fix: provide nodejs compat for dns methods wrapped with util.promisify (#6748)

* fix: add nodejs compat for dns methods wrapping with util.promisify

* fix: use single symbol for util.promisify.custom

* style: linting

4 files changed, 53 insertions, 2 deletions

diff --git a/src/js/node/dns.js b/src/js/node/dns.js
index e82e6a4b5..3f8787742 100644
--- a/src/js/node/dns.js
+++ b/src/js/node/dns.js
@@ -1,6 +1,7 @@
 // Hardcoded module "node:dns"
 // only resolve4, resolve, lookup, resolve6, resolveSrv, and reverse are implemented.
 const dns = Bun.dns;
+const utilPromisifyCustomSymbol = Symbol.for("nodejs.util.promisify.custom");
 
 function getServers() {
   return dns.getServers();
@@ -683,6 +684,28 @@ for (const key of ["resolveAny"]) {
   promises[key] = () => Promise.resolve(undefined);
 }
 
+// Compatibility with util.promisify(dns[method])
+for (const [method, pMethod] of [
+  [lookup, promises.lookup],
+  [lookupService, promises.lookupService],
+  [resolve, promises.resolve],
+  [reverse, promises.reverse],
+  [resolve4, promises.resolve4],
+  [resolve6, promises.resolve6],
+  [resolveAny, promises.resolveAny],
+  [resolveCname, promises.resolveCname],
+  [resolveCaa, promises.resolveCaa],
+  [resolveMx, promises.resolveMx],
+  [resolveNs, promises.resolveNs],
+  [resolvePtr, promises.resolvePtr],
+  [resolveSoa, promises.resolveSoa],
+  [resolveSrv, promises.resolveSrv],
+  [resolveTxt, promises.resolveTxt],
+  [resolveNaptr, promises.resolveNaptr],
+]) {
+  method[utilPromisifyCustomSymbol] = pMethod;
+}
+
 export default {
   // these are wrong
   ADDRCONFIG: 0,
diff --git a/src/js/node/util.js b/src/js/node/util.js
index dae341448..2002eed25 100644
--- a/src/js/node/util.js
+++ b/src/js/node/util.js
@@ -147,7 +147,7 @@ var _extend = function (origin, add) {
   }
   return origin;
 };
-var kCustomPromisifiedSymbol = Symbol.for("util.promisify.custom");
+var kCustomPromisifiedSymbol = Symbol.for("nodejs.util.promisify.custom");
 var promisify = function promisify(original) {
   if (typeof original !== "function") throw new TypeError('The "original" argument must be of type Function');
   if (kCustomPromisifiedSymbol && original[kCustomPromisifiedSymbol]) {
diff --git a/test/js/node/dns/node-dns.test.js b/test/js/node/dns/node-dns.test.js
index 1988e9155..edf58308a 100644
--- a/test/js/node/dns/node-dns.test.js
+++ b/test/js/node/dns/node-dns.test.js
@@ -3,6 +3,7 @@ import * as dns from "node:dns";
 import * as dns_promises from "node:dns/promises";
 import * as fs from "node:fs";
 import * as os from "node:os";
+import * as util from "node:util";
 
 // TODO:
 test("it exists", () => {
@@ -405,3 +406,31 @@ describe("lookup deprecated behavior", () => {
     });
   });
 });
+
+describe("uses `dns.promises` implementations for `util.promisify` factory", () => {
+  it.each([
+    "lookup",
+    "lookupService",
+    "resolve",
+    "reverse",
+    "resolve4",
+    "resolve6",
+    "resolveAny",
+    "resolveCname",
+    "resolveCaa",
+    "resolveMx",
+    "resolveNs",
+    "resolvePtr",
+    "resolveSoa",
+    "resolveSrv",
+    "resolveTxt",
+    "resolveNaptr",
+  ])("%s", method => {
+    expect(dns[method][util.promisify.custom]).toBe(dns_promises[method]);
+    expect(dns.promises[method]).toBe(dns_promises[method]);
+  });
+
+  it("util.promisify(dns.lookup) acts like dns.promises.lookup", async () => {
+    expect(await util.promisify(dns.lookup)("example.com")).toEqual(await dns.promises.lookup("example.com"));
+  });
+});
diff --git a/test/js/node/util/util-promisify.test.js b/test/js/node/util/util-promisify.test.js
index 518e8b7ad..556659619 100644
--- a/test/js/node/util/util-promisify.test.js
+++ b/test/js/node/util/util-promisify.test.js
@@ -88,7 +88,6 @@ describe("util.promisify", () => {
 
       function promisifiedFn() {}
 
-      // TODO: register shared symbol promisify.custom
       // util.promisify.custom is a shared symbol which can be accessed
       // as `Symbol.for("nodejs.util.promisify.custom")`.
       const kCustomPromisifiedSymbol = Symbol.for("nodejs.util.promisify.custom");