Fix: The hashed version of the vite manifests does not change

Root cause: Hash was computed on array.toString() which does not change much.
Solution: Use the actual content of the vite manifests to compute the version.

spec/headers_test.js

@@ -52,7 +52,7 @@ describe('Responses contain custom headers', () => {
   it('index.html has version', async () => {
     const response = await request(app).get('/index.html')
     expect(response.statusCode).toBe(200)
-    expect(response.headers.version).toMatch(/\d*\.3220550168/)
+    expect(response.headers.version).toMatch(/\d*\.\d*/)
   })
 
   it('javascript file contains dependencies', async () => {

spec/util_test.js

+import { describe, it, expect } from '@jest/globals'
+import { hash } from '../src/util'
+import { generateSimpleViteManifest } from './util'
+
+describe('Util', function () {
+  describe('hash function', function () {
+    it('computes the hash', function () {
+      const manifest = generateSimpleViteManifest({
+        'example.js': { imports: ['test.css'] },
+        'test.css': { }
+      })
+      expect(hash(manifest)).toEqual('2245696177')
+    })
+
+    it('the hash changes when the manifest changes', function () {
+      const manifest = generateSimpleViteManifest({
+        'example.js': { imports: ['test.css'] },
+        'test.css': { }
+      })
+      const manifestChanged = generateSimpleViteManifest({
+        'example.js': { imports: ['test1.css'] },
+        'test1.css': { }
+      })
+
+      expect(hash(manifest)).not.toEqual(hash(manifestChanged))
+      expect(hash(manifest)).toEqual('2245696177')
+      expect(hash(manifestChanged)).toEqual('2547998666')
+    })
+  })
+})

src/util.js

 // totaly awesome hash function. Do not use this for encryption (crypto.subtle.digest etc would be overkill for this)
 export function hash (array) {
-  const string = array.toString()
+  const string = JSON.stringify(array)
   if (!string.length) throw new Error('TypeError: Unexpected data to calculate hash from')
 
   let hash = 0