fix(ext/node): Add Immediate class to mirror NodeJS.Immediate (#22808)

Fixes #21660

Adds a basic `Immediate` class to mirror `NodeJS.Immediate`, and changes
`setImmediate` and `clearImmediate` to return and accept (respectively)
`Immediate` objects.

Note that for now {ref,unref,hasRef} are effectively stubs, as deno_core
doesn't really natively support immediates (they're currently modeled as
timers with delay of 0). Eventually we probably want to actually
implement these properly.

1 files changed, 14 insertions, 4 deletions

diff --git a/tests/unit_node/timers_test.ts b/tests/unit_node/timers_test.ts
index 9ce015d23..c0b49c998 100644
--- a/tests/unit_node/timers_test.ts
+++ b/tests/unit_node/timers_test.ts
@@ -33,13 +33,13 @@ Deno.test("[node/timers setInterval]", () => {
 Deno.test("[node/timers setImmediate]", () => {
   {
     const { clearImmediate, setImmediate } = timers;
-    const id = setImmediate(() => {});
-    clearImmediate(id);
+    const imm = setImmediate(() => {});
+    clearImmediate(imm);
   }
 
   {
-    const id = timers.setImmediate(() => {});
-    timers.clearImmediate(id);
+    const imm = timers.setImmediate(() => {});
+    timers.clearImmediate(imm);
   }
 });
 
@@ -60,3 +60,13 @@ Deno.test("[node/timers refresh cancelled timer]", () => {
   clearTimeout(p);
   p.refresh();
 });
+
+Deno.test("[node/timers setImmediate returns Immediate object]", () => {
+  const { clearImmediate, setImmediate } = timers;
+
+  const imm = setImmediate(() => {});
+  imm.unref();
+  imm.ref();
+  imm.hasRef();
+  clearImmediate(imm);
+});