feat: skip postinstall steps when templateVersion has not changed

bin/postinstall.js

@@ -14,9 +14,11 @@ const main = async () => {
 
   const root = dirname(pkgPath)
 
-  await patchPackage(root)
-  await copyContent(root)
-  return installPackages(root)
+  const needsAction = await patchPackage(root)
+  if (needsAction) {
+    await copyContent(root)
+    return installPackages(root)
+  }
 }
 
 // we export the promise so it can be awaited in tests

lib/package.js

@@ -1,9 +1,12 @@
 const PackageJson = require('@npmcli/package-json')
 
+const TEMPLATE_VERSION = require('../package.json').version
+
 const changes = {
   author: 'GitHub Inc.',
   files: ['bin', 'lib'],
   license: 'ISC',
+  templateVersion: TEMPLATE_VERSION,
   scripts: {
     lint: `eslint '**/*.js'`,
     lintfix: 'npm run lint -- --fix',
@@ -19,9 +22,24 @@ const changes = {
 const patchPackage = async (root) => {
   const pkg = await PackageJson.load(root)
 
-  pkg.update(changes)
+  // if the target package.json has a templateVersion field matching our own
+  // current version, we return false here so the postinstall script knows to
+  // exit early instead of running everything again
+  if (pkg.content.templateVersion === TEMPLATE_VERSION) {
+    return false
+  }
+
+  // we build a new object here so our exported set of changes is not modified
+  pkg.update({
+    ...changes,
+    scripts: {
+      ...pkg.content.scripts,
+      ...changes.scripts,
+    },
+  })
 
-  return pkg.save()
+  await pkg.save()
+  return true
 }
 patchPackage.changes = changes
 

package.json

@@ -11,7 +11,8 @@
     "prepublishOnly": "git push origin --follow-tags",
     "snap": "tap",
     "test": "tap",
-    "posttest": "npm run lint"
+    "posttest": "npm run lint",
+    "postinstall": "bin/postinstall.js"
   },
   "repository": {
     "type": "git",
@@ -38,5 +39,6 @@
     "eslint-plugin-node": "^11.1.0",
     "spawk": "^1.7.1",
     "tap": "^15.0.9"
-  }
+  },
+  "templateVersion": "1.0.0"
 }

test/package.js

@@ -2,6 +2,8 @@ const { join } = require('path')
 const fs = require('@npmcli/fs')
 const t = require('tap')
 
+const TEMPLATE_VERSION = require('../package.json').version
+
 const patchPackage = require('../lib/package.js')
 
 t.test('can patch a package.json', async (t) => {
@@ -11,16 +13,45 @@ t.test('can patch a package.json', async (t) => {
     author: 'someone else',
     files: [],
     license: 'MIT',
+    scripts: {
+      foo: 'echo bar',
+    },
+  }
+
+  const project = t.testdir({
+    'package.json': JSON.stringify(pkg, null, 2),
+  })
+
+  const needsAction = await patchPackage(project)
+  t.equal(needsAction, true, 'returned true')
+
+  const contents = await fs.readFile(join(project, 'package.json'), {
+    encoding: 'utf8',
+  })
+  const parsed = JSON.parse(contents)
+  t.match(parsed, patchPackage.changes, 'all changes were applied')
+  t.equal(parsed.scripts.foo, 'echo bar', 'did not remove existing script')
+})
+
+t.test('returns false when templateVersion matches own version', async (t) => {
+  const pkg = {
+    name: '@npmcli/foo',
+    templateVersion: TEMPLATE_VERSION,
+    version: '1.0.0',
+    author: 'someone else',
+    files: [],
+    license: 'MIT',
   }
 
   const project = t.testdir({
     'package.json': JSON.stringify(pkg, null, 2),
   })
 
-  await patchPackage(project)
+  const needsAction = await patchPackage(project)
+  t.equal(needsAction, false, 'returned false')
 
   const contents = await fs.readFile(join(project, 'package.json'), {
     encoding: 'utf8',
   })
-  t.match(JSON.parse(contents), patchPackage.changes, 'all changes were applied')
+  t.notMatch(JSON.parse(contents), patchPackage.changes, 'changes were NOT applied')
 })

test/postinstall.js

@@ -3,6 +3,8 @@ const fs = require('@npmcli/fs')
 const spawk = require('spawk')
 const t = require('tap')
 
+const TEMPLATE_VERSION = require('../package.json').version
+
 const copyContents = require('../lib/content/index.js')
 const installPackages = require('../lib/install.js')
 const patchPackage = require('../lib/package.js')
@@ -32,6 +34,35 @@ t.test('when npm_package_json is unset logs stack and sets exitCode', async (t)
   t.equal(process.exitCode, 1, 'set process.exitCode')
 })
 
+t.test('when patchPackage returns false no further action is taken', async (t) => {
+  const pkg = {
+    name: '@npmcli/foo-test',
+    templateVersion: TEMPLATE_VERSION,
+  }
+
+  // normalize is necessary here until https://github.com/tapjs/libtap/pull/40
+  // is shipped in a new release of tap, otherwise the spawk interceptors
+  // below will not match and tests will fail in windows
+  const root = normalize(t.testdir({
+    'package.json': JSON.stringify(pkg, null, 2),
+  }))
+
+  const _env = process.env.npm_package_json
+  process.env.npm_package_json = join(root, 'package.json')
+
+  t.teardown(() => {
+    process.env.npm_package_json = _env
+  })
+
+  // t.mock instead of require so the cache doesn't interfere
+  // this will reject if actions are taken due to spawk preventing unmatched
+  // spawn calls
+  await t.mock('../bin/postinstall.js')
+  // not setting process.exitCode tells us that the postinstall script
+  // finished successfully since it would be set if it failed
+  t.equal(process.exitCode, undefined, 'did not set process.exitCode')
+})
+
 t.test('sets up a new project', async (t) => {
   const pkg = {
     name: '@npmcli/foo-test',