Temporal table syntax in a view
Use a table valued function (TVF).
CREATE FUNCTION dbo.TVF_func (@_timestamp DATETIME2)
RETURNS TABLE AS
RETURN
SELECT T.*
  FROM [tests]
  FOR SYSTEM_TIME AS OF @_timestamp T;

The TVF can then be used anywhere a view can be used.
SELECT * 
  FROM dbo.TVF_func('2020-10-31') T 
  JOIN [etc...]

For views with complex logic where you typically select a subset of the output based on a date variable, you can get a massive speed boost from rewriting the view as a TVF instead of SELECT * FROM view V WHERE V.date = @date.