In this release, Diffblue Cover will write tests for all major versions of Java from 8-17. Diffblue only provides support for LTS versions 8, 11, and 17 in production use. Also, the release includes updates for Cover Reports, including the addition of the new --upload option to Cover CLI for uploading reports bundles, and an update to the install location. See the full Release Notes below for details of all enhancements and resolved issues covered by this release.


  • CLI & Reports: Report bundles can now be uploaded using the new --upload option from Cover CLI. Note that the --report option will be deprecated in a future release. [Ref: TG-20124]

  • Cover: Diffblue Cover now attempts to write tests for non-LTS and LTS Java versions (18, 19, 20, 21) if strict mode is not used. [Ref: TG-20049]

  • Plugin: Cover Plugin now provides an improved experience when writing tests for Java 17 Records. [Ref: TG-19891]

  • Cover: Diffblue Cover no longer warns about junit-vintage unless the --coverage-reports option is used. [Ref: TG-19770]

Resolved Issues

  • Reports: By default, Cover Reports will now be installed to a folder with no release number. Future upgrades will therefore overwrite the current install. [Ref: TG-20235]

  • CLI: Resolved an issue where in some circumstances running dcover clean may result in a NullPointerException. [Ref: TG-20174]

  • CLI: Resolved an issue where if --maven and --gradle are supplied at the same time, Cover CLI would display an incorrect error message. Cover now reports a clear message which states that these options are mutually exclusive, and to specify only one. [Ref: TG-20082]

  • Plugin: Resolved an issue where Cover Plugin could write tests for methods outside of the selection for multi-module projects. [Ref: TG-19744]

  • Plugin: Resolved an issue where in certain circumstances test links in Cover Plugin would not work correctly. [Ref: TG-18908]

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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