**Describe the bug**
Unit test case failed :
  1) supports http with nodejs
       should pass errors for a failed stream:
     Error: Timeout of 30000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (***************...

**To Reproduce**
Use VS Code internal terminal to excute the unit test .

**Expected behavior**
UT should be excuted correctly.

**Environment:**
 - Axios Version: latest master
 - OS Version: Window 10

**Additional context/Screenshots**
![Capture](https://user-images.githubusercontent.com/46782518/70436361-136c5380-1ac4-11ea-87b5-203b2e46ebbf.PNG)

test/unit/adapters/http.js
});
  it('should support basic auth', function (done) {
    server = http.createServer(function (req, res) {
      res.end(req.headers.authorization);
    }).listen(4444, function () {
      var user = 'foo';
      var headers = { Authorization: 'Bearer 1234' };
      axios.get('http://' + user + '@localhost:4444/', { headers: headers }).then(function (res) {
        var base64 = Buffer.from(user + ':', 'utf8').toString('base64');
        assert.equal(res.data, 'Basic ' + base64);
        done();
      });
    });
  });
  it('should support basic auth with a header', function (done) {
    server = http.createServer(function (req, res) {
      res.end(req.headers.authorization);
    }).listen(4444, function () {
      var auth = { username: 'foo', password: 'bar' };
      var headers = { Authorization: 'Bearer 1234' };
      axios.get('http://localhost:4444/', { auth: auth, headers: headers }).then(function (res) {
        var base64 = Buffer.from('foo:bar', 'utf8').toString('base64');
        assert.equal(res.data, 'Basic ' + base64);
        done();
      });
    });
  });
  it('should support max content length', function (done) {
    var str = Array(100000).join('ж');
    server = http.createServer(function (req, res) {