test(extensions): share direct import smoke harness

test/helpers/plugins/direct-smoke.ts

@@ -0,0 +1,25 @@
+import { execFile } from "node:child_process";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { promisify } from "node:util";
+
+const execFileAsync = promisify(execFile);
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..", "..", "..");
+
+const SHARED_IMPORT_ENV = {
+  HOME: process.env.HOME,
+  NODE_OPTIONS: process.env.NODE_OPTIONS,
+  NODE_PATH: process.env.NODE_PATH,
+  PATH: process.env.PATH,
+  TERM: process.env.TERM,
+} satisfies NodeJS.ProcessEnv;
+
+export async function runDirectImportSmoke(code: string): Promise<string> {
+  const { stdout } = await execFileAsync(process.execPath, ["--import", "tsx", "-e", code], {
+    cwd: repoRoot,
+    env: SHARED_IMPORT_ENV,
+    timeout: 40_000,
+  });
+
+  return stdout;
+}