diff --git a/test/supertest.js b/test/supertest.js
index 7561d1f..d108b63 100644
--- a/test/supertest.js
+++ b/test/supertest.js
@@ -1269,7 +1269,7 @@ describe('request.get(url).query(vals) works as expected', function () {
       });
   });
 
-  it('handles unknown errors', function (done) {
+  it('handles unknown errors (err without res)', function (done) {
     const app = express();
 
     nock.disableNetConnect();
@@ -1285,6 +1285,8 @@ describe('request.get(url).query(vals) works as expected', function () {
       // https://github.com/visionmedia/supertest/issues/352
       .expect(200)
       .end(function (err, res) {
+        should.exist(err);
+        should.not.exist(res);
         err.should.be.an.instanceof(Error);
         err.message.should.match(/Nock: Disallowed net connect/);
         shouldIncludeStackWithThisFile(err);
@@ -1294,6 +1296,35 @@ describe('request.get(url).query(vals) works as expected', function () {
     nock.restore();
   });
 
+  // this scenario should never happen
+  // there shouldn't be any res if there is an err
+  // meant for test coverage for lib/test.js#169
+  // https://github.com/visionmedia/supertest/blob/5543d674cf9aa4547927ba6010d31d9474950dec/lib/test.js#L169
+  it('handles unknown errors (err with res)', function (done) {
+    const app = express();
+
+    app.get('/', function (req, res) {
+      res.status(200).send('OK');
+    });
+
+    const resError = new Error();
+    resError.status = 400;
+
+    const serverRes = { status: 200 };
+
+    request(app)
+      .get('/')
+      // private api
+      .assert(resError, serverRes, function (err, res) {
+        should.exist(err);
+        should.exist(res);
+        err.should.equal(resError);
+        res.should.equal(serverRes);
+        // close the server explicitly (as we are not using expect/end/then)
+        this.end(done);
+      });
+  });
+
   it('should assert using promises', function (done) {
     const app = express();