test: post page view sanitizes the body and drops sources

- body sanitized with its safe text kept, source, translations and
  related post bodies out of the payload, null body as an empty string

tests/postView.test.ts

@@ -0,0 +1,55 @@
+// The post page's payload: the body is sanitized, never blanked, and the raw
+// source, translations and related post bodies stay out of it.
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+import { toPostView } from '../app/utils/postView.ts'
+import type { JournalPost, JournalPostDetail } from '../app/utils/types.ts'
+
+function post(overrides: Partial<JournalPost> = {}): JournalPost {
+  return {
+    id: 1,
+    title: 'Hello',
+    slug: 'hello',
+    excerpt: null,
+    content: 'source',
+    content_html: '<p>Hello</p>',
+    reading_time: 1,
+    published: true,
+    published_at: '2026-01-01T00:00:00+00:00',
+    is_pinned: false,
+    metadata: null,
+    sources: null,
+    author: null,
+    categories: [],
+    tags: [],
+    featured_images: [],
+    featured_image_url: null,
+    translations: { en: { title: 'Hello' } },
+    created_at: null,
+    updated_at: null,
+    ...overrides,
+  }
+}
+
+function detail(overrides: Partial<JournalPostDetail> = {}): JournalPostDetail {
+  return { ...post(), previous_post: null, next_post: null, related_posts: [], ...overrides }
+}
+
+test('the body is sanitized and the safe parts are kept', () => {
+  const view = toPostView(detail({ content_html: '<p>Data: 12 maja 2024</p><script>alert(1)</script><p>After</p>' }))
+  assert.equal(view.content_html, '<p>Data: 12 maja 2024</p><p>After</p>')
+})
+
+test('source, translations and related post bodies stay out of the payload', () => {
+  const view = toPostView(detail({ related_posts: [post({ id: 2, slug: 'other' })] }))
+  assert.equal(view.content, null)
+  assert.equal(view.translations, null)
+  assert.equal(view.related_posts.length, 1)
+  assert.equal(view.related_posts[0]!.content_html, null)
+  assert.equal(view.related_posts[0]!.content, null)
+  assert.equal(view.related_posts[0]!.translations, null)
+})
+
+test('a missing body becomes an empty string', () => {
+  assert.equal(toPostView(detail({ content_html: null })).content_html, '')
+})