test(e2e): add cypress test for license frontmatter

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

frontend/cypress/e2e/note-meta-head.spec.ts

@@ -0,0 +1,47 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+describe('Opengraph metadata', () => {
+  beforeEach(() => {
+    cy.visitTestNote()
+  })
+
+  it('includes the note title if not overridden', () => {
+    cy.setCodemirrorContent('---\ntitle: Test title\n---')
+    cy.get('meta[property="og:title"]').should('have.attr', 'content', 'Test title')
+  })
+
+  it('includes the note title if overridden', () => {
+    cy.setCodemirrorContent('---\ntitle: Test title\nopengraph:\n  title: Overridden title\n---')
+    cy.get('meta[property="og:title"]').should('have.attr', 'content', 'Overridden title')
+  })
+
+  it('includes custom opengraph tags', () => {
+    cy.setCodemirrorContent('---\nopengraph:\n  image: https://dummyimage.com/48\n---')
+    cy.get('meta[property="og:image"]').should('have.attr', 'content', 'https://dummyimage.com/48')
+  })
+})
+
+describe('License frontmatter', () => {
+  beforeEach(() => {
+    cy.visitTestNote()
+  })
+
+  it('sets the link tag if defined and not blank', () => {
+    cy.setCodemirrorContent('---\nlicense: https://example.com\n---')
+    cy.get('link[rel="license"]').should('have.attr', 'href', 'https://example.com')
+  })
+
+  it('does not set the link tag if not defined', () => {
+    cy.setCodemirrorContent('---\ntitle: No license for this note\n---')
+    cy.get('link[rel="license"]').should('not.exist')
+  })
+
+  it('does not set the link tag if defined but blank', () => {
+    cy.setCodemirrorContent('---\nlicense: \n---')
+    cy.get('link[rel="license"]').should('not.exist')
+  })
+})