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]

• Descriptive Test Naming: In a future release, Cover will default to writing tests which use descriptive Given-When-Then-style names. For more details on Descriptive Test Naming (beta), please refer to the IntelliJ Plugin documentation or the Cover CLI documentation.

Enhancements

• Cover now supports JUnit Jupiter 5.11.1. [Ref: TG-22087]

• Cover now writes tests which assert on Iterator objects. [Ref: TG-22079]

• Cover now supports Maven 3.9.9. [Ref: TG-22039]

• CLI: Cover now provides the ability to specify which modules to run CLI commands on via the --include-modules option or DIFFBLUE_INCLUDE_MODULES environment variable. [Ref: TG-22019]

• Cover now provides improved messaging related to interactions with the project's build system. [Ref: TG-21996]

• Reports: Metric labels have been adjusted to be more consistent and accurate. [Ref: TG-21710]

• Reports: Improved overview cards, providing new metrics for manual test count, total lines of code, covered and uncovered lines. [Ref: TG-21708]

• Reports: Updated logo and color scheme. [Ref: TG-21700]

• Cover now provides an option to disable Spring Boot dependency injection (@MockBean) in favor of other dependency injection mechanisms, such as Mockito's @InjectMocks and @Mock. [Ref: TG-21467]

• CLI & Reports: Cover now provides improved remediation advice when a JaCoCo report cannot be produced to due non-compiling tests. [Ref: TG-19166]

Resolved Issues

• Resolved an issue which caused Cover to produce broken Javadoc links to default constructors with Descriptive Test Naming enabled. [Ref: TG-22012]

• Resolved an issue which, in some circumstances, caused Cover to write tests which assert on an internal PrintWriter object. [Ref: TG-21959]

• Resolved an issue which caused Cover to report F009 (Internal Error) when it failed to create a Spring context due to missing Spring beans. [Ref: TG-21931]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

• 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]

Updated Test Creation Limits for Diffblue Cover

As of the 2025.02.01 release, we've updated how test creation limits work for Diffblue Cover to give you more predictable and manageable usage. These changes apply only to Community Edition and Developer Edition. Teams and Enterprise editions are unaffected.

What's Changed

• Test creation limits are now based on methods tested, not individual tests written.

• You will incur consumption for each method for which a new test is successfully produced. This means you have a clearer understanding of your limit usage before clicking 'write tests'.

• Consumption is calculated based on the number of new methods covered by generated tests, regardless of how many tests are produced for a single method.

• When Cover Plugin's 'Test Review' feature is enabled, quota consumption will still occur for methods with newly generated tests even if they are not "accepted".

Monthly Limits

• Community Edition: 25 methods per month

• Developer Edition Basic: 100 methods per month

• Developer Edition Pro: 200 methods per month

• Developer Edition Ultra: 400 methods per month

Diffblue Cover is now generally available to individual developers and small teams.

We've just launched our Developer Edition license. From today, individual developers can leverage the power of AI they can trust for unit test generation and maintenance.

Enhancements

• CLI: Cover now provides clearer messages if test validation takes too long. Instead of indicating a failed coverage calculation, it guides users to adjust the TIMEOUT setting in DiffblueBuild.yaml. [Ref: TG-22629]

• Cover now generates a template DiffblueBuild.yaml file for Ant projects when using dcover build-default-config --ant. The template includes essential configurations and inline customization guidance, simplifying setup. [Ref: TG-22602]

• Plugin: The "Update Test" functionality now uses the @MethodsUnderTest test annotation for accurately identifying Methods Under Test (MuTs). Please avoid modifying this annotation. [Ref: TG-22462]

• CLI & Plugin: Cover now counts methods tested instead of tests created. This affects Community Edition, Developer Edition, and Teams Trial users. [Ref: TG-21883]

• CLI: dcover validate now handles validation errors more precisely. Instead of discarding entire test classes due to issues in a subset of tests (compilation or assertion failures), it discards only the failing tests, preserving the rest. [Ref: TG-20316]

Resolved Issues

• CLI: Resolved an issue where Cover incorrectly generated @AfterMethod methods for TestNG, preventing proper reset of mocks and the target object. [Ref: TG-22632]

• Resolved an issue which could cause Cover to incorrectly mock String values as dependencies, potentially leading to invalid test code such as @MockBean private String string. [Ref: TG-22523]

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]

• Test Method Ordering: In an upcoming release, Cover will adjust test method ordering and imports for inner classes. This will cause a one-time churn, resulting in larger-than-usual diffs in your test code.

• Test Method Tagging: In an upcoming release, tests created by Cover will be annotated with a MaintainedByDiffblue label. This will cause a one-time churn when recreating test, resulting in larger-than-usual diffs in your test code. This will enable Cover to combine Diffblue tests and manually written tests into the same test classes.

Requirements

• JUnit 4: Users of JUnit 4 will soon require the use of the cover-annotations library version 1.3.0+ in order for coverage to be calculated correctly. This will be part of Test Method Tagging.

Diffblue Cover is now generally available to individual developers and small teams.

We've just launched our Developer Edition license. From today, individual developers can leverage the power of AI they can trust for unit test generation and maintenance.

Enhancements

• Cover now supports Jupiter 5.11.4. [Ref: TG-22497]

• Reports: Telemetry page performance improvements. [Ref: TG-22415]

• Plugin: Cover now allows the Test Review window to be expanded/docked for easier test diff reviewing. [Ref: TG-22378]

• CLI: Cover now allows excluding methods from being called in tests by using the --exclude-method option. [Ref: TG-22235]

Resolved Issues

• Plugin: Resolved an issue which prevented the 'What's New' page from loading on Windows following an upgrade. [Ref: TG-22495]

• Resolved an issue which caused Cover to report R026 while writing tests due to custom base classes not being considered. [Ref: TG-22341]

• Plugin: Resolved an issue which caused cover to show 'delete test' gutter icons on non-test methods. [Ref: TG-22177]

• Resolved an issue which caused Cover to write non-compiling tests for overloaded methods with variadic parameters (varargs). [Ref: TG-21835]

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]

Framework Support & Compatibility

• Mockito 5.20.0 Support: Diffblue Cover now supports Mockito Core version 5.20.0, ensuring full compatibility for tests generated in projects that use this version of the mocking framework.

