module.js:580:10)
at Module.load (module.js:488:32)
at tryModuleLoad (module.js:447:12)
at Function.Module._load (module.js:439:3)
at Module.runMain (module.js:605:10)
at run (bootstrap_node.js:420:7)
at startup (bootstrap_node.js:139:9)
at bootstrap_node.js:535:3