> For the complete documentation index, see [llms.txt](https://cover-docs.diffblue.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cover-docs.diffblue.com/updates-and-upgrades/release-archive/2025-06-01.md).

# 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 `Optional`s. \[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]