To write browser tests in C#, use NUnit to discover and run test cases and report assertions, and Selenium WebDriver to control a real browser. Start with the NUnit project template, add Selenium’s .NET package, create and quit a browser driver for each test, then run the suite with dotnet test.
What NUnit and Selenium each do
Your test code calls Selenium’s .NET binding. WebDriver sends browser commands through a browser-specific driver, which controls the browser. NUnit supplies test discovery, lifecycle hooks such as setup and teardown, assertions, and test results. Selenium’s documentation makes the distinction explicit: “WebDriver does not know a thing about testing: it does not know how to compare things, assert pass or fail, and it certainly does not know a thing about reporting or Given/When/Then grammar.”
This separation is useful when diagnosing failures: an assertion failure is a test result from NUnit, while navigation and element interactions are handled by Selenium and the browser driver. The browser and driver do not have to run on the same system as the test code.
Create a C# NUnit project and install Selenium
Install the .NET SDK and create a project from the NUnit starter template. Selenium’s .NET setup documentation uses SDK 8.0 or later for its example test suite; that is the stated prerequisite for that example, not a universal minimum for every project. The Selenium install guide’s package examples showed version 4.49.0 when checked on October 3, 2026; the Selenium project lists that version as released September 9, 2026. Package releases and compatibility can change, so use mutually compatible current stable versions for a new project.
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Create a directory for the test project, open a terminal there, and run
dotnet new NUnit. -
Add the Selenium .NET binding from NuGet with
dotnet add package Selenium.WebDriver. If you use another browser than Chrome, install that browser and use its corresponding Selenium driver class. -
Restore dependencies with
dotnet restore. -
Add a test class containing a test method and run it with
dotnet test.
The NUnit starter template supplies the test-runner dependencies and an initial test project. Keep the Selenium browser-control dependency distinct from the packages that make the project discoverable and runnable as an NUnit suite.
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Write a browser test with per-test setup and cleanup
This example opens a public test page, enters a query, submits it, waits for a visible result, and asserts the result text. It creates a fresh Chrome session for each test and quits it in teardown, including when an assertion fails.
using NUnit.Framework;
using OpenQA.Selenium;
using OpenQA.Selenium.Chrome;
using OpenQA.Selenium.Support.UI;
[TestFixture]
public class SearchTests
{
private IWebDriver? _driver;
[SetUp]
public void SetUp()
{
_driver = new ChromeDriver();
}
[TearDown]
public void TearDown()
{
_driver?.Quit();
_driver?.Dispose();
}
[Test]
public void SearchShowsTheSubmittedTerm()
{
var driver = _driver!;
driver.Navigate().GoToUrl("https://www.selenium.dev/selenium/web/web-form.html");
driver.FindElement(By.Name("my-text")).SendKeys("NUnit Selenium");
driver.FindElement(By.CssSelector("button")).Click();
var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(10));
var result = wait.Until(d => d.FindElement(By.Id("message")));
Assert.That(result.Text, Is.EqualTo("Received!"));
}
}For this example, include using System; if your project’s implicit usings are disabled, and add the Selenium support package if your project does not already resolve WebDriverWait. The page and its form are a demonstration target; for a long-lived suite, prefer a test page you control and selectors that are stable parts of its test contract. This code is illustrative and is not presented as an independently executed test.
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Why this lifecycle is a sound default
-
[SetUp]runs before each test case, and[TearDown]runs after each test case. A new session per test reduces state leakage between tests. -
Quit()closes the browser session; disposing the driver releases its client-side resources. Keep cleanup in teardown rather than after the assertion, so an assertion exception does not skip cleanup.Crashes, No Sound, or Screen Glitches?
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[OneTimeSetUp]and[OneTimeTearDown]run once for the fixture scope. They can be appropriate for genuinely shared fixture resources, but sharing a browser session can make browser state bleed between tests. -
Avoid multiple setup methods on one class when their order matters: NUnit does not define their relative order.
