Injecting Clock in Java

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock is about

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock is about

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock is about

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock is about

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

Injecting Clock is about

© 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

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

How does it work?

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

How does it work?

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

How does it work?

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

How does it work?

© 2014 RichRelevance, Inc. All Rights Reserved. Confidential.

How do I test? •  Inject a clock explicitly

– Mocked – From a Clock factory