Install Selenium and nose2 in the same Python environment, write browser checks as discoverable Python tests, and run nose2 from your project directory. Selenium drives the browser; nose2 finds and runs the tests. The guide below shows a minimal setup, reliable waits, discovery options, and common fixes.
What Selenium and nose2 each do
Selenium’s WebDriver is a language-neutral interface and protocol for controlling a browser. The Selenium Python bindings let Python code open pages, locate elements, and interact with them. nose2 is a test runner based on Python’s unittest; it discovers tests, runs them, and reports results. Selenium documentation · nose2 documentation
In practice, Selenium performs browser actions and exposes browser state, while nose2 decides which tests to run. nose2 is not a Selenium plugin that drives the browser, and Selenium does not discover your test files.
Install the packages in a project environment
A virtual environment keeps test dependencies separate from other Python projects. From the project directory, create and activate one using the command for your operating system and shell, then install both packages:
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python -m venv .venv
# Activate .venv using the command for your OS and shell.
python -m pip install -U selenium nose2The nose2 getting-started guide documents pip install nose2; Selenium’s Python API documentation documents pip install -U selenium and recommends considering a virtual environment. Check your project’s Python, browser, and package compatibility before pinning versions. The nose2 documentation index lists version 0.16.0, released 2026-03-01; Selenium’s Python API documentation identified 4.49.0 as its latest release when checked on 2026-10-03. Those release identifiers can change.
Write a test nose2 will discover
By default, nose2 looks for Python modules whose filenames begin with test, then loads recognized test functions and unittest.TestCase test methods whose names begin with test. A file named test_example.py follows the default filename pattern; example_test.py does not.
Save this as test_example.py in your project’s test directory:
import unittest
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.support.ui import WebDriverWait
class TestExamplePage(unittest.TestCase):
def setUp(self):
self.driver = webdriver.Chrome()
def tearDown(self):
if hasattr(self, "driver"):
self.driver.quit()
def test_page_has_heading(self):
self.driver.get("https://example.com")
heading = WebDriverWait(self.driver, 10).until(
EC.presence_of_element_located((By.TAG_NAME, "h1"))
)
self.assertTrue(heading.text)
This is an illustrative pattern, not a claim about a live page’s contents. setUp starts a browser for each test, and tearDown closes it so a passing or failing test does not leave the session running. For a larger suite, consider sharing setup only when doing so does not make tests depend on one another.
Run the suite and control discovery
Run default discovery
From the project directory, run:
nose2If the command is not on your shell’s PATH, run the module through the active Python environment:
python -m nose2Keep the environment activated so nose2 and Selenium are imported from the same place where they were installed.
Set the test directory or import root
If the default search does not match your repository structure, supply a start directory and, when needed, the top-level import directory:
nose2 -s tests -t .-s (or --start-dir) tells nose2 where discovery begins. -t (or --top-level-directory) sets the importable project root. Adjust these paths to your layout; for example, if tests live under src/project/tests, use that as the start directory and choose the directory that makes your project imports resolve as the top level.
Run one test by dotted name
nose2 also accepts dotted names to select a test module, class, or individual test. For example, with test_example.py in the importable test directory, run:
nose2 test_example.TestExamplePage.test_page_has_headingThe exact dotted name depends on the module’s import path from the configured top-level directory.
Configure discovery in a file
nose2 can read configuration from files such as unittest.cfg or nose2.cfg. The configuration can set discovery-related values such as the start directory, code directories, file patterns, and plugins. Use command-line options for a quick one-off run and a configuration file when the same layout applies consistently across local and automated runs. nose2’s discovery and loading are plugin-based; using --no-plugins disables the normal discovery and loading behavior, so it is not a general fix for tests that are not being found.
Wait for browser state, not an arbitrary delay
A successful navigation call does not mean JavaScript-driven content is ready for the next action. An explicit wait polls for a named condition at the point the test needs it. The example waits up to ten seconds for an h1 element to be present; the wait can return sooner when the condition becomes true, or raise a timeout if it does not.
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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsImplicit waits instead affect element lookups by polling for elements that are not immediately available. Mixing implicit and explicit waits can make timing harder to reason about. A fixed time.sleep always delays for its full duration and can still be too short when a page is slow. Prefer a condition that represents the state under test, such as presence, visibility, or clickability. Selenium’s waits guide describes these patterns; because that Python guide is older, check its exact imports and behavior against the Selenium version installed in your project. Selenium waits documentation
Choose local execution or Selenium Grid
A local WebDriver session is the simplest place to develop a test: it controls a browser available in the same environment. Selenium Grid is the project’s documented route for scaling execution across remote browser environments. Grid can expand where and in which browser configuration tests run, but it adds setup and operational requirements. Start locally while debugging test logic; consider Grid when the suite needs remote or broader browser execution. Selenium’s documentation identifies Grid as the scaling path but does not establish a particular hosted provider or price. Selenium documentation
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Do you still need to install a browser driver manually?
For modern Selenium versions, Selenium Manager generally handles driver setup for supported browsers and platforms, so manual driver downloads and PATH configuration are not usually needed. This depends on the browser and platform being supported and correctly installed. If startup fails, check the browser installation, Selenium version, and the specific error before following older tutorials that prescribe manual driver downloads. Selenium Manager documentation
Troubleshoot common failures
- nose2 reports no tests found: Check that the file begins with
test, the test method or function begins withtest, and you ran nose2 from the intended project directory. Trynose2 -s tests -t .with paths matching your layout. - Import errors for Selenium or nose2: Activate the project environment and install both packages with that environment’s Python using
python -m pip install -U selenium nose2. Confirm thatpythonandnose2resolve to the environment you expect. - Browser session fails to start: Verify the browser is installed and supported by your Selenium version and platform. Modern Selenium generally uses Selenium Manager; manual driver setup may still be needed in unsupported or constrained environments, but first inspect the actual startup error rather than assuming a missing PATH entry.
- Element lookup raises a no-such-element error: The locator may not match, or the element may not exist yet. Verify the selector in the current page state and wait for the relevant condition before interacting.
- An explicit wait times out: The condition did not become true before its maximum wait. Check whether navigation reached the expected page, the locator is correct, or the element is inside a frame or otherwise unavailable in the current context.
- Tests leave browsers open: Ensure cleanup runs after failures. Keep browser shutdown in
tearDownor use a cleanup strategy that is guaranteed to execute when test assertions fail. - Tests pass individually but fail in a suite: Look for shared browser state, cookies, data, or order-dependent assumptions. Isolate test setup and cleanup so each test starts from a known state.
Or skip the browser setup
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Frequently Asked Questions
Does nose2 replace unittest?
No. nose2 is based on unittest and adds discovery, running, and plugin support; unittest provides the test case structure used in the example.
Can nose2 run Selenium tests without opening a browser?
A normal Selenium WebDriver test controls a browser session. A screenshot API can capture a page without a test-controlled browser, but it does not perform the interactions or assertions of a Selenium test.
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