fix(protractor): allow exceptions from actions to be catchable

See #959

Author: hankduan

Diff for: lib/protractor.js

@@ -110,12 +110,14 @@ var buildElementHelper = function(ptor) {
         return parentWebElement.findElements(this.locator_);
       }
     } else {
-      ptor.waitForAngular();
-      if (this.locator_.findElementsOverride) {
-        return this.locator_.findElementsOverride(ptor.driver);
-      } else {
-        return ptor.driver.findElements(this.locator_);
-      }
+      var self = this; 
+      return ptor.waitForAngular().then(function() {
+        if (self.locator_.findElementsOverride) {
+          return self.locator_.findElementsOverride(ptor.driver);
+        } else {
+          return ptor.driver.findElements(self.locator_);
+        }
+      });
     }
   };
 
@@ -470,8 +472,13 @@ var buildElementHelper = function(ptor) {
     WEB_ELEMENT_FUNCTIONS.forEach(function(fnName) {
       if(!self[fnName]) {
         self[fnName] = function() {
-          var webElem = self.getWebElement(); 
-          var actionResult = webElem[fnName].apply(webElem, arguments);
+          var args = arguments;
+          var webElem = self.getWebElement();
+          var actionResult = webElem.then(
+              function(webElem_) {
+                return webElem_[fnName].apply(webElem_, args);
+              });
+
           return new ElementFinder(
               locator, opt_parentElementFinder, 
               actionResult, opt_index);
@@ -722,11 +729,9 @@ var buildElementHelper = function(ptor) {
    * @return {webdriver.promise.Promise} Promise which contains the results of 
    *     evaluating fn.
    */
-  ElementFinder.prototype.then = function(fn) {
+  ElementFinder.prototype.then = function(fn, errorFn) {
     if (this.opt_actionResult_) {
-      return this.opt_actionResult_.then(function() {
-        return fn.apply(null, arguments);
-      });
+      return this.opt_actionResult_.then(fn, errorFn);
     } else {
       return fn(this);
     }

Diff for: spec/basic/elements_spec.js

@@ -292,6 +292,19 @@ describe('ElementFinder', function() {
     expect(element(byCss).locator()).toEqual(byCss);
     expect(element(byBinding).locator()).toEqual(byBinding);
   });
+
+  it('should propagate exceptions', function() {
+    browser.get('index.html#/form');
+    var successful = protractor.promise.defer();
+
+    var invalidElement = element(by.binding('INVALID'));
+    invalidElement.getText().then(function(value) {
+      successful.fulfill(true);
+    }, function(err) {
+      successful.fulfill(false);
+    });
+    expect(successful).toEqual(false);
+  });
 });
 
 describe('evaluating statements', function() {