raise NoSuchElementException for relative failures instead of IndexError (#10078)

symonk · AutomatedTester · web-flow · commit c188fe858a48 · 2021-11-30T11:38:34.000Z
Co-authored-by: David Burns &lt;david.burns@theautomatedtester.co.uk&gt;
diff --git a/py/selenium/webdriver/remote/webdriver.py b/py/selenium/webdriver/remote/webdriver.py
@@ -45,7 +45,8 @@
 from selenium.common.exceptions import (InvalidArgumentException,
                                         JavascriptException,
                                         WebDriverException,
-                                        NoSuchCookieException)
+                                        NoSuchCookieException,
+                                        NoSuchElementException)
 from selenium.webdriver.common.by import By
 from selenium.webdriver.common.options import BaseOptions
 from selenium.webdriver.common.print_page_options import PrintOptions
@@ -1227,7 +1228,10 @@ def find_element(self, by=By.ID, value=None) -> WebElement:
         :rtype: WebElement
         """
         if isinstance(by, RelativeBy):
-            return self.find_elements(by=by, value=value)[0]
+            elements = self.find_elements(by=by, value=value)
+            if not elements:
+                raise NoSuchElementException(f"Cannot locate relative element with: {by.root}")
+            return elements[0]
 
         if by == By.ID:
             by = By.CSS_SELECTOR
diff --git a/py/test/selenium/webdriver/support/relative_by_tests.py b/py/test/selenium/webdriver/support/relative_by_tests.py
@@ -14,9 +14,10 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-
+from selenium.common.exceptions import NoSuchElementException
 from selenium.webdriver.common.by import By
 from selenium.webdriver.support.relative_locator import with_tag_name, locate_with
+import pytest
 
 
 def test_should_be_able_to_find_first_one(driver, pages):
@@ -67,3 +68,11 @@ def test_should_be_able_to_use_xpath(driver, pages):
 
     ids = [el.get_attribute('id') for el in elements]
     assert "fourth" in ids
+
+
+def test_no_such_element_is_raised_rather_than_index_error(driver, pages):
+    pages.load("relative_locators.html")
+    with pytest.raises(NoSuchElementException) as exc:
+        anchor = driver.find_element(By.ID, "second")
+        driver.find_element(locate_with(By.ID, "nonexistentid").above(anchor))
+    assert exc.value.msg == "Cannot locate relative element with: {'id': 'nonexistentid'}"
