Tests cannot be run in parallel

[gregorycfrank]

Description

I have a setup very similar to the example in the documentation for TestClock, where I sleep for a second and increment an integer variable in an object on every wake. This incremented value changes state of the containing object based on the value of the variable. I have several tests to check the boundary conditions. When run individually they all pass. When run as part of the suite, they fail. Adding .serialized to the suite lets them all pass again.

This leads me to believe that there is something global happening that causes the tests to step on each other.

Checklist

• If possible, I've reproduced the issue using the main branch of this package.
• This issue hasn't been addressed in an existing GitHub issue or discussion.

Expected behavior

Tests run in parallel have no effect on each other.

Actual behavior

Running tests in parallel cause tests to fail.

Steps to reproduce

If you contact me directly, I can give you read access to my private repo in Bitbucket.

swift-clocks version information

1.0.6

Destination operating system

iOS 26

Xcode version information

Version 26.5 (17F42)

Swift Compiler version information

swift-driver version: 1.148.6 Apple Swift version 6.3.2 (swiftlang-6.3.2.1.108 clang-2100.1.1.101)
Target: arm64-apple-macosx26.0