TDD (test-driven development) is a practice rather than a single product, so the answer is a test framework to write the tests in. pytest 1 is a framework for writing small, readable tests that scale to complex applications and libraries, and Robot Framework 3 and Cucumber 9 suit plain-language acceptance tests, while Playwright 2 and Selenium 4 cover browser-level end-to-end testing.

1. 1

   pytestpytest.orgverified and signed

   A Python testing framework for writing small, readable tests that scale to complex functional testing of applications and libraries 1.

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   +22 community tools built for it

   for agents: unittest · test

2. 2

   Robot Frameworkrobotframework.orgverified and signed

   An open source automation framework for test automation with human-readable keyword syntax, extensible in Python 3.

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   +4 community tools built for it

   for agents: testautomation · testing · acceptancetesting

3. 3

   Playwright Testplaywright.devwebsite read, tools not yet checked

   A full-featured test runner with auto-waiting, assertions and parallelism across Chromium, Firefox and WebKit 2.

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   official:SDK · playwright+232 community tools built for it

4. 4

   Cucumbercucumber.ioverified and signed

   A tool for running automated acceptance tests written in plain language that anyone on the team can read 9.

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   for agents: cucumber-messages · specflow · cucumber