3 files changed, 129 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);
     }
diff --git a/cli/tests/unit/os_test.ts b/cli/tests/unit/os_test.ts
new file mode 100644
index 000000000..af6ef219a
--- /dev/null
+++ b/cli/tests/unit/os_test.ts
@@ -0,0 +1,94 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals, assertThrows } from "../../testing/asserts.ts";
+
+Deno.test("Deno.exitCode getter and setter", () => {
+  // Initial value is 0
+  assertEquals(Deno.exitCode, 0);
+
+  // Set a new value
+  Deno.exitCode = 5;
+  assertEquals(Deno.exitCode, 5);
+
+  // Reset to initial value
+  Deno.exitCode = 0;
+  assertEquals(Deno.exitCode, 0);
+});
+
+Deno.test("Setting Deno.exitCode to NaN throws TypeError", () => {
+  // @ts-expect-error;
+  Deno.exitCode = "123";
+  assertEquals(Deno.exitCode, 123);
+
+  // Reset
+  Deno.exitCode = 0;
+  assertEquals(Deno.exitCode, 0);
+
+  // Throws on non-number values
+  assertThrows(
+    () => {
+      // @ts-expect-error Testing for runtime error
+      Deno.exitCode = "not a number";
+    },
+    TypeError,
+    "Exit code must be a number.",
+  );
+});
+
+Deno.test("Setting Deno.exitCode does not cause an immediate exit", () => {
+  let exited = false;
+  const originalExit = Deno.exit;
+
+  // @ts-expect-error; read-only
+  Deno.exit = () => {
+    exited = true;
+  };
+
+  Deno.exitCode = 1;
+  assertEquals(exited, false);
+
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Running Deno.exit(value) overrides Deno.exitCode", () => {
+  let args: unknown[] | undefined;
+
+  const originalExit = Deno.exit;
+  // @ts-expect-error; read-only
+  Deno.exit = (...x) => {
+    args = x;
+  };
+
+  Deno.exitCode = 42;
+  Deno.exit(0);
+
+  assertEquals(args, [0]);
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Running Deno.exit() uses Deno.exitCode as fallback", () => {
+  let args: unknown[] | undefined;
+
+  const originalExit = Deno.exit;
+  // @ts-expect-error; read-only
+  Deno.exit = (...x) => {
+    args = x;
+  };
+
+  Deno.exitCode = 42;
+  Deno.exit();
+
+  assertEquals(args, [42]);
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Retrieving the set exit code before process termination", () => {
+  Deno.exitCode = 42;
+  assertEquals(Deno.exitCode, 42);
+
+  // Reset to initial value
+  Deno.exitCode = 0;
+});
diff --git a/cli/tsc/dts/lib.deno.ns.d.ts b/cli/tsc/dts/lib.deno.ns.d.ts
index 76b59761c..cf8e4ba05 100644
--- a/cli/tsc/dts/lib.deno.ns.d.ts
+++ b/cli/tsc/dts/lib.deno.ns.d.ts
@@ -1466,6 +1466,23 @@ declare namespace Deno {
    */
   export function exit(code?: number): never;
 
+  /** The exit code for the Deno process.
+   *
+   * If no exit code has been supplied, then Deno will assume a return code of `0`.
+   *
+   * When setting an exit code value, a number or non-NaN string must be provided,
+   * otherwise a TypeError will be thrown.
+   *
+   * ```ts
+   * console.log(Deno.exitCode); //-> 0
+   * Deno.exitCode = 1;
+   * console.log(Deno.exitCode); //-> 1
+   * ```
+   *
+   * @category Runtime
+   */
+  export var exitCode: number;
+
   /** An interface containing methods to interact with the process environment
    * variables.
    *