Microsoft Releases Open-Source AI Agent for Automated Unit Test Generation

Microsoft released code-testing-generator on July 31, 2026, an open-source AI agent designed to automate unit test generation across any programming language. Operating via a research-plan-implement (RPI) pipeline, the agent analyzes repositories, plans and writes tests, and validates them by checking assertions and running test suites. The agent is available via the dotnet-test plugin on GitHub, supporting GitHub Copilot CLI and Visual Studio Code in preview.

Code-testing-generator agent release

• ▪The code-testing-generator agent currently supports only unit tests, while integration, end-to-end, browser, and performance tests remain outside its scope
• ▪The dotnet-test plugin works with GitHub Copilot CLI and is available in Visual Studio Code and VS Code Insiders as a preview feature
• ▪The code-testing-generator agent is available through the dotnet-test plugin in the dotnet/skills repository on GitHub
• ▪Microsoft released code-testing-generator, an open-source AI agent that generates unit tests in any programming language, on July 31, 2026
• ▪The code-testing-generator agent learns from a user's software repository to plan, write, and verify unit tests before completion

Research-plan-implement pipeline architecture

• ▪During planning, the code-testing-generator agent maps behaviors to test files, starting with simple code before progressing to code with more dependencies
• ▪The code-testing-generator agent coordinates test generation using a research-plan-implement pipeline that analyzes the repository to identify languages, frameworks, existing tests, and build commands
• ▪Based on workload, the code-testing-generator agent selects from three execution paths: Direct, Single pass (or One-pass), and Iterative

Test validation quality checks

• ▪The code-testing-generator agent validates tests by checking for weak or missing assertions, ensuring requested scenarios are covered, and testing if small code changes cause failures
• ▪The code-testing-generator agent's validation process includes building the workspace, running the test suite, and confirming the repository's test command detects the new tests