Equalsverifier fails when run with quarkus:dev

Question

When running equalsverfier in quarkus dev mode, equalsverfier tests fail.

I tried to test a class with equalsverifier. This works in my IDE. I tried to use it in quarkus dev mode (by running./mvnw quarkus:dev), but then it fails with the following exception:

ERROR [io.qua.test] (Test runner thread) Test DingetjeTest#implementsEquals() failed 
: java.lang.AssertionError: EqualsVerifier found a problem in class a.Dingetje.
-> Can not set final java.lang.String field a.Dingetje.text to a.Dingetje

For more information, go to: http://www.jqno.nl/equalsverifier/errormessages
        at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verify(SingleTypeEqualsVerifierApi.java:308)
        at a.DingetjeTest.implementsEquals(DingetjeTest.java:11)
Caused by: java.lang.IllegalArgumentException: Can not set final java.lang.String field a.Dingetje.text to a.Dingetje
        at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
        at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
        at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
        at java.base/jdk.internal.reflect.UnsafeQualifiedObjectFieldAccessorImpl.get(UnsafeQualifiedObjectFieldAccessorImpl.java:38)
        at java.base/java.lang.reflect.Field.get(Field.java:418)
        at nl.jqno.equalsverifier.internal.reflection.FieldModifier.lambda$copyTo$1(FieldModifier.java:79)
        at nl.jqno.equalsverifier.internal.reflection.FieldModifier.lambda$change$3(FieldModifier.java:113)
        at nl.jqno.equalsverifier.internal.util.Rethrow.lambda$rethrow$0(Rethrow.java:47)
        at nl.jqno.equalsverifier.internal.util.Rethrow.rethrow(Rethrow.java:30)
        at nl.jqno.equalsverifier.internal.util.Rethrow.rethrow(Rethrow.java:45)
        at nl.jqno.equalsverifier.internal.util.Rethrow.rethrow(Rethrow.java:55)
        at nl.jqno.equalsverifier.internal.reflection.FieldModifier.change(FieldModifier.java:113)
        at nl.jqno.equalsverifier.internal.reflection.FieldModifier.copyTo(FieldModifier.java:79)
        at nl.jqno.equalsverifier.internal.reflection.InPlaceObjectAccessor.copyInto(InPlaceObjectAccessor.java:43)
        at nl.jqno.equalsverifier.internal.reflection.InPlaceObjectAccessor.copy(InPlaceObjectAccessor.java:24)
        at nl.jqno.equalsverifier.internal.checkers.ExamplesChecker.checkSingle(ExamplesChecker.java:84)
        at nl.jqno.equalsverifier.internal.checkers.ExamplesChecker.check(ExamplesChecker.java:47)
        at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verifyWithExamples(SingleTypeEqualsVerifierApi.java:413)
        at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.performVerification(SingleTypeEqualsVerifierApi.java:369)
        at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verify(SingleTypeEqualsVerifierApi.java:304)
        ... 1 more

Here's the class under test:

package a;

import java.util.Objects;

public class Dingetje {
    private final String text;

    public Dingetje(String text) {
        this.text = text;
    }

    @Override
    public final boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Dingetje)) {
            return false;
        }
        Dingetje other = (Dingetje) o;
        return text.equals(other.text);
    }

    @Override
    public final int hashCode() {
        return Objects.hash(text);
    }
}

And the test:

package a;

import nl.jqno.equalsverifier.EqualsVerifier;
import org.junit.jupiter.api.Test;

class DingetjeTest {
    @Test
    void implementsEquals() {
        EqualsVerifier.forClass(Dingetje.class)
                .withNonnullFields("text")
                .verify();
    }
}

What am I missing here?

Answer 1

EqualsVerifier uses Objenesis to create instances of classes, and it keeps the same reference of the objenesis object around for performance reasons. It caches all the objects it has created before, so that makes things quicker when you want to create the same object over and over again, which EqualsVerifier tends to do.

However, EqualsVerifier keeps a static reference to objenesis, which means that it lives as long as the JVM does. It turns out that the Quarkus test runner can re-run the same tests again and again, and it creates a new class loader each time. But part of the equality of java.lang.Class is that the classloader that created the class, must also be the same. So it couldn't retrieve these objects from its cache anymore and returnd instances with classloaders that are now different from the other objects created in the test, and this caused the exceptions that you saw.

In version 3.8 of EqualsVerifier (created as a result of this StackOverflow post), this issue can be avoided by adding #withResetCaches() like this:

EqualsVerifier.forClass(Dingetje.class)
    .withResetCaches()
    .withNonnullFields("text")
    .verify();

That fixes the problem.