feat: --use-stderr (#3463)

.changeset/sweet-fireants-sniff.md

@@ -0,0 +1,8 @@
+---
+"@pnpm/config": minor
+"@pnpm/default-reporter": minor
+"@pnpm/common-cli-options-help": minor
+"pnpm": minor
+---
+
+New CLI option added: `use-stderr`. When set, all the output is written to stderr.

packages/common-cli-options-help/src/index.ts

@@ -53,6 +53,10 @@ export const UNIVERSAL_OPTIONS = [
     description: 'Stream output from child processes immediately, prefixed with the originating package directory. This allows output from different packages to be interleaved.',
     name: '--stream',
   },
+  {
+    description: 'Divert all output to stderr',
+    name: '--use-stderr',
+  },
 ]
 export const FILTERING = {
   list: [

packages/config/src/Config.ts

@@ -66,6 +66,7 @@ export interface Config {
   ignoreCurrentPrefs?: boolean
   recursive?: boolean
   enablePrePostScripts?: boolean
+  useStderr?: boolean
 
   // proxy
   httpProxy?: string

packages/config/src/index.ts

@@ -96,6 +96,7 @@ export const types = Object.assign({
   'use-beta-cli': Boolean,
   'use-running-store-server': Boolean,
   'use-store-server': Boolean,
+  'use-stderr': Boolean,
   'verify-store-integrity': Boolean,
   'virtual-store-dir': String,
   'workspace-concurrency': Number,

packages/default-reporter/src/index.ts

@@ -14,6 +14,7 @@ export { formatWarn }
 
 export default function (
   opts: {
+    useStderr?: boolean
     streamParser: object
     reportingOptions?: {
       appendOnly?: boolean
@@ -37,11 +38,14 @@ export default function (
   const outputMaxWidth = opts.reportingOptions?.outputMaxWidth ?? (process.stdout.columns && process.stdout.columns - 2) ?? 80
   const output$ = toOutput$({ ...opts, reportingOptions: { ...opts.reportingOptions, outputMaxWidth } })
   if (opts.reportingOptions?.appendOnly) {
+    const writeNext = opts.useStderr
+      ? console.error.bind(console)
+      : console.log.bind(console)
     output$
       .subscribe({
         complete () {}, // eslint-disable-line:no-empty
         error: (err) => console.error(err.message),
-        next: (line) => console.log(line),
+        next: writeNext,
       })
     return
   }
@@ -55,12 +59,15 @@ export default function (
       error: (err) => logUpdate(err.message),
       next: logUpdate,
     })
+  const write = opts.useStderr
+    ? process.stderr.write.bind(process.stderr)
+    : process.stdout.write.bind(process.stdout)
   function logUpdate (view: string) {
     // A new line should always be appended in case a prompt needs to appear.
     // Without a new line the prompt will be joined with the previous output.
     // An example of such prompt may be seen by running: pnpm update --interactive
     if (!view.endsWith(EOL)) view += EOL
-    process.stdout.write(diff.update(view))
+    write(diff.update(view))
   }
 }
 

packages/pnpm/src/cmd/index.ts

@@ -36,6 +36,7 @@ export const GLOBAL_OPTIONS = R.pick([
   'reporter',
   'stream',
   'test-pattern',
+  'use-stderr',
   'workspace-packages',
   'workspace-root',
 ], allTypes)

packages/pnpm/src/reporter/index.ts

@@ -15,6 +15,7 @@ export default (
   switch (reporterType) {
   case 'default':
     defaultReporter({
+      useStderr: opts.config.useStderr,
       context: {
         argv: opts.cmd ? [opts.cmd] : [],
         config: opts.config,
@@ -30,6 +31,7 @@ export default (
     return
   case 'append-only':
     defaultReporter({
+      useStderr: opts.config.useStderr,
       context: {
         argv: opts.cmd ? [opts.cmd] : [],
         config: opts.config,

packages/pnpm/test/install/misc.ts

@@ -67,6 +67,16 @@ test('install --no-lockfile', async () => {
   expect(await project.readLockfile()).toBeFalsy()
 })
 
+test('write to stderr when --use-stderr is used', async () => {
+  const project = prepare()
+
+  const result = execPnpmSync(['add', 'is-positive', '--use-stderr'])
+
+  await project.has('is-positive')
+  expect(result.stdout.toString()).toBe('')
+  expect(result.stderr.toString()).not.toBe('')
+})
+
 test('install with package-lock=false in .npmrc', async () => {
   const project = prepare()