Diffblue Cover
Diffblue Cover generates unit tests for Java and Kotlin projects, with tools for test coverage, code changes, and refactoring.
What Diffblue Cover is
Diffblue Cover generates unit tests for Java and Kotlin projects, with tools for test coverage, code changes, and refactoring. It is available as an IntelliJ plugin, command-line tool, and CI pipeline integration. Supported pipeline environments include GitHub, GitLab, Maven, Jenkins, Azure, and AWS. The maker says generated tests compile, run, and validate the code’s current behavior. Cover Reports visualizes coverage, coverage risk, testability, and code complexity. Cover Optimize selects tests to validate code changes; Cover Refactor can suggest and apply Java refactorings intended to improve observability and testability.
Cover runs locally in the customer environment, and the maker says no data leaves the organization. Projects need Java 8, 11, 17, or 21, or Kotlin, plus Maven 3.2.5+ or Gradle 4.9+; they must compile and have no failing unit tests. JUnit and TestNG are supported. The Community Edition costs nothing, and a free trial is listed for no cost, billed 14 days. Each use requires a remote licensing-server check; offline activation is available only for Enterprise through the CLI.
Good
- Runs locally without sending data outside the organization.
- Available as an IntelliJ plugin, CLI, and CI integration.
- Supports JUnit and TestNG.
- Community Edition costs nothing.
Watch out
- Projects must compile and have no failing unit tests.
- Each use requires a remote licensing-server check.
- Offline activation is limited to Enterprise through the CLI.
Who it suits
Cover suits teams working on Java or Kotlin projects that want unit test generation within an IDE, command-line, or CI workflow. It may also suit organizations that need local execution and tools for coverage, test selection, or refactoring.
Verdict
Diffblue Cover combines Java and Kotlin unit test generation with reporting, change-focused test selection, and refactoring tools. Check its project prerequisites and remote licensing check against your environment before choosing it.
Plans and prices
From Diffblue Cover's own pricing page, checked 7 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Community Edition | Free | IntelliJ plugin · perpetual license after product verification |
| Free trial | Free | Diffblue Cover trial · trial length stated on GitHub and GitLab pages · 14 days |
| Enterprise Edition | Priced on request | Paid license · offline activation available through CLI |
| Teams Edition | Priced on request | Paid license · price not stated on opened pages |
The facts
Each one read from Diffblue Cover's own pages, with the date it was checked.
What it does
- CI integrations
- The maker lists GitHub, GitLab, Maven, Jenkins, Azure, and AWS among supported pipeline environments.checked 7 Oct 2026
- Data handling
- The maker says Cover runs locally in the customer environment without requiring a cloud service and that no data leaves the organization.checked 7 Oct 2026
- License connectivity
- Cover requires a remote check with Diffblue’s licensing server each time it is used; offline activation is available only for Enterprise Edition through the CLI.checked 7 Oct 2026
- Optimization
- Cover Optimize selects the unit tests needed to validate code changes and is integrated into Cover CLI and Cover Pipeline.checked 7 Oct 2026
- Project prerequisites
- The getting-started page lists Java 8, 11, 17, or 21 compatible source or Kotlin, Maven 3.2.5+ or Gradle 4.9+, and a project that compiles and has no failing unit tests.checked 7 Oct 2026
- Purpose
- Diffblue Cover automatically writes human-like Java unit tests for Java and Kotlin projects.checked 7 Oct 2026
- Refactoring
- Cover Refactor can suggest and apply Java code refactorings intended to improve observability and testability.checked 7 Oct 2026
- Reports
- Cover Reports visualizes test coverage, coverage risk, testability, and code complexity.checked 7 Oct 2026
- Support
- Community support is provided through the Community forum, while more comprehensive support is included with Teams and Enterprise editions.checked 7 Oct 2026
- Test frameworks
- The plugin getting-started page states that JUnit and TestNG are supported.checked 7 Oct 2026
- Test quality
- The maker says generated tests compile, run, and validate the current behavior of the code.checked 7 Oct 2026
- Workflows
- Cover is offered as an IntelliJ plugin, a command-line tool, and a CI pipeline integration.checked 7 Oct 2026
The company
- Company
- Diffblue was founded in 2016 as a spin-out of the University of Oxford and is headquartered in Oxford.checked 7 Oct 2026
- Founded
- 2016checked 28 Sep 2026
- Headquarters
- Oxford, United Kingdomchecked 28 Sep 2026
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