Handle server not-running & superagent system errors (#348)

* Handle server not-running & network errors

Handles server not-running (ECONNREFUSED) and other system errors from
superagent

* Test errors corrected

.gitignore

@@ -1 +1,3 @@
 node_modules
+.idea
+*.log

lib/test.js

@@ -148,6 +148,24 @@ Test.prototype.assert = function(resError, res, fn) {
   var error;
   var i;
 
+  // check for unexpected network errors or server not running/reachable errors
+  // when there is no response and superagent sends back a System Error
+  // do not check further for other asserts, if any, in such case
+  // https://nodejs.org/api/errors.html#errors_common_system_errors
+  var sysErrors = {
+    ECONNREFUSED: 'Connection refused',
+    ECONNRESET: 'Connection reset by peer',
+    EPIPE: 'Broken pipe',
+    ETIMEDOUT: 'Operation timed out'
+  };
+
+  if (!res && resError && (resError instanceof Error) && (resError.syscall === 'connect')
+      && (Object.getOwnPropertyNames(sysErrors).indexOf(resError.code) >= 0)) {
+    error = new Error(resError.code + ': ' + sysErrors[resError.code]);
+    fn.call(this, error, null);
+    return;
+  }
+
   // asserts
   for (i = 0; i < this._asserts.length && !error; ++i) {
     error = this._assertFunction(this._asserts[i], res);

test/supertest.js

@@ -360,6 +360,20 @@ describe('request(app)', function() {
     });
   });
 
+  describe('.expect(status)', function () {
+    it('should handle connection error', function (done) {
+      var req = request.agent('http://localhost:1234');
+
+      req
+          .get('/')
+          .expect(200)
+          .end(function (err, res) {
+            err.message.should.equal('ECONNREFUSED: Connection refused');
+            done();
+          });
+    });
+  });
+
   describe('.expect(status)', function () {
     it('should assert only status', function (done) {
       var app = express();