handle-done-callback.md

Enforces handling of callbacks for async tests (mocha/handle-done-callback)

💼 This rule is enabled in the ✅ recommended config.

Mocha allows you to write asynchronous tests by adding a done callback to the parameters of your test function. It is easy to forget calling this callback after the asynchronous operation is done.

Example:

it('should work', function (done) {
    fetchData(options, function (error, data) {
        expect(error).not.to.be.ok;
        expect(data).to.deep.equal({ foo: 'bar' });
        // done callback was not called
    });
});

In this example the done callback was never called and test will time out.

Rule Details

This rule checks each FunctionExpression or ArrowFunctionExpression inside of it, it.only, test, test.only, specify, specify.only, before, after, beforeEach and afterEach.

The following patterns are considered warnings:

it('foo', function (done) { });

it('foo', function (done) {
    asyncFunction(function (err, result) {
        expect(err).to.not.exist;
    });
});

before(function (done) {
    asyncInitialization(function () {
        initialized = true;
    });
});

These patterns would not be considered warnings:

it('foo', function (done) { done(); });

it('foo', function (done) {
    asyncFunction(function (err, result) {
        expect(err).to.not.exist;
        done();
    });
});

before(function (done) {
    asyncInitialization(function () {
        initialized = true;
        done();
    });
});

Options

This rule supports the following options:

• ignoreSkipped: When set to true skipped test cases won’t be checked. Defaults to false.

{
    "rules": {
        "mocha/handle-done-callback": ["error", {"ignoreSkipped": true}]
    }
}

When Not To Use It

If you don’t write asynchronous tests you can safely disable this rule.

Further Reading

• Asynchronous test code