fix node 6 support

package.json

@@ -54,7 +54,7 @@
     "eslint-config-simenb-base": "^15.0.1",
     "eslint_d": "^7.1.0",
     "express": "^4.17.1",
-    "html-webpack-plugin": "^4.0.0-0",
+    "html-webpack-plugin": "^4.0.0",
     "husky": "^1.0.1",
     "jest": "^24.0.0",
     "jest-watch-typeahead": "^0.2.0",
@@ -67,7 +67,7 @@
     "webpack-cli": "^3.1.0"
   },
   "peerDependencies": {
-    "html-webpack-plugin": "^3.0.4 || ^4.0.0-0 || ^5.0.0-0",
+    "html-webpack-plugin": "^3.0.4 || ^4.0.0-0 || ^5.0.0",
     "webpack": "^4.0.0 || ^5.0.0"
   },
   "engines": {

src/index.js

@@ -3,19 +3,17 @@ import pEachSeries from 'p-each-series';
 import micromatch from 'micromatch';
 import crypto from 'crypto';
 import globby from 'globby';
-import fs from 'fs';
 import path from 'path';
 import webpack from 'webpack';
-import { promisify } from 'util';
 import {
   ensureTrailingSlash,
+  fsReadFileAsync,
   handleUrl,
   resolveOutput,
   resolvePublicPath,
 } from './utils';
 
-const fsReadFileAsync = promisify(fs.readFile);
-
+/* istanbul ignore next: webpack 5 not in unit test mocks */
 /**
  * Pushes the content of the given filename to the compilation assets
  * @param {string} filename
@@ -135,9 +133,11 @@ export default class AddAssetHtmlPlugin {
       }
     }
 
-    const addedFilename = await (
-      htmlPluginData.plugin.addFileToAssets || addFileToAssetsWebpack5
-    )(filepath, compilation);
+    const addFileToAssets =
+      htmlPluginData.plugin.addFileToAssets ||
+      /* istanbul ignore next: webpack 5 not in unit test mocks */ addFileToAssetsWebpack5;
+
+    const addedFilename = await addFileToAssets(filepath, compilation);
 
     let suffix = '';
     if (hash) {
@@ -162,9 +162,10 @@ export default class AddAssetHtmlPlugin {
       const relatedFiles = await globby(`${filepath}.*`);
       await Promise.all(
         relatedFiles.sort().map(async relatedFile => {
-          const addedMapFilename = await (
-            htmlPluginData.plugin.addFileToAssets || addFileToAssetsWebpack5
-          )(relatedFile, compilation);
+          const addedMapFilename = await addFileToAssets(
+            relatedFile,
+            compilation,
+          );
           resolveOutput(compilation, addedMapFilename, outputPath);
         }),
       );

src/utils.js

@@ -1,5 +1,6 @@
 import path from 'path';
 import globby from 'globby';
+import fs from 'fs';
 
 export function ensureTrailingSlash(string) {
   if (string.length && string.substr(-1, 1) !== '/') {
@@ -30,6 +31,19 @@ export function resolveOutput(compilation, addedFilename, outputPath) {
   }
 }
 
+/* istanbul ignore next: webpack 5 not in unit test mocks */
+export function fsReadFileAsync(filePath) {
+  return new Promise((resolve, reject) => {
+    fs.readFile(filePath, (err, res) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(res);
+      }
+    });
+  });
+}
+
 /**
  * handle globby filepath and return an array with all matched assets.
  *

yarn.lock

@@ -3869,7 +3869,7 @@ html-minifier-terser@^5.0.1:
     relateurl "^0.2.7"
     terser "^4.6.3"
 
-html-webpack-plugin@^4.0.0-0:
+html-webpack-plugin@^4.0.0:
   version "4.5.2"
   resolved "https://registry.yarnpkg.com/html-webpack-plugin/-/html-webpack-plugin-4.5.2.tgz#76fc83fa1a0f12dd5f7da0404a54e2699666bc12"
   integrity sha512-q5oYdzjKUIPQVjOosjgvCHQOv9Ett9CYYHlgvJeXG0qQvdSojnBq4vAdQBwn1+yGveAwHCoe/rMR86ozX3+c2A==