junit - J-Unit Test: Make static void method in final class throw exception -

i writing j-unit tests project , problem occured:

i testing servlet uses utility class (class final, methods static). used method returns void , can throw an

ioexception (httpresponse.getwriter).

now have force exception...

i have tried , searched lot, solutions found did not worked, because there no combination of final, static, void, throw.

has did before?

edit: here code snippet

servlet:

protected void dopost(httpservletrequest request, httpservletresponse response) throws ioexception { try {     string action = request.getparameter("action");     if (action.equals("saverule")) {         // code         string resp = "blablabla";         tomamappingutils.evaluatetexttorespond(response, resp);     } } catch (ioexception e) {     tomamappingutils.requesterrorhandling(response, "ioexception", e); } 

}

utils class:

public final class tomamappingutils { private static final logger logger = logger.getlogger(tomamappingutils.class.getname()); private static final gson gson = new gson();  public static void evaluatetexttorespond(httpservletresponse response, string message) throws ioexception {     // code     response.getwriter().write(new gson().tojson(message));  } 

}

test method:

@test public void dopostioexception () {     // set request parameters     when(getmockhttpservletrequest().getparameter("action")).thenreturn("saverule");     // more code     // make tomamappingutils.evaluatetexttorespond throw ioexpection jump in catch block line coverage     when(tomamappingutils.evaluatetexttorespond(getmockhttpservletresponse(), anystring())).thenthrow(new ioexception()); // behaviour want } 

so can see, want force utils method throw ioexception, in catch block better line coverage.

to mock final class, first add in preparefortest.

@preparefortest({ tomamappingutils.class }) 

then mock static class

powermockito.mockstatic(tomamappingutils.class); 

then set expectation below.

powermockito.dothrow(new ioexception())     .when(tomamappingutils.class,             membermatcher.method(tomamappingutils.class,                     "evaluatetexttorespond",httpservletresponse.class, string.class ))     .witharguments(matchers.anyobject(), matchers.anystring()); 

another way:

powermockito     .dothrow(new ioexception())     .when(myhelper.class, "evaluatetexttorespond",               matchers.any(httpservletresponse.class), matchers.anystring());