Tests: convert mocha hooks (#3450)

.mocharc.jsonc

@@ -2,5 +2,6 @@
   "parallel": true,
   "slow": 1000,
   "timeout": 30000,
+  "require": "./test/beforeEach.js",
   "spec": "./test/unit/*.js"
 }

test/beforeEach.js

@@ -1,7 +1,7 @@
 'use strict';
 
 const detectLibc = require('detect-libc');
-const sharp = require('../../');
+const sharp = require('../');
 
 const libcFamily = detectLibc.familySync();
 const usingCache = !(process.env.G_DEBUG || libcFamily === detectLibc.MUSL);
@@ -9,14 +9,16 @@ const usingSimd = !(process.env.G_DEBUG || process.env.VIPS_NOVECTOR);
 const concurrency = process.env.VIPS_CONCURRENCY ||
   (libcFamily === detectLibc.MUSL || process.arch === 'arm' ? 1 : undefined);
 
-beforeEach(function () {
+exports.mochaHooks = {
+  beforeEach () {
     sharp.cache(usingCache);
     sharp.simd(usingSimd);
     sharp.concurrency(concurrency);
-});
+  },
 
-afterEach(function () {
+  afterEach () {
     if (global.gc) {
       global.gc();
     }
-});
+  }
+};