Fix: runner listening to 'start' and 'end' events (#3660)

Author: juergba

lib/runner.js

@@ -939,7 +939,9 @@ Runner.prototype.run = function(fn) {
     this.emit(constants.EVENT_DELAY_BEGIN, rootSuite);
     rootSuite.once(EVENT_ROOT_SUITE_RUN, start);
   } else {
-    start();
+    Runner.immediately(function() {
+      start();
+    });
   }
 
   return this;

test/unit/mocha.spec.js

@@ -487,6 +487,16 @@ describe('Mocha', function() {
       }, 'not to throw');
     });
 
+    it('should catch the `start` event if no tests are provided', function(done) {
+      var mocha = new Mocha(opts);
+      mocha.run().on('start', done);
+    });
+
+    it('should catch the `end` event if no tests are provided', function(done) {
+      var mocha = new Mocha(opts);
+      mocha.run().on('end', done);
+    });
+
     describe('#reporter("xunit")#run(fn)', function() {
       // :TBD: Why does specifying reporter differentiate this test from preceding one
       it('should not raise errors if callback was not provided', function() {