Run all tests or select one test
From the project directory, run:
dotnet restore
dotnet testTo run a single fully qualified test method, use the filter format shown in Selenium’s .NET documentation, replacing the example namespace, class, and method with yours:
dotnet test --filter "FullyQualifiedName=Namespace.ClassName.MethodName"The test runner reports discovered tests and their pass or fail results. If no tests are discovered, confirm that the project uses NUnit test-runner dependencies from the template and that the method is marked with [Test].
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How Selenium starts the browser driver
With current Selenium releases, a beginner generally does not need to download a matching driver executable manually. Selenium Manager has been bundled with Selenium starting with Selenium 4.6. When the binding has not been given a driver, Selenium Manager can discover browser and driver versions, download a needed driver, and cache it for later use.
Manual driver provisioning remains useful in controlled CI environments, restricted networks, or other setups where the executable and browser versions are managed explicitly. If you provide a driver yourself, ensure it is compatible with the installed browser and that the test process can access it. Selenium’s driver-management behavior and browser packaging can change across environments; consult the current setup documentation if automatic resolution fails.
Wait for conditions instead of sleeping
Pages that load data asynchronously may not be ready at the moment a click or navigation command returns. Use an explicit wait for the condition the next step needs, as the example does for the result element, rather than adding a fixed sleep. A fixed delay is either wasteful when the page is fast or unreliable when it takes longer than the chosen interval.
-
Wait for a specific element to exist or become visible before reading or interacting with it.
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Wait for a known state change after a click, such as a confirmation message or a changed URL.
-
Keep the timeout bounded and make the assertion describe the outcome the user cares about.
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Common failures and practical fixes
Driver or browser startup fails
-
Likely cause: The browser is missing, the environment cannot download a driver, or an explicitly supplied driver is incompatible.
-
Fix: Confirm the browser is installed and available to the test process. If relying on Selenium Manager, check network and cache permissions; if provisioning manually, align the driver with the browser and make its location available to Selenium.
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An element lookup fails immediately after navigation
-
Likely cause: The page has not reached the required state yet, or the locator no longer matches the page.
-
Fix: Inspect the page and locator, then wait explicitly for the element or state required by the test. Avoid treating a longer arbitrary sleep as the general solution.
Tests pass alone but fail in a suite
-
Likely cause: Tests share browser state or another fixture resource, or cleanup was skipped after a failure.
-
Fix: Use a per-test driver by default and close it in teardown. If a shared resource is intentional, make its lifecycle and test ordering requirements explicit rather than relying on incidental execution order.
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dotnet test reports no tests
-
Likely cause: The test method or test-runner dependencies are missing or the wrong project directory is being tested.
-
Fix: Run the command from the project directory, verify the project was created from the NUnit template, and check that the method has the NUnit
[Test]attribute.
When to move from local browsers to Grid
Local WebDriver is the simplest place to develop and debug a first browser test. Selenium Grid and RemoteWebDriver move browser sessions to remote infrastructure, which can run separately from the test process and distribute execution across machines.
| Choice | Where the session runs | Browser and operating-system coverage | Scale and operational trade-off |
|---|---|---|---|
| Local WebDriver | On the developer or CI machine running the test. | Limited to browsers and operating systems available on that machine. | Simple to start and debug; capacity depends on the local machine and its browser setup. |
| RemoteWebDriver / Selenium Grid | On a remote Grid node or other remote browser infrastructure. | Can use browsers and operating systems provided by the remote infrastructure. | Can distribute browser work across machines; requires operating or arranging the remote infrastructure. Provider pricing and availability depend on the offering and are not established here. |
Grid is a next step when browser sessions need to run away from the developer machine or execution needs to scale across machines. First get the local test stable; then move session creation to a remote endpoint and manage the Grid’s browser and node configuration separately.
Or skip the browser setup
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Frequently Asked Questions
Can I use NUnit and Selenium with browsers other than Chrome?
Yes. Selenium supports browser-specific drivers; use the driver class and installed browser appropriate to your target browser.
Does Selenium include NUnit assertions?
No. Selenium controls the browser, while NUnit supplies assertions and test discovery and reporting.
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