monorepo

packages/helpers/deferred.test.ts

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+import test from "ava"
+import { createDeferred } from "./deferred.js"
+
+test("resolve", async (t) => {
+  const deferred = createDeferred<string>()
+  setTimeout(() => deferred.resolve("hi"))
+  t.is(await deferred, "hi")
+})
+
+test("reject", async (t) => {
+  const deferred = createDeferred()
+  setTimeout(() => deferred.reject(new Error("oops")))
+  await t.throwsAsync(() => deferred, { instanceOf: Error, message: "oops" })
+})

packages/helpers/deferred.ts

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+// eslint-disable-next-line import/no-unused-modules
+export type Deferred<T> = PromiseLike<T> & {
+  resolve: (value: T | PromiseLike<T>) => void
+  reject: (reason?: unknown) => void
+}
+
+export function createDeferred<T = void>(): Deferred<T> {
+  let resolve: (value: T | PromiseLike<T>) => void
+  let reject: (reason?: unknown) => void
+
+  const promise = new Promise<T>((_resolve, _reject) => {
+    resolve = _resolve
+    reject = _reject
+  })
+
+  return {
+    then: promise.then.bind(promise),
+    resolve: (value) => resolve(value),
+    reject: (reason) => reject(reason),
+  }
+}

packages/helpers/package.json

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+{
+  "name": "reacord-helpers",
+  "private": true,
+  "devDependencies": {
+    "@types/node": "^16.11.14"
+  }
+}

packages/helpers/raise.ts

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+import { toError } from "./to-error.js"
+
+export function raise(error: unknown): never {
+  throw toError(error)
+}

packages/helpers/reject-after.ts

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+import { setTimeout } from "node:timers/promises"
+import { toError } from "./to-error.js"
+
+export async function rejectAfter(
+  timeMs: number,
+  error: unknown = `rejected after ${timeMs}ms`,
+): Promise<never> {
+  await setTimeout(timeMs)
+  return Promise.reject(toError(error))
+}

packages/helpers/to-error.ts

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+export function toError(value: unknown) {
+  return value instanceof Error ? value : new Error(String(value))
+}

packages/helpers/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json"
+}

packages/helpers/types.ts

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+export type MaybePromise<T> = T | Promise<T>

packages/helpers/wait-for-with-timeout.ts

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+import { rejectAfter } from "./reject-after.js"
+import type { MaybePromise } from "./types.js"
+import { waitFor } from "./wait-for.js"
+
+export function waitForWithTimeout(
+  condition: () => MaybePromise<boolean>,
+  timeout = 1000,
+  errorMessage = `timed out after ${timeout}ms`,
+) {
+  return Promise.race([waitFor(condition), rejectAfter(timeout, errorMessage)])
+}

packages/helpers/wait-for.ts

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+import { setTimeout } from "node:timers/promises"
+import type { MaybePromise } from "./types.js"
+
+export async function waitFor(condition: () => MaybePromise<boolean>) {
+  while (!(await condition())) {
+    await setTimeout(100)
+  }
+}