junit - Mockito: Getting ClassCastException from a constructor call with a mock as argument -

i want unit test method signature as

public oracle.sql.array  methoda(java.sql.connection connection) 

the connection object mocked using

mockito.mock(connection.class) 

and passed methoda while testing it.

oracle.sql.array has constructor

new array(oracle.sql.arraydescriptor, connection, object) 

the methoda has logic obtaining arraydescriptor. has logic providing third argument constructor provides array of objects

i mocking these 2 set of logics , passing mocked arraydescriptor object , mocked object array. these mocking work correctly.

so constructor invocation like

new array(arraydescriptormock, connectionmock, objectmock) 

this constructor call throws exception when executed part of test

java.lang.classcastexception:$java.sql.connection$$enhancerbymockitowithcglib$$2427854e cannot cast oracle.jdbc.oracleconnection

i have made many attempts mock constructor call avoiding error. however, each proved futile. documenting mocking code constructor

attempt1

 powermockito.whennew(array.class).withparametertypes(arraydescriptor.class, connection.class, object.class)             .witharguments(any(arraydescriptor.class), any(connection.class), any(object[].class))             .thenreturn(expectedarray); 

attempt2

  powermockito.whennew(array.class).witharguments(arraydescriptormock,connectionmock,objectarraymock).thenreturn(expectedarray); 

legend: arraydescriptormock: mock of arraydescriptor

connectionmock: mock of connection

objectarraymock: mock of object array mocking code as

  object[] structarraymock = new object[2];        struct obj1 = mock(struct.class);        struct obj2 = mock(struct.class);        structarraymock[0] = obj1;        structarraymock[1] = obj2; 

notes: method under test has following code did not mock

 object[] objarray = new object[2]; 

i using powermockito, mockito , testng. however, believe issue has nothing testng, therefore junit tag should fine.

kindly advise why classcastexception coming , how avoid it?

edit believe mockito suppose intercept constructor call. meaning should not allow execution of real constructor. suppose return mock object of array class. why not happen? why attempting casting ?

the beginning of answer in straightforward message of exception.

... cannot cast oracle.jdbc.oracleconnection 

the code shows oracle.sql.array object oracle driver don't accept object (and mocks) implementing jdbc interface such java.sql.connection. somehow expected connector architecture, jdbc included follows jca principles.

why expected because objects jca implementation need know / interact own objects internally. java.sql.connection interface minimal usable contract must exists clients spi (jdbc there).

so given fact , oracle.sql.array oracle driver type, expected object needs internal oracle.sql.connection behave normally. mocking oracle.jdbc.oracleconnection won't array using coupled type in more ways expected, , lead hellish fixture.

ussually we, mockists, : "don't mock types don't own. that's not mocking oracle.sql.connection. in test don't see why test code written else , jdbc driver if 1 driver developer.

if need test daos or repositories uses array, writing integration tests (with real oracle) better fit.

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to answer intention, go it. here's why :

actually tested code involves proprietary types @ point. , these types come driver must connect real database provide connection work with. don't see easy way unit test,

• maybe there's hidden types in oracle driver can help, that's maybe , introduce fragility , difficulty refactor if later team decides change database.
• or can use mock of array, break purpose specific test

and must add first reason reason why write integration tests when system needs connect another. cover application boundaries, including persistence. call business api of repositories (which daos business oriented api) , job whatever datastore behind. oracle or others change implementation of driver, remove types, etc. , don't have rewrite tests, actual implementation.