# 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. *** ## 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. *** ## 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version 1.4.0 or higher is available when using merge mode, providing clear guidance if the dependency is missing or outdated.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 `` 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] --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://cover-docs-preview.diffblue.com/updates-and-upgrades/release-archive/2026-02-01.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.