[fix] node v10.0 lacks fs.promises

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

Maybe fixes npm#2623. Maybe fixes npm#2652. Maybe fixes npm#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: ['10.1', 10.x, '12.1', 12.x, '14.1', 14.x]
         script:
         - 'test'
         platform:

lib/shrinkwrap.js

@@ -1,5 +1,7 @@
 const { resolve, basename } = require('path')
-const { promises: { unlink } } = require('fs')
+const util = require('util')
+const fs = require('fs')
+const { unlink } = fs.promises || util.promisify(fs.unlink)
 const Arborist = require('@npmcli/arborist')
 const log = require('npmlog')
 

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 => {