fix: settle the promise when the input stream ends

src/read.ts

@@ -90,7 +90,10 @@ export async function read<T extends string | number = string> ({
     }
     /* c8 ignore stop */
 
+    let finished = false
+
     const done = () => {
+      finished = true
       rl.close()
       clearTimeout(timer)
       m.mute()
@@ -121,6 +124,19 @@ export async function read<T extends string | number = string> ({
       /* c8 ignore stop */
     })
 
+    // readline emits 'close' without ever emitting 'line' when the input stream
+    // ends first, which is what happens any time stdin is not something a user
+    // can type into: /dev/null, an already closed pipe, a child process spawned
+    // without stdin. Settle the promise here or it never settles at all, and the
+    // caller waits on it until the event loop empties and the process exits with
+    // no error to report. Treated as a cancel, same as SIGINT, since both mean no
+    // answer is coming.
+    rl.on('close', () => {
+      if (!finished) {
+        onError(new Error('canceled'))
+      }
+    })
+
     // TODO: add tests for sigint
     /* c8 ignore start */
     rl.on('SIGINT', () => {

test/basic.ts

@@ -1,5 +1,6 @@
 import { test } from 'node:test'
 import { strict as assert } from 'node:assert'
+import { PassThrough } from 'node:stream'
 import { read } from '../src/read.ts'
 import spawnRead from './fixtures/setup.ts'
 
@@ -73,6 +74,25 @@ const main = () => {
     // @ts-expect-error
     await assert.rejects(() => read({ default: {} }))
   })
+
+  test('input stream ends without a line', async () => {
+    const input = new PassThrough()
+    const output = new PassThrough()
+    input.end()
+
+    await assert.rejects(
+      () => read({ prompt: 'Username:', input, output }),
+      /canceled/
+    )
+  })
+
+  test('input stream ends after a line still resolves', async () => {
+    const input = new PassThrough()
+    const output = new PassThrough()
+    input.end('a user\n')
+
+    assert.equal(await read({ prompt: 'Username:', input, output }), 'a user')
+  })
 }
 
 if (process.argv[2] === 'child') {