vitest setup

package.json

@@ -6,5 +6,8 @@
     "patchedDependencies": {
       "[email protected]": "patches/[email protected]"
     }
+  },
+  "devDependencies": {
+    "vitest": "^1.6.0"
   }
 }

packages/server/src/rewrite.test.ts

@@ -0,0 +1,14 @@
+import { expect, it } from "vitest";
+import rewrite from "./rewrite";
+
+it("rewrites", () => {
+  const code = "{ foo: 'bar' }";
+  const language = "typescript";
+  const id = "id";
+  const cellId = "cellId";
+  const cells = new Map();
+
+  const result = rewrite(code, language, id, cellId, cells);
+
+  expect(result.code).toEqual("export default {\n  foo: 'bar'\n};");
+});

packages/server/src/rewrite.ts

@@ -4,8 +4,16 @@ import * as babelParser from "@babel/parser";
 import _babelTraverse from "@babel/traverse";
 import * as babelTypes from "@babel/types";
 import type { Cell, SourceDescription } from "./types";
-const babelGenerator: typeof _babelGenerator = (_babelGenerator as any).default;
-const babelTraverse: typeof _babelTraverse = (_babelTraverse as any).default;
+
+// ESM / CJS interop nonsense
+const babelGenerator: typeof _babelGenerator =
+  typeof _babelGenerator === "function"
+    ? _babelGenerator
+    : (_babelGenerator as any).default;
+const babelTraverse: typeof _babelTraverse =
+  typeof _babelTraverse === "function"
+    ? _babelTraverse
+    : (_babelTraverse as any).default;
 
 const reactImports = babelParser.parse(
   `