fix: -v flag not working for yarn@berry (#175)

Author: Dimava

src/runner.ts

@@ -12,7 +12,7 @@ import { getDefaultAgent, getGlobalAgent } from './config'
 import type { DetectOptions } from './detect'
 import { detect } from './detect'
 import { getVoltaPrefix, remove } from './utils'
-import { UnsupportedCommand } from './parse'
+import { UnsupportedCommand, getCommand } from './parse'
 
 const DEBUG_SIGN = '?'
 
@@ -84,8 +84,9 @@ export async function run(fn: Runner, args: string[], options: DetectOptions = {
     args.splice(0, 2)
   }
 
-  if (args.length === 1 && (args[0]?.toLowerCase() === '-v')) {
-    const getV = (a: string, o?: ExecaOptions) => execaCommand(`${a} -v`, o).then(e => e.stdout).then(e => e.startsWith('v') ? e : `v${e}`)
+  if (args.length === 1 && (args[0]?.toLowerCase() === '-v' || args[0] === '--version')) {
+    const getCmd = (a: Agent) => agents.includes(a) ? getCommand(a, 'agent', ['-v']) : `${a} -v`
+    const getV = (a: string, o?: ExecaOptions) => execaCommand(getCmd(a as Agent), o).then(e => e.stdout).then(e => e.startsWith('v') ? e : `v${e}`)
     const globalAgentPromise = getGlobalAgent()
     const globalAgentVersionPromise = globalAgentPromise.then(getV)
     const agentPromise = detect({ ...options, cwd }).then(a => a || '')
@@ -112,13 +113,14 @@ export async function run(fn: Runner, args: string[], options: DetectOptions = {
   if (args.length === 1 && ['-h', '--help'].includes(args[0])) {
     const dash = c.dim('-')
     console.log(c.green(c.bold('@antfu/ni')) + c.dim(` use the right package manager v${version}\n`))
-    console.log(`ni   ${dash}  install`)
-    console.log(`nr   ${dash}  run`)
-    console.log(`nlx  ${dash}  execute`)
-    console.log(`nu   ${dash}  upgrade`)
-    console.log(`nun  ${dash}  uninstall`)
-    console.log(`nci  ${dash}  clean install`)
-    console.log(`na   ${dash}  agent alias`)
+    console.log(`ni    ${dash}  install`)
+    console.log(`nr    ${dash}  run`)
+    console.log(`nlx   ${dash}  execute`)
+    console.log(`nu    ${dash}  upgrade`)
+    console.log(`nun   ${dash}  uninstall`)
+    console.log(`nci   ${dash}  clean install`)
+    console.log(`na    ${dash}  agent alias`)
+    console.log(`ni -v ${dash}  show used agent`)
     console.log(c.yellow('\ncheck https://github.com/antfu/ni for more documentation.'))
     return
   }