Framework Drivers

Framework Drivers are extensions that know how to create a driver for a particular framework. The NUnit engine provides drivers for both the NUnit 3.x and NUnit 2.x frameworks. Third parties may provide drivers for other frameworks by creating extensions.

The ExtensionPoint for framework drivers uses the Path "NUnit.Engine.DriverService" and accepts an extension of Type NUnit.Engine.Extensibility.IDriverFactory. The definition of a driver factory might look like this:

[Extension]
public class MyOwnFrameworkDriverFactory : IDriverFactory
{
    ...
}

The `IDriverFactory` interface is defined as follows:

```C#
public interface IDriverFactory
{
    // Gets a flag indicating whether the provided assembly name and version
    // represent a test framework supported by this factory
    bool IsSupportedTestFramework(string assemblyName, Version version);

    // Gets a driver for use with the specified framework assembly name and version
    IFrameworkDriver GetDriver(AppDomain domain, string assemblyName, Version version);
}

The IFrameworkDriver interface is defined as follows:

public interface IFrameworkDriver
{
    // Gets and sets the unique identfier for this driver
    string ID { get; set; }

    // Loads the tests in an assembly
    string Load(string testAssemblyPath, IDictionary<string, object> settings);

    // Counts the test cases that would be executed
    int CountTestCases(string filter);

    // Executes the tests in an assembly
    string Run(ITestEventListener listener, string filter);

    // Returns information about the tests in an assembly
    string Explore(string filter);

    // Cancels an ongoing test run.
    void StopRun(bool force);

The strings returned by Run and Explore are XML representations and the filter is also in XML format. See the source code for NUnit3FrameworkDriver and NUnit2FrameworkDriver for details.