Diffblue Cover - AI Agent for unit testing downloads statistics

Diffblue Cover

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The fastest, most reliable way to automatically generate quality unit tests

Diffblue Cover is an AI agent for automating the generation, maintenance and management of Java unit tests.

Unlike LLM-based coding assistants that help write individual tests when prompted, Diffblue Cover uses reinforcement learning (RL) to autonomously produce comprehensive coverage across entire codebases, perfect for meeting coverage gates, catching regressions, and shipping with confidence.

Proven at Enterprise Scale:

• US Aerospace and Defense company: 1M lines of code coverage initiative • Goldman Sachs: From 36% to 72% in less than 10% of the time it would take to do it manually • US Pension & Retirement System: 70% unit coverage without manual effort • Handles what others can't: Complex Spring contexts, Guice, legacy singletons, millions of lines of code without OOM errors, tests are guaranteed to compile and pass

Diffblue Cover augments developers by automating away tedious and time-consuming aspects of the Java unit test generation process.

Documents actual behavior: Unit tests reveal what your code really does (not what comments claim), essential for understanding legacy systems and inherited codebases.

Enables rapid coverage increases: Creates unit tests in bulk, covering all relevant branches to rapidly improve coverage and enable teams to reach and maintain coverage goals.

Handles enterprise complexity: Works with complex Spring contexts, Mockito configurations, and legacy patterns that cause other tools to fail with OOM errors.

Enables safe refactoring: Create regression safety net before Java version upgrades, cloud migrations, or modernization initiatives. Know what breaks before production.

Secures inherited codebases: Generate comprehensive test suites for acquired or legacy code with 0% coverage, creating a safety net for integration and modification.

Unblocks CI/CD pipelines: Rapidly increase coverage to meet gates blocking your deployments, achieving in days what would take months manually.

Use Cases:

Accelerate Development

✓ Sprint velocity improvement - Stop spending 30-50% of time writing tests

✓ New feature protection - Ensure all new code has regression tests

✓ Refactoring confidence - Safe changes with comprehensive test coverage

✓ Code review acceleration - PRs include tests automatically

Meet Requirements

✓ Coverage gates and requirements - Achieve targets faster than manual writing

✓ Compliance mandates - SOC2/ISO/MRM requiring test evidence

✓ Quality initiatives - Systematic improvement of test coverage

✓ Technical debt reduction - Address testing gaps efficiently

Enable Transformation

✓ Java version upgrades - Test safety net for 8→11/17/21/25 migrations

✓ Architecture modernization - Confidence to refactor and improve

✓ Cloud migration - Ensure functionality during platform changes

✓ M&A integration - Quickly understand and test acquired code

Plugin Capabilities:

IntelliJ Plugin Features

✓ Generate tests for methods, classes, or entire packages

✓ See coverage visualization in gutter icons

✓ One-click test generation from context menu

✓ Automatic test file creation and organization

✓ Works with your existing test framework

Community Edition: Start free with 25 tests per month - perfect for trying Diffblue on your codebase

Teams Edition: Unlimited test generation for teams serious about coverage

Enterprise CLI: For maximum automation and CI/CD integration, our CLI tool provides additional capabilities including batch processing and pipeline integration. Learn more about Diffblue CLI

Prerequisites:

✓ Java 8, 11, 17, 21 or 25 compatible source code

✓ Your project must be compiled with unit testing dependencies (we can add these automatically if needed)

✓ Maven 3.2.5+ or Gradle 4.9+ build tools

✓ Existing tests should pass before generating new ones

✓ JUnit and TestNG frameworks supported

For details, see Diffblue Cover Specifications & Requirements.

Works with your stack:

• Spring Boot 2.x, 3.x and 4.x • All major Java frameworks • Complex dependency injection • Mockito and other mocking frameworks • No code changes required to start

We’re here to help Check out the Diffblue Docs, or visit our Support page. Support levels are based on product plans. Please see our support page to learn about your support options.