6 files changed, 87 insertions, 2 deletions
diff --git a/test/js/web/timers/setTimeout-unref-fixture-2.js b/test/js/web/timers/setTimeout-unref-fixture-2.js
new file mode 100644
index 000000000..6a78f13cd
--- /dev/null
+++ b/test/js/web/timers/setTimeout-unref-fixture-2.js
@@ -0,0 +1,9 @@
+setTimeout(() => {
+  console.log("TEST FAILED!");
+}, 100)
+  .ref()
+  .unref();
+
+setTimeout(() => {
+  // this one should always run
+}, 1);
diff --git a/test/js/web/timers/setTimeout-unref-fixture-3.js b/test/js/web/timers/setTimeout-unref-fixture-3.js
new file mode 100644
index 000000000..41808f5fc
--- /dev/null
+++ b/test/js/web/timers/setTimeout-unref-fixture-3.js
@@ -0,0 +1,7 @@
+setTimeout(() => {
+  setTimeout(() => {}, 999_999);
+}, 100).unref();
+
+setTimeout(() => {
+  // this one should always run
+}, 1);
diff --git a/test/js/web/timers/setTimeout-unref-fixture-4.js b/test/js/web/timers/setTimeout-unref-fixture-4.js
new file mode 100644
index 000000000..9968f3b36
--- /dev/null
+++ b/test/js/web/timers/setTimeout-unref-fixture-4.js
@@ -0,0 +1,5 @@
+setTimeout(() => {
+  console.log("TEST PASSED!");
+}, 1)
+  .unref()
+  .ref();
diff --git a/test/js/web/timers/setTimeout-unref-fixture-5.js b/test/js/web/timers/setTimeout-unref-fixture-5.js
new file mode 100644
index 000000000..e5caa1be4
--- /dev/null
+++ b/test/js/web/timers/setTimeout-unref-fixture-5.js
@@ -0,0 +1,5 @@
+setTimeout(() => {
+  console.log("TEST FAILED!");
+}, 100)
+  .ref()
+  .unref();
diff --git a/test/js/web/timers/setTimeout-unref-fixture.js b/test/js/web/timers/setTimeout-unref-fixture.js
new file mode 100644
index 000000000..97a0f78a2
--- /dev/null
+++ b/test/js/web/timers/setTimeout-unref-fixture.js
@@ -0,0 +1,12 @@
+const timer = setTimeout(() => {}, 999_999_999);
+if (timer.unref() !== timer) throw new Error("Expected timer.unref() === timer");
+
+var ranCount = 0;
+const going2Refresh = setTimeout(() => {
+  if (ranCount < 1) going2Refresh.refresh();
+  ranCount++;
+
+  if (ranCount === 2) {
+    console.log("SUCCESS");
+  }
+}, 1);
diff --git a/test/js/web/timers/setTimeout.test.js b/test/js/web/timers/setTimeout.test.js
index dbe89dea8..eef6bbae0 100644
--- a/test/js/web/timers/setTimeout.test.js
+++ b/test/js/web/timers/setTimeout.test.js
@@ -1,5 +1,7 @@
+import { spawnSync } from "bun";
 import { it, expect } from "bun:test";
-
+import { bunEnv, bunExe } from "harness";
+import path from "node:path";
 it("setTimeout", async () => {
   var lastID = -1;
   const result = await new Promise((resolve, reject) => {
@@ -172,11 +174,56 @@ it.skip("order of setTimeouts", done => {
   Promise.resolve().then(maybeDone(() => nums.push(1)));
 });
 
+it("setTimeout -> refresh", () => {
+  const { exitCode, stdout } = spawnSync({
+    cmd: [bunExe(), path.join(import.meta.dir, "setTimeout-unref-fixture.js")],
+    env: bunEnv,
+  });
+  expect(exitCode).toBe(0);
+  expect(stdout.toString()).toBe("SUCCESS\n");
+});
+
+it("setTimeout -> unref -> ref works", () => {
+  const { exitCode, stdout } = spawnSync({
+    cmd: [bunExe(), path.join(import.meta.dir, "setTimeout-unref-fixture-4.js")],
+    env: bunEnv,
+  });
+  expect(exitCode).toBe(0);
+  expect(stdout.toString()).toBe("TEST PASSED!\n");
+});
+
+it("setTimeout -> ref -> unref works, even if there is another timer", () => {
+  const { exitCode, stdout } = spawnSync({
+    cmd: [bunExe(), path.join(import.meta.dir, "setTimeout-unref-fixture-2.js")],
+    env: bunEnv,
+  });
+  expect(exitCode).toBe(0);
+  expect(stdout.toString()).toBe("");
+});
+
+it("setTimeout -> ref -> unref works", () => {
+  const { exitCode, stdout } = spawnSync({
+    cmd: [bunExe(), path.join(import.meta.dir, "setTimeout-unref-fixture-5.js")],
+    env: bunEnv,
+  });
+  expect(exitCode).toBe(0);
+  expect(stdout.toString()).toBe("");
+});
+
+it("setTimeout -> unref doesn't keep event loop alive forever", () => {
+  const { exitCode, stdout } = spawnSync({
+    cmd: [bunExe(), path.join(import.meta.dir, "setTimeout-unref-fixture-3.js")],
+    env: bunEnv,
+  });
+  expect(exitCode).toBe(0);
+  expect(stdout.toString()).toBe("");
+});
+
 it("setTimeout should refresh N times", done => {
   let count = 0;
   let timer = setTimeout(() => {
     count++;
-    timer.refresh();
+    expect(timer.refresh()).toBe(timer);
   }, 50);
 
   setTimeout(() => {