# Testing and evals

> Code is tested, prompts are scored, and which to reach for.

| | Checks | Costs |
|---|---|---|
| A test | that a job's code does the thing | nothing: no model is asked |
| An eval | that a prompt led the model to decide well | a model call per case |

## Jobs are tested

A test sits beside its job, named `<job>.test.ts`, with cases from
`@chloejs/core/test`. Test the rules, which is the part that is code:

```ts
// The one rule in this job, checked without a database and without a model.
import { about, is } from "@chloejs/core/test";

import { stuck, GRACE_HOURS } from "./stuck-orders.ts";
import type { Order } from "../services/ordersService.ts";

about("which orders are worth chasing");

const now = Date.parse("2026-09-20T12:00:00Z");
const hours = (n: number) => new Date(now + n * 60 * 60 * 1000).toISOString();
const order = (extra: Partial<Order>): Order => ({
  id: "A-1", customer: "c-1", placed: hours(-200), paid: true, promised: hours(-48), total: 1000, lines: [], ...extra,
});

is("paid, unshipped and two days late is stuck", stuck(order({}), now), true);
is("the same order once it ships is not", stuck(order({ shipped: hours(-1) }), now), false);
is("an unpaid one is not ours to chase", stuck(order({ paid: false }), now), false);
is("one still inside the grace period is not yet late", stuck(order({ promised: hours(-GRACE_HOURS + 1) }), now), false);
is("and one due tomorrow is not late at all", stuck(order({ promised: hours(24) }), now), false);
```

`node agents/<id>/jobs/<job>.test.ts` runs one and prints each case. The more
of a job that moves from a model step into code, the more of it a test covers.

## Prompts are scored

```sh
npx chloe evals <agent>
```

An eval file in the agent's `evals/` folder is one job, with a case per
situation: what each tool answers, and what the agent should and should not have
done. Run it before and after you change a purpose or a skill, because words
are the easiest thing to make worse without noticing.

Nothing in a case runs for real. A tool the case does not answer is refused, so
an eval cannot send an email or ship an order. Add a tool to the agent and its
cases fail until they answer it.

A tool's answer matches only the exact arguments it lists. Mark one
`"anyArgs": true` when the arguments do not change it, and give `"times"` when
one answer covers several calls.