In this release, Diffblue Cover now supports writing tests for Java 21 projects - Diffblue now supports LTS Java versions 8, 11, 17, and 21 in production use. Also, the release includes a significant update to the Cover Reports docs topics - https://docs.diffblue.com/features/cover-reports. See the full Release Notes below for details of all enhancements and resolved issues covered by this release.


  • Cover: Diffblue Cover now supports writing tests for Java 21 projects. [Ref: TG-20304]

  • CLI: Cover CLI now provides enhanced remediation advice for E011 - Failed to run a simple example test. [Ref: TG-19852]

  • Cover: Diffblue Cover now provides improved coverage when writing tests which use double/long/float constant comparisons. [Ref: TG-18581]

  • Plugin: Cover Plugin now creates run configurations when writing skeleton tests. [Ref: TG-17083]

Resolved Issues

  • Cover: Diffblue Cover now provides improved formatting for Javadoc comments when writing tests. [Ref: TG-20292]

  • Cover: Resolved an issue which caused Diffblue Cover to not write tests for inner classes containing a dollar sign, when executing a run configuration. [Ref: TG-19819]

  • Plugin: Resolved an issue which caused Cover Plugin to hang if a run configuration was executed during project indexing. [Ref: TG-19708]

Known Issues

  • Plugin: Cover Plugin incorrectly gives the option to write tests for a test file using the menu option, while in the IDE editor. [Ref: TG-17163]

  • Cover: Cover may produce tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

  • Cover: Diffblue Cover supports Open JDK and Oracle JDK; results with other JDKs may differ due to the variability in their implementations of Java. [Ref: TG-19345]

  • Cover: Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use a version of Mockito earlier than 5. [Ref: TG-19610]

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