Testing. No 'Access-Control-Allow-Origin' header is present on the requested resource

In back end are apply script security.

1. When I run ng serve project works, I can login and use.
2. When I run ng test project show this error:

context.html:1 Failed to load http://xxxx:8083/Login: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:9800' is therefore not allowed access.

Can you ask me, what is the problem please?

Thank you!