setup in xunit

https://xunit.github.io/docs/shared-context

Shared Context between Tests

It is common for unit test classes to share setup and cleanup code (often called "test context"). xUnit.net offers several methods for sharing this setup and cleanup code, depending on the scope of things to be shared, as well as the expense associated with the setup and cleanup code.

• Constructor and Dispose (shared setup/cleanup code without sharing object instances)
• Class Fixtures (shared object instance across tests in a single class)
• Collection Fixtures (shared object instances across multiple test classes)