feat: polyfill Promise.withResolvers (#368)

rs-lib/src/polyfills/mod.rs

@@ -19,6 +19,7 @@ mod array_from_async;
 mod error_cause;
 mod import_meta;
 mod object_has_own;
+mod promise_with_resolvers;
 mod string_replace_all;
 
 pub trait Polyfill {
@@ -109,6 +110,7 @@ fn all_polyfills() -> Vec<Box<dyn Polyfill>> {
     Box::new(array_find_last::ArrayFindLastPolyfill),
     Box::new(array_from_async::ArrayFromAsyncPolyfill),
     Box::new(import_meta::ImportMetaPolyfill),
+    Box::new(promise_with_resolvers::PromiseWithResolversPolyfill),
   ]
 }
 

rs-lib/src/polyfills/promise_with_resolvers.rs

@@ -0,0 +1,62 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+use deno_ast::view::Node;
+
+use super::Polyfill;
+use super::PolyfillVisitContext;
+use crate::ScriptTarget;
+
+pub struct PromiseWithResolversPolyfill;
+
+impl Polyfill for PromiseWithResolversPolyfill {
+  fn use_for_target(&self, _target: ScriptTarget) -> bool {
+    // (target as u32) < (ScriptTarget::ES2021 as u32)
+    true // just always use it for the time being
+  }
+
+  fn visit_node(&self, node: Node, context: &PolyfillVisitContext) -> bool {
+    context.has_global_property_access(node, "Promise", "withResolvers")
+  }
+
+  fn get_file_text(&self) -> &'static str {
+    include_str!("./scripts/es2021.promise-withResolvers.ts")
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use crate::polyfills::PolyfillTester;
+
+  #[test]
+  pub fn finds_when_matches() {
+    let tester =
+      PolyfillTester::new(Box::new(|| Box::new(PromiseWithResolversPolyfill)));
+    assert_eq!(tester.matches("Promise.withResolvers"), true);
+    assert_eq!(
+      tester.matches("class Promise {} Promise.withResolvers"),
+      false
+    );
+    assert_eq!(tester.matches("Other.withResolvers"), false);
+    assert_eq!(tester.matches("Promise.withResolvers2"), false);
+    assert_eq!(tester.matches("const { withResolvers } = Promise;"), true);
+    assert_eq!(
+      tester.matches("const { withResolvers: test } = Promise;"),
+      true
+    );
+    assert_eq!(
+      tester.matches("const { \"withResolvers\": test } = Promise;"),
+      true
+    );
+    assert_eq!(tester.matches("const { withResolvers } = other;"), false);
+    assert_eq!(
+      tester.matches("class Promise {} const { withResolvers } = Promise;"),
+      false
+    );
+    assert_eq!(tester.matches("const { ...rest } = Promise;"), true); // unknown, so true
+    assert_eq!(
+      tester.matches("const { [computed]: test } = Promise;"),
+      true
+    ); // unknown, so true
+  }
+}

rs-lib/src/polyfills/scripts/es2021.promise-withResolvers.ts

@@ -0,0 +1,22 @@
+declare global {
+  // https://github.com/denoland/deno/blob/0bfa0cc0276e94f1a308aaad5f925eaacb6e3db2/cli/tsc/dts/lib.es2021.promise.d.ts#L53
+  interface PromiseConstructor {
+    /**
+     * Creates a Promise that can be resolved or rejected using provided functions.
+     * @returns An object containing `promise` promise object, `resolve` and `reject` functions.
+     */
+    withResolvers<T>(): { promise: Promise<T>, resolve: (value: T | PromiseLike<T>) => void, reject: (reason?: any) => void };
+  }
+}
+
+// https://github.com/tc39/proposal-promise-with-resolvers/blob/3a78801e073e99217dbeb2c43ba7212f3bdc8b83/polyfills.js#L1C1-L9C2
+if (Promise.withResolvers === undefined) {
+  Promise.withResolvers = () => {
+    const out: any = {};
+    out.promise = new Promise((resolve_, reject_) => {
+      out.resolve = resolve_;
+      out.reject = reject_;
+    });
+    return out;
+  };
+}

tests/polyfill_project/mod.test.ts

@@ -1,9 +1,16 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
-import { hasOwn } from "./mod.ts";
 import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";
+import { hasOwn, withResolvers } from "./mod.ts";
 
 Deno.test("should test the polyfill", () => {
   assertEquals(hasOwn({}), false);
   assertEquals(hasOwn({ prop: 5 }), true);
 });
+
+Deno.test("with resolvers", async () => {
+  const { promise, resolve } = withResolvers<number>();
+  setTimeout(() => resolve(5), 10);
+  const value = await promise;
+  assertEquals(value, 5);
+});

tests/polyfill_project/mod.ts

@@ -7,3 +7,7 @@ export function hasOwn(a: { prop?: number }) {
     err.cause = new Error("test");
   }
 }
+
+export function withResolvers<T>() {
+  return Promise.withResolvers<T>();
+}