Spring Polish some test classes by using predefined constants

By changing the magic number to a constant, it has been improved to safer test code.

Comment From: sbrannen

Please execute ./gradlew check, fix the build errors (due to changed import order), and push the changes to the PR.

Thanks

Comment From: hyeonisism

@sbrannen I fixed it. Thanks

Comment From: sbrannen

This has been merged into master.

Thanks