Structure for unit tests?

Question

Unit testing

How to structure a project with tests correctly?
Is it acceptable to place class tests in the same structure as in the main project?
Well, i.e.

MainProject/Program.cs
and the test for this class would be
MainProject.Tests/ProgramTest.cs

MainProject/Shared/Helper.cs
and the test for this class would be
MainProject.Tests/SharedTests/HelperTest.cs

for clarity, I'll attach a screenshot

And how to separate unit tests from integration tests? Move it to a separate project?
For example:
1) MainProject
2) MainProject.UnitTests
3) MainProject.IntegrationTests

Answer 1

I would choose the first option, and I would solve the issue with integration tests by dividing them into suites (you can put them in different folders.
That is, it will be like this:
and tests for this class will be

MainProject.Tests/Unit/ProgramTest.cs
MainProject.Tests/Integration/ProgramTest.robot