Injecting Clock in Java

A lightning presentation on using injected Clock instances from JSR-310 (Java 8's java.time.*).

1. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock
2. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock is about
3. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock is about
4. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock is about
5. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock is about
6. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Injecting Clock is about
7. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. Why do we care? •  You can write tests that do not depend on when they are run – Ward against Daylight Savings transition •  You can write tests for specific timing conditions – Test these “after NN hours” rules •  Offers another way of controlling timezone to be used by some code – More selective than default time zone
8. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. How does it work?
9. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. How does it work?
10. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. How does it work?
11. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. How does it work?
12. © 2014 RichRelevance, Inc. All Rights Reserved. Confidential. How do I test? •  Inject a clock explicitly – Mocked – From a Clock factory