Clock in Spring Integration Tests

Today, we had a team debate about our Integration Tests (spring application) - during which - two different Clock approaches emerged.

1) We Should always use fixed Clock implementation during our unit/integration tests

• It drives your code to always include Clock in constructor (DI), so to be testable
• It makes easy to control time flow (in tests that need it)
• Makes tests more "descriptive" because, you literally show class relation to time flow

2) Use fixed Clock implementation ONLY when your TestClass explicitly needs it to control time flow.

• Integration tests should use closest to production implementation possible

So #1 approach buffs test classes, but #2 seems to be "more true" in some situations.

And the question: How do you handle Clock/Time in your Projects? Please share your experience and arguments!