[js] until.alertIsPresent(): Workaround for GeckoDriver conversion error (#2137)

* [js] until.alertIsPresent(): Workaround for GeckoDriver conversion error

* Narrow down check on WebDriverError

* Add tests

* Updated CHANGES.md

Author: JohanLorenzo

javascript/node/selenium-webdriver/CHANGES.md

@@ -4,6 +4,7 @@
    `builder.Builder#usingHttpAgent()`
 * Added new wait conditions: `until.urlIs()`, `until.urlContains()`,
    `until.urlMatches()`
+* Added work around for [GeckoDriver bug](https://bugzilla.mozilla.org/show_bug.cgi?id=1274924) raising a type conversion error
 
 ## v2.53.2
 

javascript/node/selenium-webdriver/lib/until.js

@@ -115,7 +115,13 @@ exports.ableToSwitchToFrame = function ableToSwitchToFrame(frame) {
 exports.alertIsPresent = function alertIsPresent() {
   return new Condition('for alert to be present', function(driver) {
     return driver.switchTo().alert().catch(function(e) {
-      if (!(e instanceof error.NoSuchAlertError)) {
+      if (!(e instanceof error.NoSuchAlertError
+        // XXX: Workaround for GeckoDriver error `TypeError: can't convert null
+        // to object`. For more details, see
+        // https://github.com/SeleniumHQ/selenium/pull/2137
+        || (e instanceof error.WebDriverError
+          && e.message === `can't convert null to object`)
+        )) {
         throw e;
       }
     });

javascript/node/selenium-webdriver/test/lib/until_test.js

@@ -145,6 +145,40 @@ describe('until', function() {
         return alert.dismiss();
       });
     });
+
+    // TODO: Remove once GeckoDriver doesn't throw this unwanted error.
+    // See https://github.com/SeleniumHQ/selenium/pull/2137
+    describe('workaround for GeckoDriver', function() {
+      it('doesNotFailWhenCannotConvertNullToObject', function() {
+        var count = 0;
+        executor.on(CommandName.GET_ALERT_TEXT, function() {
+          if (count++ < 3) {
+            throw new error.WebDriverError(`can't convert null to object`);
+          } else {
+            return true;
+          }
+        }).on(CommandName.DISMISS_ALERT, () => true);
+
+        return driver.wait(until.alertIsPresent(), 1000).then(function(alert) {
+          assert.equal(count, 4);
+          return alert.dismiss();
+        });
+      });
+
+      it('keepsRaisingRegularWebdriverError', function() {
+        var webDriverError = new error.WebDriverError;
+
+        executor.on(CommandName.GET_ALERT_TEXT, function() {
+          throw webDriverError;
+        });
+
+        return driver.wait(until.alertIsPresent(), 1000).then(function() {
+          throw new Error('driver did not fail against WebDriverError');
+        }, function(error) {
+          assert.equal(error, webDriverError);
+        });
+      })
+    });
   });
 
   it('testUntilTitleIs', function() {