feat(extensions): Introduce app extensions

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

src/extensions/extra-integrations/youtube/replace-youtube-link.test.ts

@@ -0,0 +1,54 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { replaceYouTubeLinkMarkdownItPlugin } from './replace-youtube-link'
+import MarkdownIt from 'markdown-it'
+
+describe('Replace youtube link', () => {
+  let markdownIt: MarkdownIt
+
+  beforeEach(() => {
+    markdownIt = new MarkdownIt('default', {
+      html: false,
+      breaks: true,
+      langPrefix: '',
+      typographer: true
+    })
+    markdownIt.use(replaceYouTubeLinkMarkdownItPlugin)
+  })
+  ;['http://', 'https://', ''].forEach((protocol) => {
+    ;['www.', ''].forEach((subdomain) => {
+      ;['youtube.com', 'youtube-nocookie.com'].forEach((domain) => {
+        const origin = `${protocol}${subdomain}${domain}/`
+        describe(origin, () => {
+          const validUrl = `${origin}?v=12312312312`
+          it(`can detect a correct youtube video url`, () => {
+            expect(markdownIt.renderInline(validUrl)).toBe('<app-youtube id="12312312312"></app-youtube>')
+          })
+
+          it("won't detect an URL without video id", () => {
+            expect(markdownIt.renderInline(origin)).toBe(origin)
+          })
+
+          it("won't detect an invalid(too short) youtube id", () => {
+            const invalidUrl = '${origin}?v=1'
+            expect(markdownIt.renderInline(invalidUrl)).toBe(invalidUrl)
+          })
+
+          it("won't detect an invalid(invalid characters) youtube id", () => {
+            const invalidUrl = '${origin}?v= /!#/'
+            expect(markdownIt.renderInline(invalidUrl)).toBe(invalidUrl)
+          })
+
+          it("won't detect an invalid(too long) youtube id", () => {
+            const invalidUrl = '${origin}?v=111111111111111111111111111111111'
+            expect(markdownIt.renderInline(invalidUrl)).toBe(invalidUrl)
+          })
+        })
+      })
+    })
+  })
+})