Plugins for the ReSharper Platform are just .net assemblies. In order to create a plugin project, you need to:
Create .net class libraries for the plugin, and optionally (but recommended) for tests.
Add NuGet references to the
JetBrains.ReSharper.SDK.Testspackages as appropriate.
Install the project locally in order to manually test and debug.
Modify the project to automatically update the installed plugin on each build.
Once the project has been built and installed locally, it can be manually run for testing or debugging.