Symmetry: ConcreteSubclass does not equal superclass instance AbstractSuperclass

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What steps will reproduce the problem?

1. Create abstract superclass AbstractSuperclass that does neither declare 
equals() nor hashCode()
2. Create concrete subclass ConcreteSubclass that implements both equals() and 
hashCode()
3. Run EqualsVerifier.forClass(ConcreteSubclass.class).verify()

What error message does EqualsVerifier give?

java.lang.AssertionError: Symmetry:
  ConcreteSubclass [intValue=1, super=AbstractSuperclass [stringValue=one]]
does not equal superclass instance
  AbstractSuperclass [stringValue=one]

What stacktrace does EqualsVerifier print, when called with the debug()
method?

java.lang.AssertionError: Symmetry:
  ConcreteSubclass [intValue=1, super=AbstractSuperclass [stringValue=one]]
does not equal superclass instance
  AbstractSuperclass [stringValue=one]
    at nl.jqno.equalsverifier.util.Assert.assertTrue(Assert.java:85)
    at nl.jqno.equalsverifier.HierarchyChecker.checkSuperclass(HierarchyChecker.java:92)
    at nl.jqno.equalsverifier.HierarchyChecker.check(HierarchyChecker.java:61)
    at nl.jqno.equalsverifier.EqualsVerifier.verifyWithExamples(EqualsVerifier.java:396)
    at nl.jqno.equalsverifier.EqualsVerifier.performVerification(EqualsVerifier.java:366)
    at nl.jqno.equalsverifier.EqualsVerifier.verify(EqualsVerifier.java:333)
    at equalsverifier.ContractTest.equalsContract(ContractTest.java:11)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

What did you expect?

Test should pass.

What version of EqualsVerifier are you using?

1.1.3

Please provide any additional information below.

Equalsverifier complains that concrete subclass does not equal *abstract* 
superclass instance. However, an abstract class is not intended to be 
instantiated.

As workaround, one can define both equals() and hashCode() as abstract in 
AbstractSuperclass:

    @Override
    public abstract boolean equals(Object obj);

    @Override
    public abstract int hashCode();

Then, the tests will pass as in line 78 of class HierarchyChecker there is a 
check whether hashCode() is abstract in superclass.

Original issue reported on code.google.com by mburger313@gmail.com on 8 May 2012 at 1:03

Attachments:

• AbstractSuperclass.java
• ConcreteSubclass.java
• ContractTest.java