2025-06-01

2025-06-01

This release improves test generation, particularly for java.util.Optional and mock configurations. It also brings new CLI options for preflight checks and targeted JaCoCo coverage, alongside several key fixes and a new configuration warning.

• Test Generation & Quality:

  • New attributes for @InTestsMock allow specifying return values in mocked methods, yielding more domain-specific mock behaviors.

  • Improved test generation for java.util.Optional by better considering isPresent status, leading to more robust tests and coverage.

  • Fix for Mockito any() calls with bounded generic parameters now correctly uses wildcards, improving test compilation and coverage.

• CLI Enhancements & User Control:

  • New --new-jacoco-coverage option for dcover create solely writes tests that contribute new JaCoCo coverage, helping manage test volume.

  • Fix for environment summary not accurately reporting test validation status when disabled by an E022 error.

• Configuration & Plugin Usability:

  • New warning for configured test output directories not matching src/test/java, helping identify misconfigurations early.

  • Plugin fix: Unchecking "Override test directory" now correctly clears prior settings, and re-checking defaults to src/main/java.

Important Notices

Changes to test code

• Test formatting: In a future release, Cover will switch the default test formatting style to google-java-format. This will cause a one-time churn, resulting in larger-than-usual diffs in your test code. If you prefer a different style, an alternative formatter configured in your build system will override this new default.

Deprecated Features

• --existing-coverage option: The CLI option --existing-coverage for the dcover create command is deprecated as of release 2025.06.01 and is scheduled for removal in release 2025.06.02. This option was originally designed to use a JaCoCo file to guide test creation towards uncovered lines. To provide a more effective and streamlined experience for this functionality, it is being replaced. Users aiming to write tests focused on new coverage should now use the new --new-jacoco-coverage option, introduced in release 2025.06.01, which offers an enhanced and more direct approach.

Enhancements

• CLI: Diffblue Cover now displays a concise summary of environment checks if dcover remove is invoked with the --preflight option. This offers users a quick overview of prerequisites for the remove command. [Ref: TG-23186]

• CLI: Diffblue Cover now features the --new-jacoco-coverage option for the create command, allowing it to solely write tests that contribute new JaCoCo coverage. This helps manage the volume of tests by adding only those that expand coverage. [Ref: TG-23149]

• Diffblue Cover now issues a warning message if the configured test output directory is not src/test/java. This helps users identify potential misconfigurations before tests are created. [Ref: TG-23101]

• Diffblue Cover now provides new attributes for the @InTestsMock annotation, enabling users to specify return values for methods in mocked classes. This allows Diffblue Cover to generate tests with more domain-specific mock behaviors. [Ref: TG-23049]

• Diffblue Cover now writes tests with improved consideration for the isPresent status of java.util.Optional objects. This leads to better test generation and coverage for code involving Optionals. [Ref: TG-22868]

Resolved Issues

• Plugin: Resolved an issue where Diffblue Cover would use a previous override test directory value even if the "Override test directory" checkbox was unchecked. Unchecking now clears the prior setting, and re-checking defaults to "src/main/java". [Ref: TG-23191]

• Resolved an issue where Diffblue Cover sometimes wrote Mockito any() calls using an explicit object type instead of a wildcard for bounded generic parameters. This allows more generated unit tests to compile successfully, improving test coverage. [Ref: TG-23185]

• CLI: Resolved an issue where Diffblue Cover's environment summary did not properly reflect that test validation was disabled by an E022 error (JUnit Jupiter Launcher not found). This status is now accurately reported. [Ref: TG-21636]

Known Issues

• Plugin: Cover incorrectly provides a menu option to write tests for a test file. [Ref: TG-17163]

• 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]

• Reports: Cover only counts Java code towards the total line count metrics. Kotlin code is not currently included. [Ref: TG-22088]

• Reports: Total lines of code metric can incorrectly count a multi-line comment at the end of a line of code, resulting in fewer than expected lines counted. [Ref: TG-22089]

• Reports: Following an upgrade, the 'Total Lines of Code' card may show 0 until a new reports bundle has been uploaded. [Ref: TG-22094]

• In some circumstances, Cover may write more simplistic tests with less meaningful assertions when Spring Boot dependency injection is disabled. [Ref: TG-22102]

• In some circumstances, Cover will still write Spring Boot tests when Spring Boot dependency injection is disabled. [Ref: TG-22103]

• Cover may write failing TestNG tests when Spring Boot dependency injection is disabled. [Ref: TG-22107]

• Plugin: On some displays, the Test Review subsection title "Tests for review" can be malformed. [Ref: TG-22805]

• Cover does not currently support Java 24. Please switch your JDK version to 21 or lower. [Ref: TG-22920]