Concurrent Test Running with Specflow and NUnit 3

A little while back I wrote a post on achieving concurrent or parallel test running with Selenium, Specflow and NUnit2, but what about NUnit3? Let’s have a look at that, thankfully it is a bit simpler than running an external build script as done previously.

First up, according to the Specflow docs – open up your AssemblyInfo.cs file in your project and add the following line:

[assembly: Parallelizable(ParallelScope.Fixtures)]

Next we need to setup/ teardown our browser and config from the Scenario Hook level, doing it in a Test Run Hook will be problematic as it is static. Your Hooks might look similar to this:

public class ScenarioHooks
private readonly IObjectContainer objectContainer;
private IWebDriver Driver;

public ScenarioHooks(IObjectContainer objectContainer)
this.objectContainer = objectContainer;

public void BeforeScenario()
var customCapabilitiesIE = new DesiredCapabilities();
customCapabilitiesIE.SetCapability(CapabilityType.BrowserName, "internet explorer");
customCapabilitiesIE.SetCapability(CapabilityType.Platform, new Platform(PlatformType.Windows));
customCapabilitiesIE.SetCapability("", @"C:\tmp\webdriver\iedriver\iedriver_3.0.0_Win32bit.exe");

Driver = new RemoteWebDriver(new Uri(XXX.XXX.XXX.XXX), customCapabilitiesIE);

public void AfterScenario()

You can see from the browser instantiation we are sending the tests to a Selenium Grid Hub, so as a precursor to running the tests you will need suitable infrastructure to run a grid, or you could configure it to go off to SauceLabs or BrowserStack.

Assuming the hub and nodes are configured correctly, when your build process runs the tests then the hub will farm them out by feature file (for other options see the parallel scope in AssemblyInfo.cs) to achieve concurrent test running, and that’s it! Much nicer.

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