UnexpectedAlertPresentException should contain the alert text in python too.

Fixes Issue #7745

Author: lukeis

py/selenium/common/exceptions.py

@@ -124,7 +124,12 @@ class UnexpectedAlertPresentException(WebDriverException):
     Usually raised when when an expected modal is blocking webdriver form executing any 
     more commands.
     """
-    pass
+    def __init__(self, msg=None, screen=None, stacktrace=None, alert_text=None):
+        super(WebDriverException, self).__init__(msg, screen, stacktrace)
+        self.alert_text = alert_text
+
+    def __str__(self):
+        return "Alert Text: %s\n%s" % (self.alert_text, str(super(WebDriverException, self)))
 
 class NoAlertPresentException(WebDriverException):
     """

py/selenium/webdriver/remote/errorhandler.py

@@ -161,6 +161,8 @@ def check_response(self, response):
                 pass
         if exception_class == ErrorInResponseException:
             raise exception_class(response, message)
+        elif exception_class == UnexpectedAlertPresentException and 'alert' in value:
+            raise exception_class(message, screen, stacktrace, value['alert'].get('text'))
         raise exception_class(message, screen, stacktrace)
 
     def _value_or_default(self, obj, key, default):

py/test/selenium/webdriver/common/alerts_tests.py

@@ -20,6 +20,7 @@
 from selenium.common.exceptions import ElementNotVisibleException
 from selenium.common.exceptions import InvalidElementStateException
 from selenium.common.exceptions import NoAlertPresentException
+from selenium.common.exceptions import UnexpectedAlertPresentException
 
 import unittest
 
@@ -214,6 +215,18 @@ def testShouldAllowTheUserToGetTheTextOfAnAlert(self):
         alert.accept()
         self.assertEqual("cheese", value)
 
+    def testUnexpectedAlertPresentExceptionContainsAlertText(self):
+        self._loadPage("alerts")
+        self.driver.find_element(by=By.ID, value="alert").click()
+        alert = self._waitForAlert()
+        value = alert.text
+        try:
+            self._loadPage("simpleTest")
+            raise Exception("UnexpectedAlertPresentException should have been thrown")
+        except UnexpectedAlertPresentException as uape:
+            self.assertEquals(value, uape.alert_text)
+            self.assertTrue(str(uape).startswith("Alert Text: %s" % value))
+
     def _waitForAlert(self):
         return WebDriverWait(self.driver, 3).until(EC.alert_is_present())