improve rrdom robustness (#1091)

packages/rrdom/test/utils.ts

@@ -0,0 +1,26 @@
+import * as rollup from 'rollup';
+import * as typescript from 'rollup-plugin-typescript2';
+import resolve from '@rollup/plugin-node-resolve';
+const _typescript = (typescript as unknown) as typeof typescript.default;
+
+/**
+ * Use rollup to compile an input TS script into JS code string.
+ */
+export async function compileTSCode(inputFilePath: string) {
+  const bundle = await rollup.rollup({
+    input: inputFilePath,
+    plugins: [
+      (resolve() as unknown) as rollup.Plugin,
+      (_typescript({
+        tsconfigOverride: { compilerOptions: { module: 'ESNext' } },
+      }) as unknown) as rollup.Plugin,
+    ],
+  });
+  const {
+    output: [{ code: _code }],
+  } = await bundle.generate({
+    name: 'rrdom',
+    format: 'iife',
+  });
+  return _code;
+}