Enhancements

• Diffblue Cover now supports Mockito Core version 5.20.0, ensuring test compatibility for projects using this version. [Ref: TG-23807]

• Diffblue Cover now generates higher quality tests for projects using javax.servlet. Adding the spring-test dependency produces more effective tests by using Spring's MockHttp classes to accurately simulate HTTP requests and responses. [Ref: TG-23095]

• Diffblue Cover now supports the @InTestsUseFactories annotation to provide more precise control over test inputs. This annotation guides test generation by specifying which factory methods Cover must use to create objects for a given test. [Ref: TG-21232]

Resolved Issues

• Resolved an issue that caused Cover to report R011 or R081 output codes when writing tests for code using log4j or Mockito. These failures were due to sandbox policy violations during localhost resolution. [Ref: TG-23827]

• Resolved an issue that limited assertDoesNotThrow test cases. Diffblue Cover now writes these assertions for any validation method, not just those named 'validate', improving test coverage for methods that do not follow a specific naming convention. [Ref: TG-23762]

• Resolved a test generation failure (F009) that occurred when a method from an instance was referenced multiple times within the method under test. This fix applies to instances created with a parameterized constructor or a factory. [Ref: TG-23416]

Known Issues

• Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. [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]

• 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: 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]

• 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]

Resolved Issues

• Resolved an issue which caused Cover to report a custom validation command failure when running dcover validate within an IntelliJ IDEA terminal. [Ref: TG-21522]

• Plugin: Resolved an issue where, in certain circumstances, writing Java tests for Kotlin code caused Cover to create non-compiling tests. [Ref: TG-20759]

Known Issues

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

• CLI & Plugin: Cover may write tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• 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]

• In rare circumstances 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]

Resolved Issues

• Cover: Diffblue Cover now provides improved formatting for Javadoc comments when writing tests. [Ref: TG-20292]

• Cover: Resolved an issue which caused Diffblue Cover to not write tests for inner classes containing a dollar sign, when executing a run configuration. [Ref: TG-19819]

• Plugin: Resolved an issue which caused Cover Plugin to hang if a run configuration was executed during project indexing. [Ref: TG-19708]

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]

• IntelliJ IDEA 2023.3: With the introduction of support for IntelliJ IDEA 2024.2, support for IntelliJ IDEA 2023.3 has been removed in this release.

Enhancements

• CI: Commit messages made by Cover Pipeline now include the Diffblue Cover version used to write tests. [Ref: TG-21821]

• Reports: Reports bundles can now be produced and uploaded to Cover Reports using coverage-reports without needing to run test generation via create. Cumulative test counts will be shown on the overview as a 'Number of Diffblue Tests' card. [Ref: TG-21789]

• CLI: Diffblue Cover Pipeline now supports running in any CI/CD environment using git version control. [Ref: TG-21788]

• Cover now writes tests with more concise assertions for StringWriter(). [Ref: TG-21715]

• Cover now writes tests faster, with up to 10x speed improvements for projects which use Apache Flink. [Ref: TG-21656]

• Cover now has improved method-under-test analysis, resulting in tests being written with more valuable assertions. [Ref: TG-21608]

• Plugin: Cover now supports IntelliJ IDEA Community Edition 2024.2 and IntelliJ IDEA Ultimate 2024.2. Support for IntelliJ IDEA 2023.3 has been removed. [Ref: TG-21423]

• Plugin: Cover's tool panel window has been redesigned. When writing tests, Cover will now display visual cards containing the count of tests created, as well as the count of pending methods under test. [Ref: TG-21289]

Resolved Issues

• Resolved an issue which, in some circumstances, could cause F009 (Internal Error) to be reported while writing tests where Spring XML configurations are used. [Ref: TG-21813]

• Resolved an issue which caused Cover to not provide the most useful and informative Spring error message when encountering R026 (Failed to create Spring context). [Ref: TG-21744]

• Plugin: Resolved an issue which, in some circumstances, could cause Cover to get stuck at the 'Checking environment' phase. [Ref: TG-21604]

• CLI & Plugin: Resolved an issue which, in some circumstances, caused Cover to report an incorrect output code and remediation advice, when using an unsupported version of JUnit [Ref: TG-21564]

• CLI: Resolved an issue where Cover did not detect all the projects with identical names from a Gradle multi-project build. Cover now identifies the Gradle sub-projects by their path. This affects the arguments passed to the --exclude-modules. [Ref: TG-21052]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

Enhancements

• Plugin: Cover now supports IntelliJ IDEA Community Edition 2024.2 and IntelliJ IDEA Ultimate 2024.2. [Ref: TG-21658]

• Cover now writes more tests in situations where Spring contexts get dirtied. [Ref: TG-21587]

• Cover now writes tests which do not redundantly assert on toString() when already asserting on .pattern(). [Ref: TG-20806]

• Cover now writes tests with improved assertions by using toByteArray when writing tests for methods which use ByteArrayOutputStream. [Ref: TG-20805]

Resolved Issues

• Plugin: Resolved an issue which caused Cover to not invalidate the environment check cache after changing the JDK at the module or project level. [Ref: TG-21670]

Known Issues

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

• CLI & Plugin: Cover may write tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• 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 may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

Resolved Issues

• Plugin: Resolved an issue where using 'Restart' in the Diffblue tool panel after adding a dependency with 'Fix Issues' at the package level would cause it to hang on the 'Preparing' phase. [Ref: TG-21382]

• Resolved an issue which, in some circumstances, caused Cover to report an F009 (Internal Error) while writing tests for methods with functional arguments. [Ref: TG-21335]

• Resolved an issue which, in some circumstances, caused Cover to write non-compiling tests for methods with multiple functional arguments. [Ref: TG-21334]

• CLI: Resolved an issue which caused Cover to report Unexpected licensing exception when activating with an invalid offline license activation file. [Ref: TG-21329]

• CLI: Resolved an issue which caused Cover to report L024: Unexpected licensing exception when attempting to activate a license with a activation start date in the future. [Ref: TG-20957]

Known Issues

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

• CLI & Plugin: Cover may write tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• 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 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]

• Under some circumstances, when writing Java tests for Kotlin code, Cover may produce non-compiling tests. [Ref: TG-20759]

Resolved Issues

• Cover: Resolved an issue where Diffblue Cover could not write tests because it encountered an infinite loop in the method under test. [Ref: TG-19702]

