Javascript – Mocha + TypeScript: Cannot use import statement outside a module

ecmascript-6javascriptmocha.jsnode.jstypescript

I was watching this video in order to learn how to add some simple tests to my Express routes but I am getting all kind of errors while executing a test. The error is:

import * as chai from 'chai';

^^^^^^

SyntaxError: Cannot use import statement outside a module

I have read some similar Stack Overflow questions and GitHub issues but I didn't find a solution for my own application. Finally I found Mocha documentation on GitHub regarding ES modules but it didn't work:

I created the app using TypeScript and CommonJS module to transpile, so I added "test": "env TS_NODE_COMPILER_OPTIONS='{\"module\": \"commonjs\" }' mocha src/test/*.ts" to the package.json scripts but I am getting the same error every time. I am using ts-node as a server.

Anyway, this is my tsconfig.json file:

{
    "compilerOptions": {
        "sourceMap": true,
        "target": "es6",
        "module": "commonjs",
        "outDir": "./dist",
        "rootDir": "./src"
    },
    "exclude": [
        "node_modules"
    ]
}

And this is the src/test/mi-route.ts file:

import * as chai from 'chai';
import * as chaiHttp from 'chai-http';
import server from '../app';

// Assertions
chai.should();

chai.use(chaiHttp);

describe('API Users', () => {
    // Test Route GET
    describe('GET /api/admin/users', () => {
        it('Should return all the users', done => {
            chai.request(server)
                .get('/api/admin/users')
                .end((err, response) => {
                    response.should.have.status(200);
                    response.body.should.be.a('object');
                    done();
                });
        });
    });
});

An this is my package.json scripts:

"scripts": {
    "dev": "ts-node-dev src/app.ts",
    "start": "node dist/app.js",
    "test": "env TS_NODE_COMPILER_OPTIONS='{\"module\": \"commonjs\" }' mocha src/test/*.ts",
    "build": "tsc -p"
  },

So… any suggestions? Should I change Common JS Module? Thanks in advance

Best Answer

Had the same issue and almost gave up using Mocha with TypeScript (in our case Angular 9).

This is what helped me:

In tsconfig.json:

Replaced this:

"module": "esnext",

with this:

"module": "commonjs",

Also here I found a working example of Mocha with TypeScript and used the tsconfig file from there to compare with mine: https://medium.com/@RupaniChirag/writing-unit-tests-in-typescript-d4719b8a0a40

Related Topic