feat: add optional delay for retry (#335)

* feat: add optional delay for `retry`

* chore: simplify retry type decl

README.md

@@ -312,7 +312,7 @@ $.shell = '/usr/bin/bash'
 
 Or use a CLI argument: `--shell=/bin/bash`
 
-#### `$.spanw`
+#### `$.spawn`
 
 Specifies a `spawn` api. Defaults to `require('child_process').spawn`.
 
@@ -371,6 +371,9 @@ successful attempt, or will throw after specifies attempts count.
 import {retry} from 'zx/experimental'
 
 let {stdout} = await retry(5)`curl localhost`
+
+// with a specified delay between attempts
+let {stdout} = await retry(3, 500)`npm whoami`
 ```
 
 #### `echo()`

experimental.d.ts

@@ -23,7 +23,7 @@ export const echo: Echo
 interface Retry {
   (pieces: TemplateStringsArray, ...args: any[]): Promise<ProcessOutput>
 }
-export const retry: (count: number) => Retry
+export const retry: (count?: number, delay?: number) => Retry
 
 type StopSpinner = () => void
 export function startSpinner(title: string): StopSpinner

experimental.mjs

@@ -16,11 +16,12 @@ import {ProcessOutput} from './index.mjs'
 
 // Retries a command a few times. Will return after the first
 // successful attempt, or will throw after specifies attempts count.
-export const retry = (count = 5) => async (cmd, ...args) => {
+export const retry = (count = 5, delay = 0) => async (cmd, ...args) => {
   while (count --> 0) try {
     return await $(cmd, ...args)
   } catch (p) {
     if (count === 0) throw p
+    if (delay) await sleep(delay)
   }
 }
 

test.mjs

@@ -241,12 +241,14 @@ if (test('YAML works')) {
 
 if (test('Retry works')) {
   let exitCode = 0
+  let now = Date.now()
   try {
-    await retry(5)`exit 123`
+    await retry(5, 50)`exit 123`
   } catch (p) {
     exitCode = p.exitCode
   }
   assert.equal(exitCode, 123)
+  assert(Date.now() >= now + 50 * (5 - 1))
 }
 
 let version