Function causesArb

test/utils/cause.ts:5–49

(
  n: number,
  error: fc.Arbitrary<E>,
  defect: fc.Arbitrary<unknown>
)

import * as fc from "fast-check"

export const causesArb = <E>(
  n: number,
  error: fc.Arbitrary<E>,
  defect: fc.Arbitrary<unknown>
): fc.Arbitrary<Cause.Cause<E>> => {
  const fiberId: fc.Arbitrary<FiberId.FiberId> = fc.tuple(
    fc.integer(),
    fc.integer()
  ).map(([a, b]) => FiberId.make(a, b))

  const empty = fc.constant(Cause.empty)
  const failure = error.map(Cause.fail)
  const die = defect.map(Cause.die)
  const interrupt = fiberId.map(Cause.interrupt)

  const annotated = (n: number): fc.Arbitrary<Cause.Cause<E>> => {
    return fc.tuple(causesN(n - 1), fc.anything()).map(
      ([cause, annotation]) => Cause.annotated(cause, annotation)
    )
  }

  const sequential = (n: number): fc.Arbitrary<Cause.Cause<E>> => {
    return fc.integer({ min: 1, max: n - 1 }).chain((i) =>
      causesN(i).chain((left) => causesN(n - i).map((right) => Cause.sequential(left, right)))
    )
  }

  const parallel = (n: number): fc.Arbitrary<Cause.Cause<E>> => {
    return fc.integer({ min: 1, max: n - 1 }).chain((i) =>
      causesN(i).chain((left) => causesN(n - i).map((right) => Cause.parallel(left, right)))
    )
  }

  const causesN = (n: number): fc.Arbitrary<Cause.Cause<E>> => {
    if (n === 1) {
      return fc.oneof(empty, failure, die, interrupt)
    }
    if (n === 2) {
      return annotated(n)
    }
    return fc.oneof(annotated(n), sequential(n), parallel(n))
  }

  return causesN(n)
}

export const causes: fc.Arbitrary<Cause.Cause<string>> = causesArb(
  1,