fix unhandled rejections in handlers (#798)

resolves #792

Author: yaronassa

features/hooks.feature

@@ -253,6 +253,53 @@ Feature: Environment Hooks
       ]
       """
 
+  Scenario: Failing the BeforeFeatures hook exists immediately with code = 1
+    Given a file named "features/a.feature" with:
+      """
+      Feature: some feature
+
+      Scenario: I've declared one step and it is passing
+          Given This step is passing
+      """
+    And a file named "features/step_definitions/cucumber_steps.js" with:
+      """
+      var cucumberSteps = function() {
+        this.Given(/^This step is passing$/, function(callback) { console.log('is passing'); callback(); });
+      };
+      module.exports = cucumberSteps;
+      """
+    And a file named "features/support/hooks.js" with:
+      """
+      var hooks = function () {
+        this.registerHandler('BeforeFeatures', function(){
+          return {
+            then: function(resolve, reject){
+              setTimeout(function(){
+                reject(new Error('Something bad'))
+              });
+            }
+          };
+        });
+      };
+
+      module.exports = hooks;
+      """
+    When I run cucumber.js with `-f json`
+    Then the exit status should be non-zero
+    And the error output contains the text: 
+      """
+      features/support/hooks.js:2 Something bad
+      """
+    And the output does not contain the text:
+      """
+      is passing
+      """
+    And the error output does not contain the text:
+      """
+      is passing
+      """
+    
+
   Scenario: Hooks still execute after a failure
     Given a file named "features/a.feature" with:
       """

features/step_definitions/cli_steps.js

@@ -63,16 +63,21 @@ var cliSteps = function cliSteps() {
                       getAdditionalErrorText(this.lastRun));
   });
 
-  this.Then(/^the (error )?output contains the text:$/, function(error, expectedOutput) {
+  this.Then(/^the (error )?output (does not)? ?contains? the text:$/, function(error, shouldFind, expectedOutput) {
+    var expectedToFind = !(shouldFind);
     var actualOutput = error ? this.lastRun.stderr : this.lastRun.stdout;
 
     actualOutput = normalizeText(actualOutput);
     expectedOutput = normalizeText(expectedOutput);
 
-    if (actualOutput.indexOf(expectedOutput) === -1)
-      throw new Error('Expected output to contain the following:\n' + expectedOutput + '\n' +
-                      'Got:\n' + actualOutput + '\n' +
-                      getAdditionalErrorText(this.lastRun));
+      if ((actualOutput.indexOf(expectedOutput) !== -1) !== expectedToFind) {
+          var errorPhrase = (expectedToFind) ? 'Expected output to contain the following:' : 'Expected output not to contain the following:';
+
+          throw new Error(errorPhrase + '\n' + expectedOutput + '\n' +
+              'Got:\n' + actualOutput + '\n' +
+              getAdditionalErrorText(this.lastRun));
+      }
+
   });
 
   this.Then(/^I see the version of Cucumber$/, function() {

lib/cucumber/runtime/event_broadcaster.js

@@ -27,7 +27,7 @@ function EventBroadcaster(listeners, listenerDefaultTimeout) {
       Cucumber.Util.asyncForEach(listeners, function (listener, callback) {
         listener.hear(event, listenerDefaultTimeout, function(error) {
           if (error) {
-            throw error;
+            process.nextTick(function(){ throw error; }); // prevent swallow by unhandled rejection
           }
           callback();
         });