• Cover: Resolved an issue which caused Diffblue Cover to suggest incompatible JUnit dependencies. [Ref: TG-19659]

• Plugin: Resolved an issue where tests in Gradle multi-module projects could be written into the wrong module. [Ref: TG-19606]

• Cover: Resolved an issue where tests were always written in UTF-8 and not the project's configured character encoding. [Ref: TG-19556]

• CLI & Reports: Resolved an issue which caused Cover CLI to report an internal server error when uploading a reports bundle created using a JaCoCo Plugin version older than 0.8.2. Cover now requires 0.8.2 or above when creating reports bundles. [Ref: TG-19546]

Known Issues

• 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 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]

Resolved Issues

• CLI & Plugin: Resolved an issue which caused Cover to write tests with unused getter calls. [Ref: TG-21139]

• CLI: Resolved an issue which caused Cover to not warn, during preflight, about incompatibility between Spring Core and javax.servlet when using javax.servlet 2.3, 2.4 or 2.5. [Ref: TG-21131]

• CLI: Resolved an issue which caused Cover to report Failed to find git executable while using dcover upload without git available on the path. [Ref: TG-21101]

• Plugin: Resolved an issue which, in some circumstances, caused Cover to report Diffblue Cover was unable to start its analysis service [...] while identifying Spring XML configuration files. [Ref: TG-21097]

• Reports: Resolved an issue which caused Cover Reports to show Unexpected Application Error if all projects are removed. [Ref: TG-21075]

• Reports: Resolved a cosmetic issue which could cause table header sorting indicators to not represent the current sorting order. [Ref: TG-21056]

• Reports: Resolved a cosmetic issue which caused table headers to become misaligned after using the sorting options. [Ref: TG-21055]

• CLI: Resolved an issue which, in some circumstances, prevented preflight from providing a list of existing non-Diffblue tests which failed to run. [Ref: TG-19884]

• Plugin: Resolved an issue which, in some circumstances, caused tests to be written with incorrect formatting. All tests written by Cover now match the project's formatting rules. [Ref: TG-18153]

Known Issues

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

• CLI & Plugin: Diffblue Cover may write tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• CLI & Plugin: 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]

• CLI & Plugin: 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]

• Plugin: Under some circumstances, when writing Java tests for Kotlin code, Cover may produce non-compiling tests. [Ref: TG-20759]

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]

• Test Method Ordering: In an upcoming release, Cover will adjust test method ordering and imports for inner classes. This will cause a one-time churn, resulting in larger-than-usual diffs in your test code.

Diffblue Cover is now generally available to individual developers and small teams.

We've just launched our Developer Edition license. From today, individual developers can leverage the power of AI they can trust for unit test generation and maintenance.

Enhancements

• Plugin: Cover now provides a status bar widget which, when clicked, displays an overview of current license consumption and details. [Ref: TG-22127]

Resolved Issues

• Resolved an issue which, in some circustances, caused Cover to incorrectly insert // Assert that nothing has changed comments into tests. [Ref: TG-22437]

• Plugin: Resolved an issue which could, in certain circumstances, display an error after clicking "Fix issue" for a small heap size in the Environment Checks window. [Ref: TG-22400]

• CLI & Reports: Resolved an issue which caused cumulativeDiffblueTestCount and cumulativeManualTestCount to be incorrectly counted for TestNG projects. [Ref: TG-22333]

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]

Resolved Issues

• Reports: Resolved an issue, in the administrator view, which prevented moving a project group to the root of the hierarchy. [Ref: TG-21015]

• Plugin: Resolved a cosmetic issue which caused a scroll bar to appear on the 'Community Edition license created' screen when IntelliJ's zoom was set higher than 100%. [Ref: TG-20942]

Known Issues

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

• Cover: Diffblue 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]

• Plugin: Under some circumstances, when writing tests at a Class level, Cover will delete an existing getter test. [Ref: TG-20611]

• Plugin: Under some circumstances, when writing Java tests for Kotlin code, Cover may produce non-compiling tests. [Ref: TG-20759]

Resolved Issues

• CLI: Resolved an issue which caused Cover to report Built when running dcover build even if the build failed. [Ref: TG-22202]

• Resolved an issue which caused Cover to write tests, which require a Jackson ObjectMapper, using a new ObjectMapper() which has no optional modules configured. Cover now discovers existing instances or configures one with all available modules. [Ref: TG-22150]

• CLI: Resolved an issue which, in some circumstances, caused Cover to report Unresolved compilation problem. [Ref: TG-22141]

• Plugin: Resolved an issue which caused IntelliJ to report an error after clicking 'Accept All' in the test review panel while writing tests. [Ref: TG-21938]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

• 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]

Resolved Issues

• Plugin: Resolved an issue which, in some circumstances, caused test writing to be delayed during the preparation phase. [Ref: TG-21903]

• Cover + Reports: Resolved an issue which, in some circumstances with mismatched versions, caused large quantities of log messages to appear in log files. [Ref: TG-21752]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

Resolved Issues

• Resolved an issue which, in some circumstances, prevented tests being written for methods which take Class objects with nested generics. [Ref: TG-21847]

• Resolved an issue which, in some circumstances, caused tests written for Thread extension classes to be removed during verification. [Ref: TG-21584]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

In this release, we have standardized the Mockito versions supported by Diffblue Cover. This, and other useful information, is shown in our Datasheet:

| Java Version | Supported Mockito Versions |

| --- | --- |

| 17 | 4.1.0 - 4.7.0 |

| 11 | 2.22.0 - 4.7.0 |

| 8 | 1.9.5 - 4.7.0 |

​​​​​

Developer Edition trial available

We are delighted to now offer a 14-day trial version of our Developer Edition, which includes the Diffblue Cover CLI, as part of our new licensing option. We're really excited that you can now "try before you buy"! To download your trial of Diffblue Cover Developer Edition, please click here. Full information on all our options is also available here.

How do I automatically maintain all of these tests?

Use Diffblue Cover on any CI platform to automatically update your unit tests and catch regressions for every commit - watch this video to learn more.

Immutables Library: Resolved an issue to ensure that Diffblue Cover now correctly writes tests for methods that use objects from the 'immutables' library.

Performance & Stability

• Performance with Threads: Corrected a performance issue by ensuring user-created Java threads and Timers are properly shut down during analysis, preventing resource leaks and improving speed.

