User475983607 posted
This is an ASP.NET support forum not WinForms. So you are in the wrong support forum.
I have a winforms project , and want to create some coded ui tests . Being able to start the winforms exe and populate controls and check the result.
You are describing integration tests not unit tests.
Is Nunit the best software to do this or are there other options ?
Nunit is a unit test framework that has been around a long time and works well. But "Best" depends on what you;re looking for and it seems, at least from the description, you're looking for integration testing.
My best advice is giving Nunit a try and see if you like it.