Runtime Selection

By default, NUnit runs tests under the runtime version for which the test assembly was built, provided it is available on the test machine. If it is not available, NUnit runs the assembly under the best available runtime that will allow it to run. If no suitable runtime can be found, an error is reported.

Overriding the Defaults

The default runtime framework may be overridden using command line options. In all cases, NUnit will attempt to honor the options given, issuing an error message if the assembly cannot be loaded. See Console Command Line for more information.

• The /framework option of console runner allows you to specify the framework type and version to be used for a test run. When this option is used, NUnit will attempt to run the tests under the framework specified even if the assembly targets a different runtime.
• The /process:Single command-line option indicates that tests should be run in the NUnit process itself. This forces usage of the runtime under which NUnit is already running.
• The process:Separate causes a single separate process to be used for all assemblies. In this case, NUnit will use the highest level runtime targeted by any of the assemblies, if it is available.