• CLI Memory Checks: The CLI now checks for sufficient JVM heap space and provides a clear warning if memory is insufficient, preventing silent failures.

• CLI Test Validation: Resolved an issue in Gradle projects using JUnit 5 where test validation could incorrectly remove entire test classes. Validation is now more precise and only removes failing tests as intended.

Improved Test Generation & Coverage

• Collection & Map Fields: Test coverage is improved for methods that modify collection and map fields, such as those using add() or put() to populate data structures.

• Final Classes: Diffblue Cover now writes tests for code that interacts with final classes by automatically generating the necessary mocks.

• Validation Methods: Test writing for void validation methods has been enhanced. Cover now writes tests for the successful execution path in addition to the existing exception-throwing path.

Important Notices

• Removal of IntelliJ 2024.3 Support: Support for the IntelliJ 2024.3 platform has ended. To use Diffblue Cover plugin version 2025.08.01 onwards, users must upgrade their IDE to IntelliJ version 2025.1 or 2025.2.

• IntelliJ Plugin: Removal of Support for JUnit 5.0-5.2: Following the deprecation in 2025.07.02, support for JUnit 5.0.x, 5.1.x, and 5.2.x has now been removed from the IntelliJ plugin. To ensure compatibility with this release and future versions, projects using these older versions must be upgraded to 5.3.0 or higher. This change does not affect projects using JUnit 4 or TestNG, nor does it impact the Diffblue Cover CLI.

Forthcoming Changes

• Improved Test Readability: In an upcoming release, Cover will instantiate data-holding classes (e.g., JPA entities) directly instead of using mocks where possible. While this produces higher quality tests, please be aware that existing tests for affected classes will change, leading to noticeable changes in your test suite upon update.

Enhancements

• CLI: To prevent silent failures from low memory, Diffblue Cover now checks for sufficient JVM heap space earlier. Users now receive a clear warning with the required minimum value if memory is insufficient, improving diagnostic feedback. [Ref: TG-23607]

• Diffblue Cover now generates tests with improved coverage for methods that modify collection and map fields. This enhances test creation for classes that use methods like add() or put() to populate internal data structures. [Ref: TG-23534]

• Plugin: Diffblue Cover now provides full support for the IntelliJ 2025.2 platform, ensuring compatibility with the latest IDE features. Support for IntelliJ 2024.3 has been discontinued; an upgrade to 2025.1 or 2025.2 is required for plugin use. [Ref: TG-22565] Docs

• Diffblue Cover now writes tests for code interacting with final classes by generating the necessary mocks, increasing the scope of testable code. [Ref: TG-22046]

Resolved Issues

• Resolved an issue where Diffblue Cover would not use the generated builder for classes annotated with @Immutable.Value from the 'immutables' library. Diffblue Cover now correctly writes tests for methods that use Immutable objects. [Ref: TG-23586]

• Resolved an issue where Diffblue Cover would only write tests for void validation methods that throw exceptions. Diffblue Cover now also writes tests for the successful execution path of these methods, ensuring validation logic is more thoroughly tested. [Ref: TG-23584]

• CLI: Resolved an issue where Diffblue Cover could exit prematurely or incorrectly remove entire test classes during test validation in Gradle projects using JUnit 5. Validation is now more precise, removing only failing tests as intended. [Ref: TG-23410]

• Resolved a performance issue during test generation for code that creates Java threads or Timers. Diffblue Cover now correctly shuts down these user-created threads, preventing resource leaks and improving analysis speed. [Ref: TG-23384]

Known Issues

• Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. [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]

• Cover may encounter an F009 (Internal error) caused by a ClassCircularityError involving org/mockito/configuration/MockitoConfiguration when writing tests with Mockito 5. To avoid this, use an earlier version of Mockito. Downgrading to Mockito 4.x is the recommended workaround. [Ref: TG-19610]

• 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]

• Diffblue Cover does not currently support test creation for projects using Java 24; please use JDK 21 or lower. [Ref: TG-22920]

Performance & Usability

• Faster CLI Performance: Test creation using the CLI is now significantly faster for Maven projects, especially multi-module projects. When a prefix entry point is used, Cover now also performs automatic module selection, removing the need for the --include-modules argument.

• IntelliJ Plugin Fix: Resolved an issue in the IntelliJ Plugin where the 'Update test' gutter icon could fail to start a test update operation.

Improved Test Quality & Management

• Disabled Test Class Handling: When merging tests, Diffblue Cover now prevents adding new tests to disabled test classes. This change avoids generating tests that would not run and instead reports an output code (R089) for the affected class.

• Test Review Annotation: Resolved an issue in the Test Review feature where formatting-only edits caused Diffblue Cover to remove the @ManagedByDiffblue annotation. This ensures that tests remain managed by Cover unless substantive code changes are made.

Important Notices

Prerequisite: Project Compilation

Due to recent build system optimizations, building your project remains an essential prerequisite for running Diffblue Cover. A compiled project is required for Cover to analyze code and generate tests successfully.

For detailed instructions, see the documentation for building a Maven project and a Gradle project.

Enhancements

• CLI: Diffblue Cover now provides significant speed improvements for multi-module projects when a prefix entry point is used. Module selection is now automatic in this scenario, removing the need to specify the --include-modules CLI argument. [Ref: TG-23781]

• Diffblue Cover no longer adds new tests to disabled test classes when merging tests. Instead, it reports an error (R089) for the affected class. [Ref: TG-23744]

• CLI: Diffblue Cover now runs significantly faster when creating tests for Maven projects. Users with multi-module projects will see the most noticeable performance improvements when using CLI commands like dcover create. [Ref: TG-23714]

• Diffblue Cover now supports test generation for OSGi applications and automatically uses the org.osgi.service.component.annotations dependency, when available, to improve test coverage. [Ref: TG-23699]

• Diffblue Cover now provides experimental test writing support for applications built with Java 24 and Java 25. Full support continues for Java versions 8, 11, 17, and 21. [Ref: TG-22920]

Resolved Issues

• Plugin: Resolved an issue in the IntelliJ Plugin where the 'Update test' gutter icon could fail to start a test update operation in certain edge cases. [Ref: TG-23748]

• Resolved an issue in the Test Review feature where formatting-only edits caused Diffblue Cover to remove the @ManagedByDiffblue annotation. This ensures that tests remain managed by Diffblue Cover unless substantive code changes are made by the user. [Ref: TG-23738]

Known Issues

• Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. [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]

• 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: 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]

• 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]

Important Notices

CLI: Deprecation of Build System Customization Options

As of the 2025.02.02 release, the following CLI options have been marked as deprecated:

• --build-system-configuration

• --ignore-stylechecks

• --jacoco-command-diffblue

• --jacoco-command-manual

• --jacoco-xml-test-report

• --preflight-test-command

• --preflight-test-timeout

• --validation-timeout

• --validation-command

Migrating to a DiffblueBuild.yaml file is recommended for build system integration. See the configuration guide for more details.

