refactor: hasProjectYarn & hasProjectGit

packages/@vue/cli-shared-utils/lib/env.js

@@ -1,7 +1,11 @@
 const { execSync } = require('child_process')
+const fs = require('fs')
+const path = require('path')
 
 let _hasYarn
+const _yarnProjects = new Map()
 let _hasGit
+const _gitProjects = new Map()
 
 // env detection
 exports.hasYarn = () => {
@@ -19,6 +23,22 @@ exports.hasYarn = () => {
   }
 }
 
+exports.hasProjectYarn = (cwd) => {
+  if (_yarnProjects.has(cwd)) {
+    return checkYarn(_yarnProjects.get(cwd))
+  }
+
+  const lockFile = path.join(cwd, 'yarn.lock')
+  const result = fs.existsSync(lockFile)
+  _yarnProjects.set(cwd, result)
+  return checkYarn(result)
+}
+
+function checkYarn (result) {
+  if (result && !exports.hasYarn()) throw new Error(`The project seems to require yarn but it's not installed.`)
+  return result
+}
+
 exports.hasGit = () => {
   if (process.env.VUE_CLI_TEST) {
     return true
@@ -33,3 +53,20 @@ exports.hasGit = () => {
     return (_hasGit = false)
   }
 }
+
+exports.hasProjectGit = (cwd) => {
+  if (_gitProjects.has(cwd)) {
+    return _gitProjects.get(cwd)
+  }
+
+  let result
+  try {
+    execSync('git status', { stdio: 'ignore', cwd })
+    result = true
+  } catch (e) {
+    result = false
+  }
+  console.log('hasProjectGit', cwd, result)
+  _gitProjects.set(cwd, result)
+  return result
+}