repo_description: Process execution for humans
repo_topics: binary child-process exec execute javascript nodejs shell spawn spawned-processes streams
code: import mergeStreams from '@sindresorhus/merge-streams';
  import {waitForSubprocessStream} from './stdio.js';
  
  // `all` interleaves `stdout` and `stderr`
  export const makeAllStream = ({stdout, stderr}, {all}) => all && (stdout || stderr)
  	? mergeStreams([stdout, stderr].filter(Boolean))
  	: undefined;
  
  // Read the contents of `subprocess.all` and|or wait for its completion
  export const waitForAllStream = ({subprocess, encoding, buffer, maxBuffer, lines, stripFinalNewline, verboseInfo, streamInfo}) => waitForSubprocessStream({
  	...getAllStream(subprocess, buffer),
  	fdNumber: 'all',
  	encoding,
  	maxBuffer: maxBuffer[1] + maxBuffer[2],
  	lines: lines[1] || lines[2],
  	allMixed: getAllMixed(subprocess),
  	stripFinalNewline,
  	verboseInfo,
  	streamInfo,
  });
  
  const getAllStream = ({stdout, stderr, all}, [, bufferStdout, bufferStderr]) => {
  	const buffer = bufferStdout || bufferStderr;
  	if (!buffer) {
  		return {stream: all, buffer};
  	}
  
  	if (!bufferStdout) {
  		return {stream: stderr, buffer};
  	}
  
  	if (!bufferStderr) {
  		return {stream: stdout, buffer};
  	}
  
  	return {stream: all, buffer};
  };
  
  // When `subprocess.stdout` is in objectMode but not `subprocess.stderr` (or the opposite), we need to use both:
  //  - `getStreamAsArray()` for the chunks in objectMode, to return as an array without changing each chunk
  //  - `getStreamAsArrayBuffer()` or `getStream()` for the chunks not in objectMode, to convert them from Buffers to string or Uint8Array
  // We do this by emulating the Buffer -> string|Uint8Array conversion performed by `get-stream` with our own, which is identical.
  const getAllMixed = ({all, stdout, stderr}) => all
  	&& stdout
  	&& stderr
  	&& stdout.readableObjectMode !== stderr.readableObjectMode;
  