> 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/2026-02-01.md).

# 2026-02-01

This release introduces a new merge mode (`--merge`) that integrates generated tests directly into existing test files, and adds support for Spring 7 and Spring Boot 4.

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## New Merge Mode

* **Direct Test Integration:** Diffblue Cover now supports merge mode (`--merge`), which integrates generated tests directly into existing `*Test.java` files instead of creating separate `*DiffblueTest` files. The `@WriteTestsTo` annotation allows for customizing test placement for specific classes. For more information, see the [Merge Mode documentation](https://docs.diffblue.com/features/cover-cli/writing-tests/merge-mode).

## Spring Framework Support

* **Spring 7 & Boot 4:** Diffblue Cover now supports Spring 7 and Spring Boot 4, enabling test generation for projects using the latest Spring framework versions.

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## Important Notices

### Upcoming: Checkstyle Compatibility in Merge Mode

In merge mode, checkstyle errors can occur if your project uses a formatter other than `google-java-format`. In an upcoming release, Cover will detect incompatible checkstyle configurations during environment checks and provide options to specify your project's formatter.

## Enhancements

* Diffblue Cover now supports merge mode (`--merge`), which integrates generated tests directly into existing `*Test.java` files instead of creating separate `*DiffblueTest` files. Use the `@WriteTestsTo` annotation to customize test placement for specific classes. \[Ref: TG-24165] [Docs](https://docs.diffblue.com/features/cover-cli/writing-tests/merge-mode)
* CLI: Diffblue Cover now consolidates `R090` output codes into a single message listing all affected classes, making merge failures easier to diagnose and resolve. \[Ref: TG-24164]
* Diffblue Cover now validates that `cover-annotations` version 1.4.0 or higher is available when using merge mode, providing clear guidance if the dependency is missing or outdated. \[Ref: TG-24163]
* Diffblue Cover now supports Spring 7 and Spring Boot 4, enabling test generation for projects using the latest Spring framework versions. \[Ref: TG-24162]
* Resolved an issue where Diffblue Cover would fail to parse Jacoco format configuration when `pom.xml` used nested `<format>` elements instead of comma-separated strings. \[Ref: TG-24160]

## Resolved Issues

* Resolved an issue where `dcover issues` would show accumulated output codes from previous modules when running on multi-module Maven projects. \[Ref: TG-24161]

## Known Issues

* Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. \[Ref: TG-17163]
* Using JDKs other than the supported Open JDK and Oracle JDK may produce unexpected results due to implementation differences. \[Ref: TG-19345]
* Cover may encounter an `F009` (Internal error) caused by a `ClassCircularityError` involving `org/mockito/configuration/MockitoConfiguration` when writing tests with Mockito 5. The recommended workaround is to downgrade to Mockito 4.x. \[Ref: TG-19610]
* Reports: The total line count metric in Reports only includes Java code. Kotlin code is not 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]
* 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' is malformed. \[Ref: TG-22805]
* When test formatting settings are changed, the Test Review feature may incorrectly remove the `@ManagedByDiffblue` annotation from tests, particularly in cases involving static import formatting changes. \[Ref: TG-23750]
* Plugin: Using the Test Review feature may create tests that have incompatible dependency injection systems. \[Ref: TG-23935]
* CLI: In rare circumstances, Cover may remove existing tests when using merge mode (`--merge`). The recommended workaround is to use the `@WriteTestsTo` annotation to specify a separate test class. \[Ref: TG-24166]