IntelliJ Plugin - automatic update to memory settings

The Diffblue Cover IntelliJ plugin requires 2GB of memory to run effectively. If you do not have enough memory available, Diffblue Cover now automatically adjusts your memory setting. You can undo this change (but please note that your IDE may be unstable without sufficient memory).

IntelliJ Plugin - suppressing warnings from SonarQube

Diffblue Cover writes tests that can be reported as “code smells” by SonarQube. By default, an option has been enabled in the Diffblue Cover IntelliJ plugin to add @SuppressWarnings to the start of each test, thus reducing the reported “code smells” in the SonarQube output. For more information, please see our documentation.

Support for Java 17 COMING SOON!

We have been working hard behind the scenes to get ready to support Java 17, and the work is nearly complete. We will have a full update next release!

Developer Edition trial available

We are delighted to now offer a 14-day trial version of our Developer Edition, which includes the Diffblue Cover CLI, as part of our new licensing option. We're really excited that you can now "try before you buy"! To download your trial of Diffblue Cover Developer Edition, please click here. Full information on all our options is also available here.

How do I automatically maintain all of these tests?

Use Diffblue Cover on any CI platform to automatically update your unit tests and catch regressions for every commit - watch this video to learn more.


  • Cover now has improved handling for broken .class files. [Ref: TG-16730]

  • Cover can now write tests which use singleton instance getters as inputs. [Ref: TG-16675]

  • Cover can now write tests which use inputs which extend Map, including org.apache.commons.chain.Command implementations. [Ref: TG-16673]

  • CLI: Cover now provides improved guidance when issues are encountered whilst writing tests for projects which have both Gradle and Maven build systems present. [Ref: TG-16619]

  • IntelliJ Plugin: Cover now automatically adjusts IntelliJ IDEA's 'maximum heap size' to ensure optimal test-writing performance. [Ref: TG-16671]

  • IntelliJ Plugin: Cover no longer writes tests which use mocks if Mockito is not on the classpath. Such tests would previously have caused compilation warnings in IntelliJ IDEA. [Ref: TG-16769]

  • IntelliJ Plugin: Cover now supports adding @SuppressWarning annotations to tests it writes when the option is enabled in the plugin settings. [Ref: TG-16618]

  • IntelliJ Plugin: Cover now creates more descriptive run configuration names when tests are written for multiple items. [Ref: TG-16552]

Resolved Issues

  • Resolved an issue which, in some circumstances, would cause F009 (Internal error) to be reported when applying mocks. [Ref: TG-14987]

  • Resolved an issue which caused F009 (Internal Error) comments to appear in tests written for Spring projects with XML configurations containing abstract beans. [Ref: TG-16735]

  • Resolved an issue which, in some circumstances, would cause R005 (Unable to load class) to be reported for classes that are actually present on the classpath and can be loaded. [Ref: TG-16711]

  • CLI: Resolved an issue which, when no manual tests are present, caused dcover create --coverage-reports to abort rather than creating a coverage report for the tests written by Cover. [Ref: TG-16739]

  • IntelliJ Plugin: Resolved an issue which, in some circumstances, could provoke an internal error while creating report.json. [Ref: TG-16554]

Known Issues

  • CLI: The command dcover clean --failing does not work on Gradle projects. This command is now deprecated and dcover validate should be used instead. [Ref: TG-11707]

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