Is it possible to Reset an object in a test

Question

Adam Kirk · Answer

Have a look at <http mockk io|mockk io>

ghedeon · Answer

You won t believe me but it s called `reset ` in Mockito slightly smiling face It s also a sign of a poor test

LeoColman · Answer

I meant resetting a kotlin object declaration

LeoColman · Answer

I m not sure if it s a sign of a poor test My object keeps a map that should be a single instance during the whole JVM

LeoColman · Answer

But one test will dirty another test due to this map as I m not able to reset the JVM in execution

LeoColman · Answer

So I wanted to reinitialize this singleton only for tests but in a real environment this will never happen

gildor · Answer

gt My object keeps a map that should be a single instance during the whole JVM I agree with < ghedeon> it looks as some bad design and hack for test

Jonathan Mew · Answer

< LeoColman> I would recommend using a DI framework to own this map The map instance could be created as part of creating some overall application object The framework can then inject the shared instance into the constructors of any objects that require access to it Then for tests that require a fully wired up application you can create a brand new application instance and for unit tests you can provide a map instance for the object you are testing Plenty of benefits in moving towards that kind of model Statically accessible mutable state is a common pain point and worth avoiding where you can

Jonathan Mew · Answer

It s totally possible to do something like ``` BeforeEach fun beforeEach myStaticMap clear ``` but it s pretty hacky and I think it ll burn you sooner or later

Mike · Answer

< ghedeon> agree that using reset on Mockito mockk is often a smell but if you re using junit5 and life cycle of instance it now becomes mandatory A blog post about doing that to improve performance of you re tests As it s faster to reset a mock than to create a new one Pros and cons to this approach like all decisions we make

LeoColman · Answer

I m creating a library and basically the whole point of it is to have this static map

LeoColman · Answer

It s a very small library which only point is to hold onto key value and act upon these

LeoColman · Answer

It has 2 classes Wiring up a DI framework factory out the class creation and such seems a bit overkill for this very simple thing

LeoColman · Answer

I thought that maybe I could delete the instance via reflection or something just for the test that uses the class that keeps the map

Mike · Answer

I think your best route may be a `internal fun clear ` defined in your structure that clears it out Won t be visible outside the module but will be available to tests I don t think there s a way to clear memory structure from code otherwise

Jonathan Mew · Answer

For consumers of your library will their tests then hit the same problem though

LeoColman · Answer

That s right < Jonathan Mew> I didn t think of that possibility