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About BeyondTesting.dev

BeyondTesting.dev explores how software can be correct by design, not just through testing.

It focuses on Design by Contract (DbC), a methodology that embeds correctness into code through preconditions, postconditions, and invariants.

This isn't a testing library. It's a mindset shift.

Why this site exists​

Most developers spend their careers chasing correctness with tests. Writing them. Updating them. Rewriting them.

We're not here to chase correctness. We're here to design it in from the start.

BeyondTesting.dev stands for correctness, clarity, and a refusal to settle.

BeyondTesting.dev shows how contracts can do just that — through clear diagrams, real code examples, and language-native support.

Design by Contract originated in Bertrand Meyer's book Object-Oriented Software Construction (1992).
It formalized preconditions, postconditions, and invariants — not as documentation, but as executable guarantees.
The Eiffel programming language was the first to enforce these principles by design.

Read the full book - 1284 pages, (PDF)

Who it's for​

  • Curious developers who would prefer baking in acceptance criteria in the code rather than the tests
  • Developers working on code that can't afford to fail
  • Anyone who wants their code to speak for itself

Who's behind it​

Built and maintained by Andrea Mancuso.
Connect on LinkedIn.

Want to contribute?​

The project is open source — if you've got ideas, examples, or time to spare, you're more than welcome.

The source code is available on GitHub.

Feel free to help us translate the content to other languages, suggest new diagrams, etc.

Every contribution counts.