Initial testing framework

tests/unit/jsx-in-js.test.js

@@ -0,0 +1,12 @@
+import { describe, it, expect } from "vitest";
+import React from "react";
+
+function Thing() {
+  return <div>ok</div>;
+}
+
+describe("jsx in .js", () => {
+  it("parses", () => {
+    expect(Thing).toBeTypeOf("function");
+  });
+});