Enhancements

• Plugin: Cover now supports IntelliJ IDEA Community Edition 2025.1 and IntelliJ IDEA Ultimate 2025.1 EAP. [Ref: TG-22574]

• Plugin: Cover now displays a list of test methods in the Test Review panel. This allows for easier navigation through tests requiring review, grouped by method-under-test. The list will not appear if descriptive test names are disabled. [Ref: TG-22376]

• Reports: Tests tagged with MaintainedByDiffblue, in any test files, now count towards the 'Diffblue coverage' statistic shown in Cover Reports. [Ref: TG-21447]

• Plugin: Cover's Test Review feature is now enabled by default. Tests must be accepted manually before appearing in your codebase. Test Review can be disabled via the plugin settings dialog. [Ref: TG-21297]

• CLI & Plugin: Diffblue Cover now writes tests with improved branch coverage for code comparing enums by name. [Ref: TG-20568]

Resolved Issues

• Resolved an issue which caused Cover to recommend incorrect cover-annotations dependency scope: it now recommends provided (Maven) or compileOnly (Gradle). [Ref: TG-22749]

• CLI & Plugin: Cover now provides a warning (E154) and remediation advice if PowerMock and Mockito artefacts conflict. Conflicting artefacts can cause Cover to write fewer tests. [Ref: TG-21209]

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]

Resolved Issues

• Resolved an issue which, in some circumstances, caused Cover to report spring-boot-starter-webflux as a missing dependency despite the project not containing Reactive controllers. [Ref: TG-21129]

• Reports: Resolved an issue which, in some circumstances, caused tables to duplicate rows after changing the sorting order via column headings. [Ref: TG-21068]

• Reports: Resolved an issue which, in some circumstances, caused <root> to be shown in the recent projects list [Ref: TG-21061]

• Reports: Resolved an issue which, in some circumstances, caused an error to be displayed after navigating to the home screen while the coverage details tab is open. [Ref: TG-21060]

• Reports: Resolved an issue which caused deleted projects to be visible in the recent projects list. [Ref: TG-21025]

• CLI: Cover's environment summary output now reports Warning, rather than Success, for the 'Test Validation' row when Test Validation has been disabled by the user. [Ref: TG-20857]

• Resolved an issue which caused Cover to, in some circumstances, discard tests written for methods which spawn threads. Cover now reports R011 (Sandboxing policy violation) when encountering methods which provoke sandboxing policy violations in a thread. [Ref: TG-20525]

Known Issues

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

• Cover: Diffblue 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]

• Plugin: Under some circumstances, when writing Java tests for Kotlin code, Cover may produce non-compiling tests. [Ref: TG-20759]

Deprecations

• JUnit 4.7-4.10: Deprecated in a previous release. Please upgrade to JUnit 4.11 or higher to avoid future compatibility issues. Support for JUnit 4.7-4.10 will be removed in a future release.

Removals

• CLI --project option: Deprecated in a previous release and removed in this release. Please use --project-name and --location options instead. For more details, refer to the Generate and upload reports bundles documentation.

Enhancements

• Cover now produces assertions for base class getters when writing tests for simple constructors. [Ref: TG-21562]

• Cover now provides more detailed information and remediation advice when the internal analyzer process fails to start up. [Ref: TG-21341]

• Cover now makes better decisions about which inputs to assert on. [Ref: TG-21246]

• CLI: Cover's dcover build command now shows build progress when building multiple modules. [Ref: TG-21198]

• Cover now writes tests with more concise assertions for StringBuffer, StringBuilder, URL, URI and UUID types. [Ref: TG-20803]

• Cover now writes tests which reuse existing objects for method references, avoiding the creation of new objects. [Ref: TG-20690]

• Cover now writes tests that reference Consumer and Supplier types. [Ref: TG-20685]

Resolved Issues

• Resolved an issue which caused Cover to write tests with unused statements inside StepVerifier lambdas. [Ref: TG-21565]

• CLI: Resolved an issue which, in some circumstances, prevented Cover from identifying modules in a multi-module Maven project when the root module was not a parent of the other modules. [Ref: TG-21544]

• Reports: Updated to Spring Boot 3 and Spring 6 to remove a vulnerability. Cover Reports now requires an environment with Java 17. [Ref: TG-20973]

• Resolved an issue which, in some circumstances, caused Cover to assert on the size of a changed collection, rather than the contents. Cover now uses assertSame in these scenarios. [Ref: TG-20234]

Known Issues

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

• CLI & Plugin: Cover may write tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• 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]

• In rare circumstances 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]

• Under some circumstances, when writing Java tests for Kotlin code, Cover may produce non-compiling tests. [Ref: TG-20759]

Resolved Issues

• CLI & Plugin: Resolved an issue which caused Diffblue Cover to report R026: Failed to create Spring context if the Scala standard library is in use. [Ref: TG-19448]

• CLI: Resolved an issue which caused Diffblue Cover to report F009: Internal error when providing an invalid Cover Reports server location. Diffblue Cover now reports E138: Unable to convert path to URL. [Ref: TG-19400]

• Reports: Resolved a minor issue with the page navigation on the Projects page. [Ref: TG-19375]

• Optimize: Resolved an issue which caused Diffblue Cover to log a NullPointerException when using a patch which contains a file path which cannot be found. Diffblue Cover now reports E124: Referenced file in patch file not found. [Ref: TG-19373]

• CLI & Plugin: Improved E013: Compatible launcher not found output code messaging (JUnit Jupiter Launcher and JUnit Jupiter Engine version compatibility). [Ref: TG-19338]

• Cover: Improved L024: Unexpected licensing exception output code messaging (licensing server connection). [Ref: TG-19280]

