From 8e9d3f94ac1cbcefe989115266026f5fd3e0a947 Mon Sep 17 00:00:00 2001
From: kaustubhOG <kaustubh.devlop@gmail.com>
Date: Wed, 1 Jul 2026 09:37:18 +0530
Subject: [PATCH] feat(wintertc): migrate queueMicrotask from boa_runtime

---
 core/wintertc/src/microtask/mod.rs   | 40 ++++++++++++++-------
 core/wintertc/src/microtask/tests.rs | 52 ++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 12 deletions(-)
 create mode 100644 core/wintertc/src/microtask/tests.rs

diff --git a/core/wintertc/src/microtask/mod.rs b/core/wintertc/src/microtask/mod.rs
index bae48303b4e..e1a40c7a226 100644
--- a/core/wintertc/src/microtask/mod.rs
+++ b/core/wintertc/src/microtask/mod.rs
@@ -5,19 +5,35 @@
 //! # TC55 Status
 //!
 //! `queueMicrotask` is required in the `WinterTC` TC55 Minimum Common Web API.
-//!
-//! # TODO
-//!
-//! - Migrate `queueMicrotask` from `boa_runtime::microtask`.
+use boa_engine::realm::Realm;
+use boa_engine::{Context, JsResult, boa_module};
+
+#[cfg(test)]
+mod tests;
+
+/// JavaScript module containing the `queueMicrotask` function.
+#[boa_module]
+pub mod js_module {
+    use boa_engine::job::{Job, PromiseJob};
+    use boa_engine::object::builtins::JsFunction;
+    use boa_engine::{Context, JsValue};
 
-/// Register `queueMicrotask` into the given context.
+    /// The [`queueMicrotask()`][mdn] method of the `Window` interface queues a
+    /// microtask to be executed at a safe time prior to control returning to
+    /// the browser's event loop.
+    ///
+    /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/API/Window/queueMicrotask
+    pub fn queue_microtask(callback: JsFunction, context: &mut Context) {
+        context.enqueue_job(Job::from(PromiseJob::new(move |context| {
+            callback.call(&JsValue::undefined(), &[], context)
+        })));
+    }
+}
+
+/// Register the `queueMicrotask` function to the realm or context.
 ///
 /// # Errors
-///
-/// Returns a [`boa_engine::JsError`] if registration fails.
-pub fn register(
-    _realm: Option<boa_engine::realm::Realm>,
-    _ctx: &mut boa_engine::Context,
-) -> boa_engine::JsResult<()> {
-    Ok(())
+/// Returns an error if the microtask extension cannot be registered.
+pub fn register(realm: Option<Realm>, context: &mut Context) -> JsResult<()> {
+    js_module::boa_register(realm, context)
 }
diff --git a/core/wintertc/src/microtask/tests.rs b/core/wintertc/src/microtask/tests.rs
new file mode 100644
index 00000000000..e8ee935cbda
--- /dev/null
+++ b/core/wintertc/src/microtask/tests.rs
@@ -0,0 +1,52 @@
+use crate::test::{TestAction, run_test_actions_with};
+use boa_engine::Context;
+use indoc::indoc;
+
+#[test]
+fn queue_microtask() {
+    let context = &mut Context::default();
+    crate::microtask::register(None, context).unwrap();
+
+    run_test_actions_with(
+        [
+            // Queue a nested set of microtasks, recording execution order into
+            // a global array. Microtasks run in FIFO order after the current
+            // synchronous task completes, and microtasks queued from within a
+            // microtask are appended to the same queue.
+            TestAction::run(indoc! {r#"
+                globalThis.order = [];
+                order.push(1);
+                queueMicrotask(() => order.push(2));
+                order.push(3);
+                queueMicrotask(() => {
+                    order.push(4);
+                    queueMicrotask(() => {
+                        order.push(5);
+                        queueMicrotask(() => order.push(6));
+                        order.push(7);
+                    });
+                    order.push(8);
+                });
+                order.push(9);
+            "#}),
+            // Drain the microtask (job) queue.
+            TestAction::inspect_context(|context| {
+                context.run_jobs().unwrap();
+            }),
+            // The synchronous pushes (1, 3, 9) run first, then the microtasks
+            // in the order they were queued and re-queued.
+            TestAction::run(indoc! {r#"
+                var expected = [1, 3, 9, 2, 4, 8, 5, 7, 6];
+                if (order.length !== expected.length) {
+                    throw new Error("wrong length: [" + order + "]");
+                }
+                for (var i = 0; i < expected.length; i++) {
+                    if (order[i] !== expected[i]) {
+                        throw new Error("wrong order at " + i + ": [" + order + "]");
+                    }
+                }
+            "#}),
+        ],
+        context,
+    );
+}