feat: provide input option

closes #720

src/core.ts

@@ -48,8 +48,9 @@ const processCwd = Symbol('processCwd')
 export interface Options {
   [processCwd]: string
   cwd?: string
-  verbose: boolean
   ac?: AbortController
+  input?: string | Buffer | Readable | ProcessOutput | ProcessPromise
+  verbose: boolean
   env: NodeJS.ProcessEnv
   shell: string | boolean
   nothrow: boolean
@@ -187,18 +188,23 @@ export class ProcessPromise extends Promise<ProcessOutput> {
   }
 
   run(): ProcessPromise {
-    const $ = this._snapshot
-    const self = this
     if (this.child) return this // The _run() can be called from a few places.
     this._prerun() // In case $1.pipe($2), the $2 returned, and on $2._run() invoke $1._run().
 
+    const $ = this._snapshot
+    const self = this
+    const input = ($.input as ProcessPromise | ProcessOutput)?.stdout ?? $.input
+
+    if (input) this.stdio('pipe')
+
     $.log({
       kind: 'cmd',
       cmd: this._command,
       verbose: self.isVerbose(),
     })
 
     this.zurk = exec({
+      input,
       cmd: $.prefix + this._command,
       cwd: $.cwd ?? $[processCwd],
       ac: $.ac,

test/core.test.js

@@ -15,7 +15,7 @@
 import assert from 'node:assert'
 import { test, describe, beforeEach } from 'node:test'
 import { inspect } from 'node:util'
-import { Writable } from 'node:stream'
+import { Readable, Writable } from 'node:stream'
 import { Socket } from 'node:net'
 import { ProcessPromise, ProcessOutput } from '../build/index.js'
 import '../build/globals.js'
@@ -106,6 +106,20 @@ describe('core', () => {
     }
   })
 
+  test('handles `input` option', async () => {
+    const p1 = $({ input: 'foo' })`cat`
+    const p2 = $({ input: Readable.from('bar') })`cat`
+    const p3 = $({ input: Buffer.from('baz') })`cat`
+    const p4 = $({ input: p3 })`cat`
+    const p5 = $({ input: await p3 })`cat`
+
+    assert.equal((await p1).stdout, 'foo')
+    assert.equal((await p2).stdout, 'bar')
+    assert.equal((await p3).stdout, 'baz')
+    assert.equal((await p4).stdout, 'baz')
+    assert.equal((await p5).stdout, 'baz')
+  })
+
   test('pipes are working', async () => {
     let { stdout } = await $`echo "hello"`
       .pipe($`awk '{print $1" world"}'`)