ShadowRealm: cache importValue module in its own realm under require(esm)

scripts/build/deps/webkit.ts

@@ -3,7 +3,7 @@
  * for local mode. Override via `--webkit-version=<hash>` to test a branch.
  * From https://github.com/oven-sh/WebKit releases.
  */
-export const WEBKIT_VERSION = "549170099226f816a4b204ea1d8fa102fb79eefa";
+export const WEBKIT_VERSION = "autobuild-preview-pr-371-4e9f0037";
 
 /**
  * WebKit (JavaScriptCore) — the JS engine.

test/js/bun/jsc/shadow.test.js

@@ -1,4 +1,5 @@
 import { expect, it } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
 
 it("shadow realm works", () => {
   const red = new ShadowRealm();
@@ -8,3 +9,44 @@ it("shadow realm works", () => {
   expect(globalThis.someValue).toBe(1);
   expect(result).toBe(2);
 });
+
+// require(esm) drives the module loader through a VM-wide synchronous queue.
+// Reactions from a ShadowRealm's own module loader that fire during that drain
+// must be replayed against the ShadowRealm's registry, not the caller's; if
+// they aren't, the first importValue registers the module in the wrong realm
+// and the second importValue loads a fresh copy instead of the cached one.
+it("importValue caches modules in the ShadowRealm when kicked off under require(esm)", async () => {
+  using dir = tempDir("shadow-realm-sync-queue", {
+    "counter.mjs": `let n = 0; export const getCounter = () => n++;`,
+    "trigger.mjs": `
+      import url from "node:url";
+      import path from "node:path";
+      const mod = url.pathToFileURL(path.join(import.meta.dirname, "counter.mjs")).href;
+      const realm = new ShadowRealm();
+      const first = realm.importValue(mod, "getCounter");
+      export { realm, first, mod };
+    `,
+    "entry.cjs": `
+      const { realm, first, mod } = require("./trigger.mjs");
+      (async () => {
+        const a = await first;
+        const b = await realm.importValue(mod, "getCounter");
+        const { getCounter: outer } = await import(mod);
+        console.log(JSON.stringify({ a0: a(), b0: b(), b1: b(), outer: outer() }));
+      })().catch(e => { console.error(e); process.exit(1); });
+    `,
+  });
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "entry.cjs"],
+    env: bunEnv,
+    cwd: String(dir),
+    stderr: "pipe",
+  });
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+  expect(stderr).toBe("");
+  // a and b must share module state inside the ShadowRealm; the outer realm's
+  // import of the same specifier must be a separate instance.
+  expect(JSON.parse(stdout.trim())).toEqual({ a0: 0, b0: 1, b1: 2, outer: 0 });
+  expect(exitCode).toBe(0);
+});