Requires .Net 5.

All tests are unit tests. You can run the tests with your preferred test runner, or using the standard command line:

dotnet test

Regarding the test "WeekdaysAndBusinessDayTests.GivenHolidayList_BusinessDayCalculation_ShouldNotIncludeHolidays()". InlineData was preferred over MemberData here as the dates and holiday list are more readable.