feat: Add `Deno.exitCode` API (#23609)

This commits adds the ability to set a would-be exit code 
for the Deno process without forcing an immediate exit, 
through the new `Deno.exitCode` API.

- **Implements `Deno.exitCode` getter and setter**: Adds support for
setting
and retrieving a would-be exit code via `Deno.exitCode`.
This allows for asynchronous cleanup before process termination 
without immediately exiting.
- **Ensures type safety**: The setter for `Deno.exitCode` validates that
the provided value is a number, throwing a TypeError if not, to ensure
that
only valid exit codes are set.

Closes to #23605

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/cli/js/40_test.js b/cli/js/40_test.js
index 2877bfa9b..5a081e217 100644
--- a/cli/js/40_test.js
+++ b/cli/js/40_test.js
@@ -28,6 +28,10 @@ const {
 
 import { setExitHandler } from "ext:runtime/30_os.js";
 
+// Capture `Deno` global so that users deleting or mangling it, won't
+// have impact on our sanitizers.
+const DenoNs = globalThis.Deno;
+
 /**
  * @typedef {{
  *   id: number,
@@ -101,7 +105,20 @@ function assertExit(fn, isTest) {
 
     try {
       const innerResult = await fn(...new SafeArrayIterator(params));
-      if (innerResult) return innerResult;
+      const exitCode = DenoNs.exitCode;
+      if (exitCode !== 0) {
+        // Reset the code to allow other tests to run...
+        DenoNs.exitCode = 0;
+        // ...and fail the current test.
+        throw new Error(
+          `${
+            isTest ? "Test case" : "Bench"
+          } finished with exit code set to ${exitCode}.`,
+        );
+      }
+      if (innerResult) {
+        return innerResult;
+      }
     } finally {
       setExitHandler(null);
     }