matchers

matchers holds one Jest matcher, toSatisfies. It is on the main entry and on its own entry:

import { matchers } from '@repobuddy/jest'
import { toSatisfies } from '@repobuddy/jest/matchers'

Importing either entry does not register the matcher. Pass it to expect.extend().

toSatisfies

Passes when the received value satisfies an expectation, checked by satisfier.

function toSatisfies(this: any, actual: unknown, expectation: Expectation): {
  pass: boolean
  message: () => string
}

In a test you call it as expect(actual).toSatisfies(expectation).

Parameter	Type	Default	Effect
expectation	Expectation from satisfier	required	The value, regular expression, or predicate to check actual against. A property in an object expectation can be a predicate.

Returns a Jest matcher result. On failure, the message lists each property that did not satisfy its expectation. On a failing .not, the message prints the received value.

Register it

import { expect } from '@jest/globals'
import { toSatisfies } from '@repobuddy/jest/matchers'

expect.extend({ toSatisfies })

To register it for every test file, put those lines in a file listed in setupFilesAfterEnv.

Types

The package declares toSatisfies on jest.Matchers (for @types/jest globals) and on the Matchers interface of @jest/expect (for expect from @jest/globals). Importing from @repobuddy/jest/matchers brings the declarations in.

Examples

From the spec:

expect({ a: 1 }).toSatisfies({ a: (x) => x === 1 })

A failing check:

expect({ a: 1 }).toSatisfies({ a: (x) => x === 2 })
// expect(received).toSatisfies()
//
// expect 'a' to satisfy x => x === 2, but received 1

A failing .not:

expect({ a: 1 }).not.toSatisfies({ a: (x) => x === 1 })
// expect(received).not.toSatisfies()
//
// received {"a": 1}

The ts-esm, ts-cjs, js-esm, and dual-ts-* fixtures in this repository run the same checks through @repobuddy/jest/matchers.

Related

• API index