test: migrate tests from centralized mjs to colocated TypeScript

Move test files from tests/ directory to colocate with source code,
convert from .mjs to .ts using tsx runner, add workspaces and npm
cache to CI workflow.

packages/baoyu-md/src/html-builder.test.ts

@@ -0,0 +1,71 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { DEFAULT_STYLE } from "./constants.ts";
+import {
+  buildCss,
+  buildHtmlDocument,
+  modifyHtmlStructure,
+  normalizeCssText,
+  normalizeInlineCss,
+  removeFirstHeading,
+} from "./html-builder.ts";
+
+test("buildCss injects style variables and concatenates base and theme CSS", () => {
+  const css = buildCss("body { color: red; }", ".theme { color: blue; }");
+
+  assert.match(css, /--md-primary-color: #0F4C81;/);
+  assert.match(css, /body \{ color: red; \}/);
+  assert.match(css, /\.theme \{ color: blue; \}/);
+});
+
+test("buildHtmlDocument includes optional meta tags and code theme CSS", () => {
+  const html = buildHtmlDocument(
+    {
+      title: "Doc",
+      author: "Baoyu",
+      description: "Summary",
+    },
+    "body { color: red; }",
+    "<article>Hello</article>",
+    ".hljs { color: blue; }",
+  );
+
+  assert.match(html, /<title>Doc<\/title>/);
+  assert.match(html, /meta name="author" content="Baoyu"/);
+  assert.match(html, /meta name="description" content="Summary"/);
+  assert.match(html, /<style>body \{ color: red; \}<\/style>/);
+  assert.match(html, /<style>\.hljs \{ color: blue; \}<\/style>/);
+  assert.match(html, /<article>Hello<\/article>/);
+});
+
+test("normalizeCssText and normalizeInlineCss replace variables and strip declarations", () => {
+  const rawCss = `
+:root { --md-primary-color: #000; --md-font-size: 12px; --foreground: 0 0% 5%; }
+.box { color: var(--md-primary-color); font-size: var(--md-font-size); background: hsl(var(--foreground)); }
+`;
+
+  const normalizedCss = normalizeCssText(rawCss, DEFAULT_STYLE);
+  assert.match(normalizedCss, /color: #0F4C81/);
+  assert.match(normalizedCss, /font-size: 16px/);
+  assert.match(normalizedCss, /background: #3f3f3f/);
+  assert.doesNotMatch(normalizedCss, /--md-primary-color/);
+
+  const normalizedHtml = normalizeInlineCss(
+    `<style>${rawCss}</style><div style="color: var(--md-primary-color)"></div>`,
+    DEFAULT_STYLE,
+  );
+  assert.match(normalizedHtml, /color: #0F4C81/);
+  assert.doesNotMatch(normalizedHtml, /var\(--md-primary-color\)/);
+});
+
+test("HTML structure helpers hoist nested lists and remove the first heading", () => {
+  const nestedList = `<ul><li>Parent<ul><li>Child</li></ul></li></ul>`;
+  assert.equal(
+    modifyHtmlStructure(nestedList),
+    `<ul><li>Parent</li><ul><li>Child</li></ul></ul>`,
+  );
+
+  const html = `<h1>Title</h1><p>Intro</p><h2>Sub</h2>`;
+  assert.equal(removeFirstHeading(html), `<p>Intro</p><h2>Sub</h2>`);
+});