# For agents: Testing uses the same language

OpenProse today · board 9 of 17 · 2026-10-09.
This deck records dated experimental evidence, not general reliability.

Compose controlled tests from fixture, observation, and evaluator contracts, retaining every outcome.

## On the slide

**Tests, fixtures, observations, and evaluators can all be contracts.**

Exercise a case.

Collect evidence.

Check the expected property.

Retain failures and incomplete attempts.

## Explanation

Testing is now a published standard-library contract. A caller selects the cases, subject contracts, inputs, expectations, and finite attempt bounds. It can also supply contracts for establishing a fixture world, collecting observations, and evaluating results. Negative cases can pass by exposing expected violations. Valid alternatives should remain acceptable. A mock must identify what it implements and what it cannot establish; a written promise of a tool is not a working tool. These distinctions separate defective work, inadequate checking, missing evidence, and failed test execution. Authored tests alone are not execution results.

This is the experiment's structure: arrange the case, exercise it, collect evidence, and compare the findings with the expected property. The next slide proposes reusable checking contracts that a test could supply as evaluators. Those same checkers could assess ordinary executions outside a test. The distinction is the controlled case and its expectations, not a separate language or an entirely different evaluator.

## Whiteboard sequence

Open only the frames useful to the question. Later frames add to the same board;
the final frame contains the complete drawing.

- [Frame 1 — black core](https://prose.md/visual-guide/2026-10-09/current/slide-09-layer-01.png)
- [Frame 2 — cumulative reveal](https://prose.md/visual-guide/2026-10-09/current/slide-09-layer-02.png)
- [Frame 3 — cumulative reveal](https://prose.md/visual-guide/2026-10-09/current/slide-09-layer-03.png)
- [Frame 4 — final](https://prose.md/visual-guide/2026-10-09/current/slide-09-layer-04.png)

These explanations add no normative requirements. Read the
[selected kernel 0.3.0-rc.3](https://pkg.prose.md/releases/0.3.0-rc.3/core/README.md) for language rules.

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