`arbitrary`

fast-check utilities and arbitraries for effect-ts datatypes.

Importing
Modules
1. monad
2. data
3. time
4. function
5. effect

Importing

Every type and function below can be imported directly from effect-ts-laws/arbitrary.

Example

Importing arbitraries from this package:

import {Option as OP, pipe} from 'effect'
import {tinyArray, tinyInteger, option} from 'effect-ts-laws/arbitrary'
import fc from 'fast-check'

const arbitrary: fc.Arbitrary<OP.Option<number>[]> = pipe(
  tinyInteger,
  option,
  tinyArray
)

Modules

monad

Monad instance for the fast-check Arbitrary type, and a type lambda for the type.

There is also an Equivalence instance which will try to find counter-examples to the equivalence and return true if none found.

Example

Using the flatMap function:

import {Effect as EF, flow, pipe} from 'effect'
import {Monad} from 'effect-ts-laws/arbitrary'
import fc from 'fast-check'

const greaterThanOne = (i: number): EF.Effect<string, Error> =>
  i > 1 ? EF.succeed('OK') : EF.fail(new Error('KO'))

const oneThirdFail: fc.Arbitrary<EF.Effect<string, Error>> = pipe(
  fc.integer({min: 1, max: 3}),
  Monad.flatMap(flow(greaterThanOne, fc.constant)),
)