matches
Checks whether output text matches a regular expression.
When to use
The output must follow a text pattern, such as an order ID format.
Why use it
A regular expression checks format without requiring one exact value.
Example
This example evaluates a fixed output so you can see what the metric checks. Replace target with your agent or function when building your own suite.
import { matches, runEvalSuite } from '@anvia/core/evals'
const result = await runEvalSuite({
name: 'matches-example',
cases: [
{
id: 'order-id-format',
input: 'Return the order ID only.',
},
],
target: async () => 'ORD-123456',
metrics: [
matches({ expected: /^ORD-\d{6}$/ }),
],
})
console.log(result.results[0]?.scores)Read the result
This example passes with score true. Order ID: ORD-123456 fails because the pattern requires the entire output to be the ID.
What it needs
Output text and an expected regular expression; passes when it matches anywhere in the text. Anchor the pattern to require a full-string match.
Keep in mind
Use ^ and $ to anchor a pattern to the beginning and end of the answer. Without anchors, a match anywhere in the answer is enough. The metric resets the regular expression’s lastIndex before and after checking.
For an object returned by your target, use actual to select the value to check, such as actual: ({ output }) => output.answer. Anvia automatically reads the output field of an agent response.
An invalid result means the metric could not make a valid judgment, for example because required input was missing or a model call failed. Inspect it separately from a failed check.