recursive datastructures where recursive field is ignored

[chisui]

What steps will reproduce the problem?

The EqualsVerifier expects prefab values for recursive datastructures even when the recursive fields are ignored.

What is the code that triggers this problem?

class A {
    A a;
    String b;

    @Override public boolean equals(Object obj) { ... }
    @Override public int hashCode() { ... }
}

EqualsVerifier.forClass(A.class)
        .withIgnoredFields("a")
        .verify();

The actual implementations of equals(Object) and hashCode() are irrelevant.

What error message or stack trace does EqualsVerifier give?

java.lang.AssertionError: Recursive datastructure.
Add prefab values for one of the following types: A.
For more information, go to: http://www.jqno.nl/equalsverifier/errormessages
  at nl.jqno.equalsverifier.EqualsVerifier.handleError(EqualsVerifier.java:381)
  at nl.jqno.equalsverifier.EqualsVerifier.verify(EqualsVerifier.java:367)

What did you expect?

The EqualsVerifier should not require prefab values for A.

Which version of EqualsVerifier are you using?

2.1.5

Please provide any additional information below.

This also happens if the recursive field is a Collection.

[jqno]

Hi,

Unfortunately, it's still necessary to add prefab values for ignored fields if they're recursive. EqualsVerifier will ignore them for checking the equals contract, but it can't know if the fields aren't called in equals or hashCode anyway. For example, you class could theoretically contain a cache that is not part of the contract, but that's consulted in the equals method anyway.

I realize that it's not very intuitive, so I've added a short explanation to the website: http://jqno.nl/equalsverifier/errormessages/recursive-datastructure/