backend/tests/math-transformer.test.ts

/**
 * Math transformer tests.
 *
 * `@tiptap/extension-mathematics` only emits empty placeholders in its static
 * `renderHTML`, so the publisher must render them server-side. These tests
 * exercise the full publish path (renderArticleHTML) to guarantee the
 * published article contains rendered KaTeX, never raw LaTeX or empty nodes.
 */
import { describe, it, expect } from "vitest";
import { renderArticleHTML, type PublishMeta } from "../src/publisher/html-renderer.js";
import type { PublishCSS } from "../src/publisher/index.js";

const EMPTY_CSS: PublishCSS = {
  variables: "",
  reset: "",
  base: "",
  layout: "",
  print: "",
  editorTokens: "",
  article: "",
  components: "",
  publisher: "",
};

const META: PublishMeta = {
  title: "Math Article",
  description: "A test article with math",
  authors: [{ name: "Alice", affiliationIndices: [1], affiliationNames: ["MIT"] }],
  affiliations: [{ name: "MIT" }],
  date: "2025-01-01",
};

const doc = (content: any[]) => ({ type: "doc", content });

describe("math transformer", () => {
  it("renders an inline math placeholder into static KaTeX", async () => {
    const json = doc([
      {
        type: "paragraph",
        content: [
          { type: "text", text: "Energy is " },
          { type: "inlineMath", attrs: { latex: "E = mc^2" } },
          { type: "text", text: " famously." },
        ],
      },
    ]);
    const html = await renderArticleHTML(json, META, EMPTY_CSS);

    expect(html).toContain('class="katex"');
    // KaTeX keeps the source in a MathML annotation, which is expected.
    expect(html).toContain("E = mc^2");
  });

  it("renders a block math placeholder in display mode", async () => {
    const json = doc([{ type: "blockMath", attrs: { latex: "\\int_0^1 x\\,dx = \\frac{1}{2}" } }]);
    const html = await renderArticleHTML(json, META, EMPTY_CSS);

    expect(html).toContain('class="katex"');
    expect(html).toContain("katex-display");
  });

  it("does not throw on malformed LaTeX (renders an error node instead)", async () => {
    const json = doc([
      { type: "paragraph", content: [{ type: "inlineMath", attrs: { latex: "\\frac{" } }] },
    ]);
    const html = await renderArticleHTML(json, META, EMPTY_CSS);

    expect(html).toContain("katex");
  });

  it("drops empty math placeholders so they leave no invisible gap", async () => {
    const json = doc([
      { type: "paragraph", content: [{ type: "inlineMath", attrs: { latex: "" } }] },
    ]);
    const html = await renderArticleHTML(json, META, EMPTY_CSS);

    expect(html).not.toContain('data-type="inline-math"');
  });
});