EasyMock calls hashcode when creating constructor and throwing a NullPointerException

Question

I do not understand why EasyMock automatically calls hashcode() before assigning values for properties. When I'm creating the constructor in test class, instead of setting the value for properties, it calls hashcode() that is overridden and throwing an NullPointerException. I used EasyMock combined with PowerMock for Junittest

The code looks like as following:

Class Customer{
/**
* Creating a constructor
*/
 public Customer(String name, String familyName, B b) throws IllegalArgumentException{
         initAttr(name, familyName, b);
 }

 private void initAttr(String name, String familyName, B b) throws IllegalArgumentException{
        if (name == null || familyName == null || b == null)
              throw new  IllegalArgumentException("Invalid input");
         this.name = name;
         this.familyName = familyName;
         this.b = b;


 }

/**
*Test will call this method before setting value for properties
* so now : name and familyName is null-> throw an exception
**/
@Override
  public int hashCode() {
      // Very simple approach:
   // Using Joshua Bloch's recipe:
  int result = 17;
  result = 37 * result + this.name.hashCode();
  result = 37 * result + this.familyName.hashCode();
  return result;
}

}

I implement a test class:

@RunWith(PowerMockRunner.class)
@PrepareForTest({Customer.class, Datutil.class})

class TestCustomer{

        void setUp{

        mockB = createMock(B.class)

       }



        @Test
       public void testConstructor(){

       //do replay()...<br/>

        a = new Customer("name","faname", mockB);//the error happens here

        //do verify()...<br/>

    }

    }

Thanks very much.

Here is the error log:

java.lang.NullPointerException
    at lib.customer.Customer.hashCode(Customer.java:253)
    at java.util.HashMap.hash(Unknown Source)
    at java.util.HashMap.getEntry(Unknown Source)
    at java.util.HashMap.get(Unknown Source)
    at org.powermock.core.MockRepository.getInstanceMethodInvocationControl(MockRepository.java:136)
    at org.powermock.core.MockGateway.doMethodCall(MockGateway.java:57)
    at org.powermock.core.MockGateway.methodCall(MockGateway.java:84)
    at lib.customer.Customer.initAttr(Customer.java)
    at lib.customer.Customer.<init>(Customer.java:96)
    at test.lib.customer.TestCustomer.testConstructor(TestCustomer.java:122)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$2.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:217)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:88)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:96)

I guess A and Customer are in fact the same class? Please show us the full stack trace of the exception. You've not mocked A/Customer, so there's0 reason for Easymock to call `hashCode()`. — JB Nizet, May 05 '13 at 17:57
The error happens in Client.hashCode(). What's this new class? It's impossible to answer the question if the code you're showing doesn't map with what the error messages indicate. CReate an SSCCE reproducing the problem, and show us the real and complete code of the SSCCE — JB Nizet, May 05 '13 at 18:03
sorry @JBNizet for missing, I updated the error log but it did not work properly. Now I did it again. — xuongrong, May 06 '13 at 09:13
1. you still did not provide the code for class B 2. You should make your hashCode method nullsafe or just use apache commons' [HashCodeBuilder](http://www.jarvana.com/jarvana/view/commons-lang/commons-lang/2.4/commons-lang-2.4-sources.jar!/org/apache/commons/lang/builder/HashCodeBuilder.java?format=ok) which does exactly the same as you do — Marco Forberg, May 06 '13 at 11:35
B is class and there is no problem with it. But I did not understand why the test will call hashCode() 1st before assigning the value for properties (name va familyName). If the hashCode is called later, exception will not happen, WHO CAN HEP ME ANSWER WHY? — xuongrong, May 06 '13 at 12:30
Hi admin,Please close this issue. I fixed it. I got troubles because when I call expect(xx,yy), I have to verify EasyMock.expect(). I guess the Junit calls PowerMock.expect. Thanks everyone — xuongrong, May 07 '13 at 09:43

EasyMock calls hashcode when creating constructor and throwing a NullPointerException

0 Answers0