No possbile to set "--workers" via NUnit Engine API - nunit

Question

Nunit command line has arg --worker to set LevelOfParallelism
We are running the test programmatically via NUnit Engine (https://docs.nunit.org/articles/nunit-engine/Getting-Started.html)
And I could not find a way to set "worker" in Test Engine or Test Runner
Maybe someone knows how to do this?
I've Google and debugged Test runner - could not find anything
UPDATE:
package = new TestPackage(arguments.Value.testDllPath); package.AddSetting(FrameworkPackageSettings.NumberOfTestWorkers, 8);

Answer 1

Short answer...
Add a setting to the TestPackage you use to get a runner from the engine named "NumberOfTestWorkers" with the value set to the number of workers you want the framework to use.
Details...
This is not actually part of the engine but part of the NUnit framework. The engine is generally framework-agnostic, that is, it doesn't assume you are running tests with the NUnit framework. However, it passes through any settings on the package, which it doesn't understand. It's up to the test framework in use to interpret them.
That's why you can't find the details in the engine documentation, although it could probably be improved by adding a paragraph like the above somewhere. :-)
Bear in mind that writing your own test runner using the engine directly is a somewhat advanced activity. I think the engine docs give you a lot of info about how to get started but you will also need to examine source code of existing open-source runners. For example, looking at the console runner itself, you could have seen this code (reformatted to fit):
if (options.NumberOfTestWorkersSpecified)
package.AddSetting(
FrameworkPackageSettings.NumberOfTestWorkers,
options.NumberOfTestWorkers);
The class FrameworkPackageSettings is part of the runner and includes settings used by the NUnit3 framework and exposed by the runner.
Good luck!