spring boot - Failing while testing autowired field using Junit -

am new junit, solution below issue welcomed. have main class like,

@service public class mainclass extends abstractclass {  @autowired classa a;  @autowired objectmapper mapper;  public void methoda(){ .... anotherclass obj= (anotherclass)mapper.readerfor(anotherclass.class).readvalue(some_code); ....... } 

test class is,

@runwith(powermockrunner.class) @preparefortest({mainclass.class}) public class mainclasstest {  @mock classa a;  @mock objectmapper mapper;  @injectmocks mainclass process = new mainclass();  //i have somthing autowired mapper class of main in test class  @test public void testprocessrequest() throws exception{     process.methoda() } 

am getting null mapper object in main class while testing, yes aware haven't dne kind of initialization. there better way writing junit mapper. note : tried @mock objectmapper throws exception @ "readerfor". in advance.

you not have use mockito/powermock. use spring boot test. this:

import org.junit.test; import org.junit.runner.runwith; import org.springframework.beans.factory.annotation.autowired; import org.springframework.boot.test.context.springboottest; import org.springframework.test.context.junit4.springrunner;  import com.fasterxml.jackson.databind.objectmapper;  @runwith(springrunner.class) @springboottest public class someservicetest {      @autowired     private someservice service;      @autowired     private objectmapper om;      @test     public void  try_me(){         system.out.println(om);     } } 

adding info more question. if want use mockito objectmapper should prepare mock. if not when calling readerfor(...) mock returns null default , later, in readvalue method, getting nullpointer.

a basic preparation mock might be:

objectreader or = mockito.mock(objectreader.class); mockito.when(or.readvalue(mockito.anystring())).thenreturn(new instance of object); mockito.when(mapper.readerfor(user.class)).thenreturn(or);