[fix] node v10.0 lacks fs.promises

In this node version, fall back to `util.promisify` of the callback version.

Maybe fixes #2623. Maybe fixes #2652. Maybe fixes #2625.

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [10.x, 12.x, 14.x]
+        node-version: ['10.0', 10.x, '12.0', 12.x, '14.0', 14.x]
         platform:
         - os: ubuntu-latest
           shell: bash

lib/utils/reify-finish.js

@@ -1,7 +1,9 @@
 const reifyOutput = require('./reify-output.js')
 const npm = require('../npm.js')
 const ini = require('ini')
-const {writeFile} = require('fs').promises
+const util = require('util')
+const fs = require('fs')
+const { writeFile } = fs.promises || { writeFile: util.promisify(fs.writeFile) }
 const {resolve} = require('path')
 
 const reifyFinish = async arb => {

test/lib/utils/reify-finish.js

@@ -78,3 +78,11 @@ t.test('should write if everything above passes', async t => {
   const data = fs.readFileSync(`${path}/npmrc`, 'utf8').replace(/\r\n/g, '\n')
   t.matchSnapshot(data, 'written config')
 })
+
+t.test('works without fs.promises', async t => {
+  t.doesNotThrow(() => requireInject('../../../lib/utils/reify-finish.js', {
+    fs: { ...fs, promises: null },
+    '../../../lib/npm.js': npm,
+    '../../../lib/utils/reify-output.js': reifyOutput,
+  }))
+})