How to capture a list of specific type with mockito

Question

Is there a way to capture a list of specific type using mockitos ArgumentCaptore  This doesn t work   ArgumentCaptor lt ArrayList lt SomeType gt  gt  argument   ArgumentCaptor forClass ArrayList class

User · Answer

For an earlier version of junit  you can do  Class lt Map lt String  String gt  gt  mapClass    Class  Map class  ArgumentCaptor lt Map lt String  String gt  gt  mapCaptor   ArgumentCaptor forClass mapClass

User · Answer

Yeah  this is a general generics problem  not mockito-specific   There is no class object for ArrayList lt SomeType gt   and thus you can t type-safely pass such an object to a method requiring a Class lt ArrayList lt SomeType gt  gt    You can cast the object to the right type   Class lt ArrayList lt SomeType gt  gt  listClass                  Class lt ArrayList lt SomeType gt  gt   Class ArrayList class  ArgumentCaptor lt ArrayList lt SomeType gt  gt  argument   ArgumentCaptor forClass listClass     This will give some warnings about unsafe casts  and of course your ArgumentCaptor can t really differentiate between ArrayList lt SomeType gt  and ArrayList lt AnotherType gt  without maybe inspecting the elements    As mentioned in the other answer  while this is a general generics problem  there is a Mockito-specific solution for the type-safety problem with the  Captor annotation  It still can t distinguish between an ArrayList lt SomeType gt  and an ArrayList lt OtherType gt     Edit   Take also a look at tenshis comment  You can change the original code from Paulo Ebermann to this  much simpler   final ArgumentCaptor lt List lt SomeType gt  gt  listCaptor           ArgumentCaptor forClass  Class  List class

User · Answer

List lt String gt  mockedList   mock List class    List lt String gt  l   new ArrayList    l add  someElement     mockedList addAll l    ArgumentCaptor lt List gt  argumentCaptor   ArgumentCaptor forClass List class    verify mockedList  addAll argumentCaptor capture      List lt String gt  capturedArgument   argumentCaptor  lt List lt String gt  gt getValue     assertThat capturedArgument  hasItem  someElement

User · Answer

The nested generics-problem can be avoided with the  Captor annotation   public class Test        Mock     private Service service        Captor     private ArgumentCaptor lt ArrayList lt SomeType gt  gt  captor        Before     public void init            MockitoAnnotations initMocks this               Test      public void shouldDoStuffWithListValues                           verify service  doStuff captor capture

User · Answer

I had the same issue with testing activity in my Android app  I used ActivityInstrumentationTestCase2 and MockitoAnnotations initMocks this   didn t work  I solved this issue with another class with respectively field  For example   class CaptorHolder             Captor         ArgumentCaptor lt Callback lt AuthResponse gt  gt  captor           public CaptorHolder                 MockitoAnnotations initMocks this                     Then  in activity test method   HubstaffService hubstaffService   mock HubstaffService class   fragment setHubstaffService hubstaffService    CaptorHolder captorHolder   new CaptorHolder    ArgumentCaptor lt Callback lt AuthResponse gt  gt  captor   captorHolder captor   onView withId R id signInBtn            perform click      verify hubstaffService  authorize anyString    anyString    captor capture     Callback lt AuthResponse gt  callback   captor getValue

User · Answer

If you re not afraid of old java-style  non type safe generic  semantics  this also works and is simple ish  ArgumentCaptor lt List gt  argument   ArgumentCaptor forClass List class   verify subject method argument capture        run your code List lt SomeType gt  list   argument getValue       first captured List  etc

User · Answer

There is an open issue in Mockito s GitHub about this exact problem   I have found a simple workaround that does not force you to use annotations in your tests   import org mockito ArgumentCaptor  import org mockito Captor  import org mockito MockitoAnnotations   public final class MockitoCaptorExtensions        public static  lt T gt  ArgumentCaptor lt T gt  captorFor final CaptorTypeReference lt T gt  argumentTypeReference            return new CaptorContainer lt T gt    captor             public static  lt T gt  ArgumentCaptor lt T gt  captorFor final Class lt T gt  argumentClass            return ArgumentCaptor forClass argumentClass              public interface CaptorTypeReference lt T gt             static  lt T gt  CaptorTypeReference lt T gt  genericType                 return new CaptorTypeReference lt T gt                                        default T nullOfGenericType                 return null                        private static final class CaptorContainer lt T gt              Captor         private ArgumentCaptor lt T gt  captor           private CaptorContainer                 MockitoAnnotations initMocks this                         What happens here is that we create a new class with the  Captor annotation and inject the captor into it  Then we just extract the captor and return it from our static method   In your test you can use it like so   ArgumentCaptor lt Supplier lt Set lt List lt Object gt  gt  gt  gt  fancyCaptor   captorFor genericType       Or with syntax that resembles Jackson s TypeReference   ArgumentCaptor lt Supplier lt Set lt List lt Object gt  gt  gt  gt  fancyCaptor   captorFor      new CaptorTypeReference lt Supplier lt Set lt List lt Object gt  gt  gt  gt                 It works  because Mockito doesn t actually need any type information  unlike serializers  for example

User · Answer

Based on  tenshi s and  pkalinow s comments  also kudos to  rogerdpack   the following is a simple solution for creating a list argument captor that also disables the  uses unchecked or unsafe operations  warning    SuppressWarnings  unchecked   final ArgumentCaptor lt List lt SomeType gt  gt  someTypeListArgumentCaptor       ArgumentCaptor forClass List class     Full example here and corresponding passing CI build and test run here   Our team has been using this for some time in our unit tests and this looks like the most straightforward solution for us

[java] How to capture a list of specific type with mockito

Examples related to java

Examples related to unit-testing

Examples related to junit

Examples related to mockito