• CLI & Plugin: Introduced a recommendation to avoid JUnit 4.11 and below when using JUnit Vintage Engine. Also recommend to avoid JUnit Vintage Engine when JUnit 5 is not present. [Ref: TG-19220]

Known Issues

• Cover may produce tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• IntelliJ Plugin: Upgrading to IntelliJ IDEA 2022.3 may, in some circumstances, cause existing run configurations to no longer produce tests. Removing any run configurations for that entity and writing tests again will recreate a working run configuration [Ref: TG-18282]

Resolved Issues

• CLI: Resolved an issue which caused Diffblue Cover to disable test verification when --skip-test-validation was specified. [Ref: TG-19217]

• CLI & Plugin: Resolved an issue which caused Diffblue Cover to write tests using mocking for POJO-like interfaces where a suitable implementation was available. [Ref: TG-19161]

• CLI & Plugin: Resolved an issue which, in some circumstances, caused Diffblue Cover to write unused when .. thenReturn mocks which could cause an UnnecessaryStubbingException. [Ref: TG-19113]

• CLI & Plugin: Resolved an issue which could cause Diffblue Cover to report an incorrect version of junit-vintage-engine detected in the user's environment. [Ref: TG-19335]

• CLI & Plugin: Fixed an issue where Diffblue Cover could not use MockitoJUnitRunner in tests with Mockito 2.22.0+. Also fixed an issue where Diffblue Cover would attempt to use MockitoExtension when it was not on the classpath which resulted in fewer tests. [Ref: TG-19111]

• CLI & Reports: Resolved an issue which caused Diffblue Cover CLI to report E098 while uploading a reports bundle containing inconsistencies. Diffblue Cover now uploads the bundle successfully and logs the inconsistency. [Ref: TG-19326]

• Reports: Resolved an issue which, in some circumstances, caused Diffblue Cover to incorrectly report lines which are excluded by Diffblue Cover and those that are not covered. Upgrade to 2023.06.02 and upload a new reports bundle to correct any previously inaccurate counts. [Ref: TG-19363]

• Reports: Resolved an issue which caused Diffblue Cover to sort dates incorrectly on telemetry dashboards. [Ref: TG-19189]

• Optimize: Resolved an issue where executing dcover optimize --patch-file=patch.file may result in unexpected, unhandled exceptions in Windows. [Ref: TG-19348]

Known Issues

• CLI & Plugin: Diffblue Cover may produce tests for JUnit 4.10 and lower that do not compile due to the use of assertNotEquals. [Ref: TG-17605]

• IntelliJ Plugin: Upgrading to IntelliJ IDEA 2022.3 may, in some circumstances, cause existing run configurations to no longer produce tests. Removing any run configurations for that entity and writing tests again will recreate a working run configuration. [Ref: TG-18282]

Cover: Cover now attempts to find methods in the tested class as Predicate/Function parameters for the tested method. If none are found, it reverts to using mocked values. [Ref: TG-20318]

Resolved Issues

• CLI: Resolved an issue which caused Cover CLI to report E014 - No build system found when using --classpath without Maven or Gradle present. [Ref: TG-20674]

• CLI: Resolved an issue which under some circumstances caused Cover CLI to display the incorrect upload URL when uploading reports bundles. [Ref: TG-20439]

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]

• Plugin: Under some circumstances, when writing tests at a Class level, Cover will delete an existing getter test. [Ref: TG-20611]

Important Notices

Test Review Plugin: Enabled by Default (from 2025.03.01)

Starting with the next release, the Test Review feature in the IntelliJ Plugin will be enabled by default.

• Tests must be accepted manually before appearing in your codebase.

• You can edit or reject tests as needed.

• If you haven’t tried it yet, enable it now from the IntelliJ Plugin's Diffblue Settings menu.

Read the Test Review documentation.

CLI: Deprecation of Build System Customization Options

As of this release, the following CLI options have been deprecated:

• --build-system-configuration

• --ignore-stylechecks

• --jacoco-command-diffblue

• --jacoco-command-manual

• --jacoco-xml-test-report

• --preflight-test-command

• --preflight-test-timeout

• --validation-timeout

• --validation-command

Migrating to a DiffblueBuild.yaml file is recommended for build system integration. See the configuration guide for more details.

Enhancements

• CLI: Cover now includes an --exclude-trivial-methods flag for CLI users to opt-out of testing trivial methods like getters and setters. This provides more control over test generation, helping avoid unnecessary tests for simple methods. [Ref: TG-22709]

• CLI: Build system customization options (e.g., --build-system-configuration) are now deprecated. Configure Cover using a DiffblueBuild.yaml file for improved build system integration. [Ref: TG-22640]

• CLI: Cover now supports projects which use Ant build systems. [Ref: TG-22631]

• CLI: Diffblue now offers Ant build system tasks via our public Maven repository, simplifying integration for Ant projects by enabling the use of a Maven dependency instead of specifying an absolute JAR file path. [Ref: TG-22611]

• CLI: Cover's environment and test creation summaries in log files now include the project module name, improving clarity and searchability. [Ref: TG-22581]

• Cover now generates @MethodsUnderTests annotations more concisely using available imports, enhancing test code readability and simplifying maintainability. [Ref: TG-22558]

• Reports: Enterprise users can now integrate their existing SSO providers, such as Keycloak, for secure authentication and role-based access control. This enhances data security, streamlines user management, and ensures compliance with enterprise policies. [Ref: TG-22509]

• Cover now more accurately identifies essential mock dependencies in Spring applications, resulting in tests with reduced unused mocking and improved readability. [Ref: TG-22411]

• Cover now generates better tests for Spring Controllers. Cover considers @ControllerAdvice classes when writing tests, leading to more complete and accurate results for applications using Spring's exception handling. [Ref: TG-20569]

Resolved Issues

• Resolved an issue which caused Cover to incorrectly parse compilation failures on Gradle projects when using Java 17.0.14+ and newer versions. [Ref: TG-22677]

• Resolved an issue where Cover did not automatically apply Spotless, when available, for test code formatting in Gradle builds. [Ref: TG-22658]

• Resolved an issue where Cover failed to run on certain multi-module Gradle projects due to module path errors. This caused Failed to run a simple example test (E011) warnings during execution. [Ref: TG-22592]

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]

Important Notices

CLI: Deprecation of Legacy Cover Reports Authentication Parameters

As of the 2025.03.02 release, the following authentication options have been marked as deprecated:

• reports.requiredusername

• reports.requiredpassword

Migrating to the new authentication parameters is required to avoid disruption to reporting pipelines. Use reports.users.upload.username and reports.users.upload.password instead.

