Good morning Engine developers, As of this morning, oVirt Engine has migrated to the next generation of Mockito, specifically, the latest available version - 2.6.5 (well, the latest version at the time this email was issued. Their z-stream are as small as a single patch, and thus REALLY fast). First of all - a big shout-out to everyone who took the time to review and comment on this patch series. Why did we do this? 1. The Mockito 1.x generation is no longer supported, and we want to work with a live, maintained, library. 2. Support for Java 8 syntax. 3. Improved generics support, lending to cleaner code. 4. Improved performance. Unfortunately(?), the Mockito 2.x generation isn't 100% backwards compatible. Here are the main changes you need to know about. **"Sneaky" Behavior Changes:** 1. In Mockito 1.x, stubbing a mock and then not using this recorded behavior was not an issue (besides the fact that you're probably writing unused code :-)). In Mokcito 2.x, by default, having unused stubbing will fail your test. Usually, the best course of action is to remove these useless stubbings (as I've done for most of the occurrences in the code). If this isn't easily possible (e.g., these stubbings are inherited from a base class), or if removing them would actually make the test less easy to follow, you can use the org.mockito.junit.MockitoJUnitRunner.Silent runner to revert to Mockito 1.x's behavior. 2. In Mockito 1.x, any(Class) also matches nulls (e.g., any(SomeClass.class) would match any instance of SomeClass or null). In Mockito 2.x, any(Class) *no longer matches nulls*. In order to also match nulls you could use any() or nullable(Class). **Code Changes** 1. Mockito 2.x's ArgumentMatcher no longer extend Hamcrest's Matcher, and was in fact converted to a [functional] interface. Beyond the simple change of using "implements" instead of "extends", this also means you can write much cleaner code and have your matchers as anonymous lambdas. If you still want to use a Hamcrest matcher for your stubbing, you can use org.mockito.hamcrest.MockitoHamcrest#argThat. 2. anyListOf/anySetOf/anyCollectionOf/anyMapOf are now deprecated and should not be used (well, at least mostly - see below). Their counterparts, anyList/anySet/anyCollection/anyMap no longer return raw types, but generalized ones. Utilizing Java 8's type inference, Mockito 2.x allows you to use the simpler versions without getting unchecked assignments warnings. Note that this capability depends on Java's language level, so frontend projects that still use Java 7 will have to use the deprecated versions, unfortunately. I've already applied this change to the entire backend, but you should note it when writing new patches. 3. anyObject() is deprecated - just use any() instead. I've already applied this change to the entire project, but you should note it when writing new patches. 4. org.mockito.runners.MockitoJUnitRunner has been hollowed out and deprecated. Use org.mockito.junit.MockitoJUnitRunner (or org.mockito.junit.MockitoJUnitRunner.Silent, as explained above) instead. I've already applied this change to the entire project, but you should note it when writing new patches. 5. org.mockito.Matchers has been hollowed out and deprecated. Use org.mockito.ArgumentMatchers instead. I've already applied this change to the entire project, but you should note it when writing new patches. Additional information is available on Mockito's website [1], and specifically the "What's new in Mockito 2" page [2]. If you have any other questions, feel free to reply to this thread or contact me directly. Have a great mocking day, Allon [1] http://site.mockito.org/ [2] https://github.com/mockito/mockito/wiki/What%27s-new-in-Mockito-2