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EqualsVerifier can be used in Java unit tests to verify whether the contract for the equals and hashCode methods is met.
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EqualsVerifier can be used in Java unit tests to verify whether the contract for the equals and hashCode methods in a class is met. The Maven coordinates are:


For documentation, please see the project's website.

Pull requests are welcome! If you open one, please also register an issue or send a message to the Google Group, so we can discuss it.


To build EqualsVerifier, you need Maven. Just call mvn clean verify from the command-line, and you're done. Alternatively, you can use any IDE with Maven support.

Project structure


  • nl.jqno.equalsverifier External API
  • nl.jqno.equalsverifier.internal Classes internal to the operation of EqualsVerifier
  • nl.jqno.equalsverifier.internal.checkers Checkers that perform EqualsVerifier's actual verifications
  • nl.jqno.equalsverifier.internal.exceptions Internally used exceptions
  • nl.jqno.equalsverifier.internal.prefabvalues Cache and factories for instances of all types
  • nl.jqno.equalsverifier.internal.reflection Helpers for reflection-based tasks
  • nl.jqno.equalsverifier.internal.util Various helpers


  • javax.persistence Annotations used by integration tests
  • nl.jqno.equalsverifier Unit tests for specific subcomponents of EqualsVerifier
  • nl.jqno.equalsverifier.coverage Code coverage tests, which fail if coverage is less than 100%
  • nl.jqno.equalsverifier.integration.basic_contract Integration tests that cover the contract as stated in java.lang.Object's javadoc
  • nl.jqno.equalsverifier.integration.extended_contract Integration tests that cover specific corner cases in the Java language, and other essential points that are discussed in other sources, such as Effective Java, but not in the javadoc
  • nl.jqno.equalsverifier.integration.extra_features Integration tests that cover non-standard situations that EqualsVerifier supports
  • nl.jqno.equalsverifier.integration.inheritance Integration tests that cover inheritance in equality relations
  • nl.jqno.equalsverifier.integration.operational Integration tests that cover issues that don't pertain to equals or hashCode themselves, but to EqualsVerifier's operation
  • nl.jqno.equalsverifier.testhelpers Utility classes for use in tests
  • nl.jqno.equalsverifier.testhelpers.annotations Annotations used by unit tests and integration tests
  • nl.jqno.equalsverifier.testhelpers.annotations.casefolding More annotations which would clash with other annotations because of casing
  • nl.jqno.equalsverifier.testhelpers.types Various data classes for use in unit tests and integration tests
  • nl.jqno.equalsverifier.util Unit tests for the reflection helpers


  • equalsverifier-signedjar-test.jar A local Maven repository containing a signed jar, used to test potential ClassLoader issues
    Here's how to install a jar into it:
    mvn org.apache.maven.plugins:maven-install-plugin:2.3.1:install-file \
                             -Dfile=<path-to-file> -DgroupId=<myGroup> \
                             -DartifactId=<myArtifactId> -Dversion=<myVersion> \
                             -Dpackaging=<myPackaging> -DcreateChecksum=true \
    The signed jar itself can be found in this repo.


Copyright 2009-2019 Jan Ouwens

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