Merge pull request rescript-lang#3712 from BuckleScript/npm_link_once

[ci] only do npm link for once

Author: bobzhang

jscomp/build_tests/package.json

@@ -0,0 +1 @@
+{}

scripts/ciTest.js

@@ -140,13 +140,14 @@ function main() {
  if (bsbTest){
  console.log('Doing build_tests')
  var buildTestDir = path.join(__dirname,'..','jscomp','build_tests')
+ cp.execSync(`npm link bs-platform`, {cwd : buildTestDir, stdio:[0,1,2],encoding : 'utf8'})
  var files = fs.readdirSync(buildTestDir)
  files.forEach(function(file){
  var testDir = path.join(buildTestDir, file) 
  if(!fs.existsSync(path.join(testDir,'input.js'))){
  console.warn(`input.js does not exist in ${testDir}`)
  } else {
- cp.execSync(`npm link bs-platform`, {cwd : testDir, stdio:[0,1,2],encoding : 'utf8'})
+ 
  // note existsSync test already ensure that it is a directory
  cp.exec(`node input.js`, {cwd : testDir, encoding : 'utf8'},function (error, stdout, stderr){
  console.log(stdout)