From 6f9ae267456dff4fddea9e47407588584277f951 Mon Sep 17 00:00:00 2001
From: Leon Senft <leonsenft@users.noreply.github.com>
Date: Tue, 10 Dec 2024 13:39:21 -0800
Subject: [PATCH] Test that `computed` can recover from a throwing `equal`
 implementation

---
 packages/core/test/signals/computed_spec.ts | 27 ++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/packages/core/test/signals/computed_spec.ts b/packages/core/test/signals/computed_spec.ts
index 27b954b7887763..24243bb9d1546d 100644
--- a/packages/core/test/signals/computed_spec.ts
+++ b/packages/core/test/signals/computed_spec.ts
@@ -7,7 +7,7 @@
  */
 
 import {computed, signal} from '@angular/core';
-import {createWatch, ReactiveNode, SIGNAL} from '@angular/core/primitives/signals';
+import {createWatch, ReactiveNode, SIGNAL, defaultEquals} from '@angular/core/primitives/signals';
 
 describe('computed', () => {
   it('should create computed', () => {
@@ -291,5 +291,30 @@ describe('computed', () => {
       // context either.
       expect(outerRunCount).toBe(1);
     });
+
+    it('should recover from exception', () => {
+      let shouldThrow = true;
+      const source = signal(0);
+      const derived = computed(source, {
+        equal: (a, b) => {
+          if (shouldThrow) {
+            throw new Error('equal');
+          }
+          return defaultEquals(a, b);
+        },
+      });
+
+      // Initial read doesn't throw because it doesn't call `equal`.
+      expect(derived()).toBe(0);
+
+      // Update `source` to begin throwing.
+      source.set(1);
+      expect(() => derived()).toThrowError('equal');
+
+      // Stop throwing and update `source` to cause `derived` to recompute.
+      shouldThrow = false;
+      source.set(2);
+      expect(derived()).toBe(2);
+    });
   });
 });