Output streams do not emit "end" event if execution fails

[anomiex]

Consider this code (using node 18.13.0 and execa 6.1.0)

import { execa } from 'execa';

const proc = execa( "does not exist", [], { stdio: [ 'ignore', 'pipe', 'inherit' ], buffer: false } );

proc.stdout.on( 'end', () => console.log( 'stdout ended' ) );
proc.stdout.on( 'close', () => console.log( 'stdout closed' ) );

await proc.catch( e => e );

Only "stdout closed" is logged, "stdout ended" never happens.

This does not match the behavior of child_process:

import { spawn } from 'node:child_process';

const proc = spawn( "does not exist", [], { stdio: [ 'ignore', 'pipe', 'inherit' ] } );

proc.stdout.on( 'end', () => console.log( 'stdout ended' ) );
proc.stdout.on( 'close', () => console.log( 'stdout closed' ) );

proc.on( 'error', () => console.log( 'proc error' ) );

In this case both "stdout ended" and "stdout closed" fire as expected.

[anomiex]

FYI, the code I'm trying to make work looks a bit more like this than the examples above:

import { execa } from 'execa';
import readline from 'readline';

async function* listFiles( dir ) {
    const proc = execa( 'git', [ 'ls-files' ], {
        cwd: dir,
        stdio: [ 'ignore', 'pipe', null ],
        buffer: false
    } );

    const rl = readline.createInterface( {
        input: proc.stdout,
        crlfDelay: Infinity,
    } );

    // We can't allow proc to reject, see https://github.com/sindresorhus/execa/issues/516#issuecomment-1426154012
    // So catch the error and save it to rethrow later.
    let err;
    proc.catch( e => { err = e; } );

    // Yield each line of output.
    yield* rl;

    // If proc rejects, throw the error now.
    await proc;
    if ( err ) throw err;
}

The failure case is if git somehow does not exist in the path.

If you have any better ways to handle this code that don't result in reading the whole output of the command into memory, I'd be happy for the suggestion. The rearrangement suggested by @ehmicky in #516 (comment) doesn't seem compatible with use of yield.

[ehmicky]

Hi @anomiex,

Good catch! I have opened #518 to fix this problem when buffer is false.

[mrienstra]

Released in v7.0.0