From d113e69a87f2ecaa3a4c48492197f7d76b6d7fa0 Mon Sep 17 00:00:00 2001
From: Jonathan Davies <jpds@protonmail.com>
Date: Thu, 5 Mar 2026 11:14:46 +0000
Subject: [PATCH] nixos/prometheus: tests: ui: fix race conditions in Selenium
 assertions

Use explicit WebDriverWait conditions instead of immediate assertions
for elements whose content is populated asynchronously by JavaScript.
URL redirects, query results, health status, and version info may not
be ready immediately, causing flaky failures. Also replace locate_with
relative locator with a direct XPath selector for the version check.
---
 nixos/tests/prometheus/ui.nix | 44 +++++++++++++++--------------------
 1 file changed, 19 insertions(+), 25 deletions(-)

diff --git a/nixos/tests/prometheus/ui.nix b/nixos/tests/prometheus/ui.nix
index 3ef784f3ad8b..b46766ffd253 100644
--- a/nixos/tests/prometheus/ui.nix
+++ b/nixos/tests/prometheus/ui.nix
@@ -20,7 +20,7 @@
                   from selenium import webdriver
                   from selenium.webdriver.common.by import By
                   from selenium.webdriver.firefox.options import Options
-                  from selenium.webdriver.support.relative_locator import locate_with
+                  from selenium.webdriver.support import expected_conditions as EC
                   from selenium.webdriver.support.ui import WebDriverWait
 
                   options = Options()
@@ -35,13 +35,12 @@
                   wait = WebDriverWait(driver, 60)
 
                   # There should have been a redirect
-                  url = driver.current_url
-                  assert url == "http://prometheus:9090/query"
+                  wait.until(EC.url_to_be("http://prometheus:9090/query"))
 
-                  assert len(driver.find_elements(
-                    By.CLASS_NAME, "mantine-AppShell-header")) > 0
-                  assert len(driver.find_elements(
-                    By.CLASS_NAME, "mantine-AppShell-main")) > 0
+                  wait.until(EC.presence_of_element_located(
+                    (By.CLASS_NAME, "mantine-AppShell-header")))
+                  wait.until(EC.presence_of_element_located(
+                    (By.CLASS_NAME, "mantine-AppShell-main")))
 
                   # Do a Prometheus query
                   query_box = driver.find_element(
@@ -53,10 +52,9 @@
                   driver.find_element(
                     By.XPATH, "//span[contains(text(),'Execute')]").click()
 
-                  # Find query result table
-                  table_tr_elements = driver.find_elements(
-                    By.CLASS_NAME, "mantine-Table-tr")
-                  assert len(table_tr_elements) == 1
+                  # Wait for query result table
+                  wait.until(EC.presence_of_element_located(
+                    (By.CLASS_NAME, "mantine-Table-tr")))
 
                   # Navigate to target health page
                   driver.find_element(
@@ -65,16 +63,14 @@
                   driver.find_element(
                     By.LINK_TEXT, "Target health").click()
 
-                  url = driver.current_url
-                  assert url == "http://prometheus:9090/targets"
+                  wait.until(EC.url_to_be("http://prometheus:9090/targets"))
 
                   # Click on the prometheus job dropdown button
-                  prometheus_job_dropdown = driver.find_element(
+                  driver.find_element(
                     By.CLASS_NAME, "mantine-Accordion-chevron").click()
 
-                  targets_healthy = len(driver.find_elements(
-                    By.CSS_SELECTOR, "div[class^='_healthOk']"))
-                  assert targets_healthy == 1
+                  wait.until(EC.presence_of_element_located(
+                    (By.CSS_SELECTOR, "div[class^='_healthOk']")))
 
                   targets_errored = len(driver.find_elements(
                     By.CSS_SELECTOR, "div[class^='_healthErr']"))
@@ -92,15 +88,13 @@
                   driver.find_element(
                     By.LINK_TEXT, "Runtime & build information").click()
 
-                  url = driver.current_url
-                  assert url == "http://prometheus:9090/status"
+                  wait.until(EC.url_to_be("http://prometheus:9090/status"))
 
-                  # Find table
-                  version_th_element = driver.find_element(
-                    By.XPATH, "//th[text()='version']")
-                  version_td_element = driver.find_element(
-                    locate_with(By.TAG_NAME, "td").near(version_th_element))
-                  assert version_td_element.text == "${pkgs.prometheus.version}"
+                  # Find table and verify version
+                  wait.until(EC.text_to_be_present_in_element(
+                    (By.XPATH,
+                     "//tr[th[text()='version']]/td"),
+                    "${pkgs.prometheus.version}"))
 
                   driver.close()
                 '';