refactor: organize app extensions

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

frontend/src/extensions/external-lib-app-extensions/katex/katex-frame.spec.tsx

@@ -0,0 +1,64 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import KatexFrame from './katex-frame'
+import { render } from '@testing-library/react'
+import type { KatexOptions } from 'katex'
+import { default as KatexDefault } from 'katex'
+
+jest.mock('katex')
+
+describe('katex frame', () => {
+  afterAll(() => {
+    jest.resetAllMocks()
+    jest.resetModules()
+  })
+
+  beforeEach(() => {
+    jest.spyOn(KatexDefault, 'renderToString').mockImplementation(
+      (tex: string, options?: KatexOptions) => `<span>This is a mock for lib katex with this parameters:</span>
+<span>
+  <span>tex: ${tex}</span>
+  <span>block: ${String(options?.displayMode)}</span>
+</span>`
+    )
+  })
+
+  describe('renders a valid latex expression', () => {
+    it('as implicit inline', () => {
+      const view = render(<KatexFrame expression={'\\int_0^\\infty x^2 dx'}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+    it('as explicit inline', () => {
+      const view = render(<KatexFrame expression={'\\int_0^\\infty x^2 dx'} block={false}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+    it('as explicit block', () => {
+      const view = render(<KatexFrame expression={'\\int_0^\\infty x^2 dx'} block={true}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+  })
+
+  describe('renders an error for an invalid latex expression', () => {
+    beforeEach(() => {
+      jest.spyOn(KatexDefault, 'renderToString').mockImplementation(() => {
+        throw new Error('mocked parseerror')
+      })
+    })
+
+    it('as implicit inline', () => {
+      const view = render(<KatexFrame expression={'\\alf'}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+    it('as explicit inline', () => {
+      const view = render(<KatexFrame expression={'\\alf'} block={false}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+    it('as explicit block', () => {
+      const view = render(<KatexFrame expression={'\\alf'} block={true}></KatexFrame>)
+      expect(view.container).toMatchSnapshot()
+    })
+  })
+})