Enhancements

• Reports: Cover Reports now uses reports.users.upload.username & reports.users.upload.password for upload authentication. Existing reports.requiredusername & reports.requiredpassword will be removed in a future release. [Ref: TG-22917]

• CLI: Cover now logs details when @InTestsMock and similar mocking advice is applied or cannot be applied. Logs include reasons such as missing frameworks or incompatible class types. [Ref: TG-22846]

• CLI: Cover’s test generation process now includes tests created without dependency injection. These tests are added only when they demonstrably increase code coverage compared to dependency injection-based tests. [Ref: TG-22842]

• Plugin: Diffblue Cover now includes an 'Activate License' option in the Status Bar widget and on the 'Diffblue Cover License' details screen. This provides easier access to change license keys. [Ref: TG-22841]

• Cover now supports Mockito 5.16.0. [Ref: TG-22836]

• Plugin: Diffblue Cover now features a redesigned tool panel for the test preparation phase. The updated interface provides clearer insights into preparation steps, including error detection and licensing checks. [Ref: TG-22776]

• Reports: Cover Reports now features a REST API for accessing coverage data. System administrators can leverage this API to integrate Reports with existing tools. [Ref: TG-22699]

• CLI: Cover now removes MaintainedByDiffblue tests failing validation. Previously, only tests in DiffblueTest classes could be removed during validation. Now failing tagged tests in classes that match the --class-name-template will also be removed. [Ref: TG-22604]

• Cover now supports writing tests for code which uses the Jersey RESTful Web Services library. [Ref: TG-22322]

• CLI & Plugin: Cover now prioritizes constructor usage over setters when generating tests. This results in more natural and representative test code. [Ref: TG-18736]

Resolved Issues

• Resolved an issue which, in some circumstances, caused Cover to write tests with when() Mockito stubs which were never used. [Ref: TG-22852]

• Resolved an issue which, in some circumstances, caused Cover to report Cover Annotations as 'Not Detected' during environment checks. [Ref: TG-22840]

• Reports: Resolved an issue which, in some circumstances, could have caused an inconsistent Diffblue test count due to unexpected surefire report files. [Ref: TG-22740]

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]

• When using Gradle, Junit 5 tests produced with the @DisplayName annotation may cause all the Diffblue tests to be removed from the class in validation [Ref: TG-22784]

• 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]

Enhancements

• Cover now supports Junit Jupiter 5.11.2 [Ref: TG-22109]

• CLI: Cover now outputs the default Maven or Gradle configuration to DiffblueBuild.yaml by running dcover build-default-config --maven or dcover build-default-config --gradle. [Ref: TG-22095]

• Cover: Improved String and char input descriptions for test method names and Javadoc. [Ref: TG-22083]

• Cover CLI & Plugin: Descriptive Test Naming is now enabled by default. Descriptive Test Naming can be disabled via the plugin settings or by using the --no-descriptive-test-names CLI option. [Ref: TG-22014]

• Improved Cover's ability to obtain objects using builders, specifically feign.Response objects with feign.Response.Builder, leading to better test coverage. [Ref: TG-22010]

• Cover now selects the most relevant assertions by comparing all tests written for a method under test. [Ref: TG-21627]

• Cover now avoids writing tests which pass null values into @Nonnull annotated method parameters. [Ref: TG-21387]

• Plugin: Cover's test creation settings can now be reset to default via the 'Restore Defaults' button in the plugin settings panel. [Ref: TG-20577]

Resolved Issues

• Resolved an issue which caused Cover to report DETECTED_LIBRARY_VERSIONS: SemverException: Invalid version, during environment checks, also causing subsequent environment checks to fail. [Ref: TG-22140]

• Reports: Resolved an issue which caused Cover to show empty coverage bars for multi-module projects in the project table. [Ref: TG-22072]

• Resolved an issue which caused Cover to inconsistently identify tests targeting the same method(s). Cover now has improved grouping of related tests. [Ref: TG-21989]

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]

• Cover may encounter an F009: Internal error while writing tests using Mockito 5. To avoid this issue use an earlier version of Mockito. [Ref: TG-19610]

• 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]

Improved Test Quality & Strength

• Stronger SQL Tests: Cover now writes stronger tests for code that uses java.sql.ResultSet by creating assertions on column values. It also prioritizes user-defined factories annotated with @InterestingTestFactory to increase test coverage.

• Builder Pattern Support: An issue has been resolved that prevented Cover from writing tests for classes using the builder pattern. Tests for these classes are now generated successfully, including assertions on the state set by setters.

• Enhanced Test Readability: To produce cleaner and more maintainable tests, Cover now avoids unnecessarily mocking objects, such as entities, when it can create an instance directly.

Configuration & Integration

• New Test Filters: To resolve an issue that could cause the Maven Spotless plugin to fail, DiffblueBuild.yaml v2.2 introduces new test filters for file and class matching (DIFFBLUE_TEST_*_PATTERN), which support both glob and regex formats. Existing REGEX filters remain supported for backward compatibility. For more details, see our documentation.

Important Notices

Upcoming Improvement to Test Readability

In an upcoming release, Cover will improve which methods are inlined, in particular in fluent-style method call chains such as builders. While this produces higher quality tests, please be aware that existing tests for affected classes will change, leading to noticeable changes in your test suite upon update.

Deprecation of Inlining Options

The inlining options (CLI: --act-into-assert, --arrange-into-act-assert, --inline-constants , --inline-constructors; Plugin: 'Test Style' dropdown and checkboxes 2-6 in the ‘Test Formatting’ panel) are now deprecated and will not have any effect on the code output. They will be removed in an upcoming Cover release. Please ensure these options are not used in any automated scripts.

Upcoming Breaking Change in DiffblueBuild.yaml

This only applies to projects that have a DiffblueBuild.yaml file. To speed up Diffblue Cover CLI, a new phase will be introduced in DiffblueBuild.yaml in an upcoming release. Instructions will be provided on how to update your DiffblueBuild.yaml file before updating the CLI (e.g. in CI/CD).

