feat: detect yarn according to yarn.lock (#872)

* feat: detect yarn according to yarn.lock

* Move autoyarn logic to initOptions.

* Allow cli to override autoyarn.

Co-authored-by: Raine Revere <[email protected]>

Author: Tchoupinax

bin/cli.js

@@ -82,7 +82,7 @@ const combinedArguments = rcResult
 
 program.parse(combinedArguments)
 
-// filter out undefined program options and combine with config file options
+// filter out undefined program options and combine cli options with config file options
 const options = {
   ...rcResult && Object.keys(rcResult.config).length > 0
     ? { rcConfigPath: rcResult.filePath }
@@ -93,4 +93,6 @@ const options = {
   cli: true,
 }
 
+// NOTE: Options handling and defaults go in initOptions in index.js
+
 ncu.run(options)

lib/cli-options.js

@@ -182,8 +182,8 @@ const cliOptions = [
     long: 'packageManager',
     short: 'p',
     arg: 'name',
-    description: 'npm, yarn',
-    default: 'npm'
+    // manual default to allow overriding auto yarn detection
+    description: 'npm, yarn (default: "npm")'
   },
   {
     long: 'pre',

lib/index.js

@@ -297,6 +297,13 @@ function initOptions(options) {
     ...options.ownerChanged ? ['ownerChanged'] : []
   ]
 
+  // autodetect yarn
+  const files = fs.readdirSync(options.cwd || '.')
+  const autoYarn = !options.packageManager && files.includes('yarn.lock') && !files.includes('package-lock.json')
+  if (autoYarn) {
+    print(options, 'Using yarn')
+  }
+
   return {
     ...options,
     ...options.deep ? { packageFile: `${deepPatternPrefix}${getPackageFileName(options)}` } : null,
@@ -314,6 +321,7 @@ function initOptions(options) {
     target,
     // imply upgrade in interactive mode when json is not specified as the output
     ...options.interactive && options.upgrade === undefined ? { upgrade: !json } : null,
+    ...!options.packageManager && { packageManager: autoYarn ? 'yarn' : 'npm' },
   }
 }