ShadowRealm: importValue resolves an export whose value is undefined (WebKit bump for oven-sh/WebKit#612)

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 = "2e2aa2290fac856d6f451ceacb58f7f5b44dd057";
+export const WEBKIT_VERSION = "autobuild-preview-pr-612-43d09378";
 
 /**
  * WebKit (JavaScriptCore) — the JS engine.

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

@@ -1,4 +1,6 @@
-import { expect, it } from "bun:test";
+import { describe, expect, it } from "bun:test";
+import { tempDir } from "harness";
+import { join } from "node:path";
 
 it("shadow realm works", () => {
   const red = new ShadowRealm();
@@ -8,3 +10,38 @@ it("shadow realm works", () => {
   expect(globalThis.someValue).toBe(1);
   expect(result).toBe(2);
 });
+
+describe("importValue", () => {
+  // https://tc39.es/proposal-shadowrealm/#sec-export-getter-functions checks HasOwnProperty(exports, name), then reads
+  // the value. An export whose value is undefined exists.
+  it("resolves an export whose value is undefined", async () => {
+    using dir = tempDir("shadow-realm-import-value", {
+      "mod.mjs": `
+        export const undefinedValue = undefined;
+        export let notYet;
+        export function setNotYet(v) { notYet = v; }
+        export const nullValue = null;
+      `,
+    });
+    const mod = join(String(dir), "mod.mjs");
+    const realm = new ShadowRealm();
+    expect(await realm.importValue(mod, "undefinedValue")).toBe(undefined);
+    expect(await realm.importValue(mod, "nullValue")).toBe(null);
+    // A live binding that is still undefined reads its current value each time.
+    expect(await realm.importValue(mod, "notYet")).toBe(undefined);
+    (await realm.importValue(mod, "setNotYet"))("now");
+    expect(await realm.importValue(mod, "notYet")).toBe("now");
+    // A name that is not exported still rejects. That includes names an ordinary object would inherit, and __esModule,
+    // which Bun's module namespace objects inherit from their prototype: the check is HasOwnProperty.
+    for (const name of ["missing", "toString", "__proto__", "constructor", "then", "__esModule"]) {
+      let error;
+      try {
+        await realm.importValue(mod, name);
+      } catch (e) {
+        error = e;
+      }
+      expect(error).toBeInstanceOf(TypeError);
+      expect(error.message).toBe("%ShadowRealm%.importValue requires |exportName| to exist in the |specifier|");
+    }
+  });
+});