Enhancements

• Diffblue Cover now writes stronger tests for code using java.sql.ResultSet by creating assertions on column values. It also prioritizes user-defined factories annotated with @InterestingTestFactory, increasing test coverage and custom mocking capabilities. [Ref: TG-23665]

• Diffblue Cover now mocks Spring's ApplicationContext when it falls back to creating non-Spring tests in a Spring environment. This change avoids instantiating a full ApplicationContext, which could previously cause performance issues during test creation. [Ref: TG-23628]

• Diffblue Cover now detects and handles Spring-derived custom annotations, i.e. the annotation is in turn annotated with its corresponding Spring annotation. A new environment variable, DIFFBLUE_AUTOWIRED_ALTERNATIVE, allows for selecting the custom annotation to be used in the test output. If not specified, Diffblue Cover continues to use @Autowired in the generated tests. [Ref: TG-23328]

Resolved Issues

• Resolved an issue where Diffblue Cover would encounter an internal error and fail to write tests for methods with certain complex conditions. Test generation for this code is now unblocked. [Ref: TG-23667]

• Resolved an issue that prevented Diffblue Cover from writing tests for classes using the builder pattern, particularly when assertions were needed on the state set by setters. Tests for these builder classes are now generated successfully. [Ref: TG-23565]

• Resolved a Windows-specific issue where Diffblue Cover was unable to generate tests for some methods, resulting in an F009 internal error. This prevents failures that produced the message "An operation was attempted on something that is not a socket". [Ref: TG-23550]

• Resolved an issue that could cause the Maven Spotless plugin to fail. DiffblueBuild.yaml v2.2 introduces new test filters for file and class matching (DIFFBLUE_TEST_*_PATTERN), supporting both glob and regex formats. Existing REGEX filters are still supported for backward compatibility. [Ref: TG-23390]

• Resolved an issue where Diffblue Cover would generate tests with unnecessary mocks for instantiable objects. Tests for code using patterns like entity objects are now more readable and contain fewer mock setups. [Ref: TG-21664]

Known Issues

• Plugin: Diffblue Cover incorrectly displays a menu option to write tests for existing test files. [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]

• Cover may encounter an F009 (Internal error) caused by a ClassCircularityError involving org/mockito/configuration/MockitoConfiguration when writing tests with Mockito 5. To avoid this, use an earlier version of Mockito. Downgrading to Mockito 4.x is the recommended workaround. [Ref: TG-19610]

• 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]

• Diffblue Cover does not currently support test creation for projects using Java 24; please use JDK 21 or lower. [Ref: TG-22920]

LLM String Generation for Test Inputs (Beta)

• Selective Control: Introduces the @InTestsUseLLM annotation, enabling selective use of LLM-generated string inputs for specific methods, classes, or packages. This allows users to balance test generation speed and API costs by applying realistic string generation only where most needed. Requires cover-annotations library v1.8.0+ and an active LLM Configuration (Beta). For more information, see the LLM Input Annotations documentation.

• Anthropic Models: Resolved an issue that prevented using Anthropic models with the LLM String Generation for Test Inputs beta feature.

CLI Enhancements & Stability

• dcover fix-build Reliability: Resolved an issue where the dcover fix-build command could unreliably update pom.xml files. The command now modifies Maven project configurations with improved reliability.

• dcover validate Command: Resolved an issue where the dcover validate command could remove valid fields, imports, or entire test classes. The command now correctly identifies and removes only individual failing tests.

Test Generation & Quality

• Google Protobuf Support: Resolved a security sandbox policy violation that prevented Cover from writing tests for code using Google Protobuf. Test generation now proceeds successfully in this scenario.

• JUnit Annotation Compatibility: Resolved an issue that could cause Cover to generate tests with incompatible @RunWith and @ExtendWith annotations, ensuring all generated tests have a valid configuration.

IntelliJ Plugin

• Plugin Stability: Resolved a rare issue that could cause an 'Internal Error' after Environment Detection, preventing some users from writing tests. Users in affected environments can now successfully write tests.

Important Notices

Upcoming End of Support for IntelliJ 2025.1

This release is the final release that supports IntelliJ 2025.1. In line with our policy of supporting the two most recent major versions, support for 2025.1 will be discontinued in an upcoming release.

To continue receiving Diffblue Cover updates and support, users on IntelliJ 2025.1 are advised to upgrade to IntelliJ 2025.2 or newer.

Enhancements

• Diffblue Cover now generates more effective tests for Spring MVC controller methods that use HttpRequest and HttpSession parameters, improving test coverage for web controllers. [Ref: TG-23940]

• Diffblue Cover now writes tests more quickly for projects containing Spring entities with a large number of fields, resulting in improved overall performance during test generation. [Ref: TG-23839]

• Diffblue Cover now supports the @InTestsUseLLM annotation, enabling selective use of LLM-generated string inputs for specific methods, classes, or packages. This allows users to balance test generation speed and API costs by applying realistic string generation only where most needed. This feature requires cover-annotations library v1.8.0+ and an active LLM Configuration (Beta). [Ref: TG-23811]

Resolved Issues

• Resolved an issue where a security sandbox policy violation would prevent Diffblue Cover from writing tests for code using Google Protobuf. Test generation will now proceed for methods that previously triggered an R011 output code in this scenario. [Ref: TG-23902]

• Resolved an issue which prevented the use of Anthropic / Claude models for the LLM String Generation for Test Inputs beta feature. Diffblue Cover can now correctly connect to this provider to generate realistic string values in tests. [Ref: TG-23892]

• Plugin: Resolved a rare issue that caused an 'Internal Error' after Environment Detection due to a class path resolution problem, which prevented some users from writing tests. [Ref: TG-23890]

• CLI: Resolved an issue that caused the dcover fix-build command to unreliably update pom.xml files. The command now reliably modifies Maven project configurations to resolve testability blockers. [Ref: TG-23392]

• Resolved an issue that could cause Diffblue Cover to generate tests with incompatible @RunWith and @ExtendWith annotations. All generated tests now have compatible annotation configurations. [Ref: TG-23378]

• Resolved an issue where the dcover validate command could incorrectly remove valid fields, imports, or entire test classes. The command now correctly identifies and removes only individual failing tests. [Ref: TG-23151]

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]