From 1f07f71283c2c0bfa35244facab03cf11a2d9b46 Mon Sep 17 00:00:00 2001
From: Kristiyan Kostadinov <crisbeto@abv.bg>
Date: Tue, 28 Jan 2025 21:54:21 +0100
Subject: [PATCH] fix(core): cancel in-progress request when same value is
 assigned

Fixes that `resource` wasn't cancelling its in-progress request if the same value as the current one is assigned.

Fixes #59272.
---
 packages/core/src/resource/resource.ts       |  6 ++-
 packages/core/test/resource/resource_spec.ts | 53 ++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/resource/resource.ts b/packages/core/src/resource/resource.ts
index 7392e511bf19..18ba9d0f7d2d 100644
--- a/packages/core/src/resource/resource.ts
+++ b/packages/core/src/resource/resource.ts
@@ -221,7 +221,11 @@ class ResourceImpl<T, R> extends BaseWritableResource<T> implements ResourceRef<
     }
 
     const current = untracked(this.value);
-    if (this.equal ? this.equal(current, value) : current === value) {
+
+    if (
+      untracked(this.status) === ResourceStatus.Local &&
+      (this.equal ? this.equal(current, value) : current === value)
+    ) {
       return;
     }
 
diff --git a/packages/core/test/resource/resource_spec.ts b/packages/core/test/resource/resource_spec.ts
index aac793b9eff8..ef04b4d92385 100644
--- a/packages/core/test/resource/resource_spec.ts
+++ b/packages/core/test/resource/resource_spec.ts
@@ -622,6 +622,59 @@ describe('resource', () => {
     stream.set({error: 'fail'});
     expect(res.value()).toBe(undefined);
   });
+
+  it('should interrupt pending request if the same value is set', async () => {
+    const counter = signal(0);
+    const backend = new MockEchoBackend<{counter: number} | null>();
+    const aborted: ({counter: number} | null)[] = [];
+    const echoResource = resource<{counter: number} | null, {counter: number} | null>({
+      request: () => ({counter: counter()}),
+      loader: ({request, abortSignal}) => {
+        abortSignal.addEventListener('abort', () => backend.abort(request));
+        return backend.fetch(request).catch((reason) => {
+          if (reason === 'aborted') {
+            aborted.push(request);
+          }
+          throw new Error(reason);
+        });
+      },
+      injector: TestBed.inject(Injector),
+    });
+
+    // Start the initial load.
+    TestBed.flushEffects();
+    await Promise.resolve();
+    expect(echoResource.status()).toBe(ResourceStatus.Loading);
+    expect(echoResource.value()).toBe(undefined);
+    expect(echoResource.error()).toBe(undefined);
+    expect(aborted).toEqual([]);
+
+    // Interrupt by setting a value before the request has resolved.
+    echoResource.set(null);
+    TestBed.flushEffects();
+    await backend.flush();
+    expect(echoResource.status()).toBe(ResourceStatus.Local);
+    expect(echoResource.value()).toBe(null);
+    expect(echoResource.error()).toBe(undefined);
+    expect(aborted).toEqual([{counter: 0}]);
+
+    // Reload the resource to trigger another request.
+    echoResource.reload();
+    TestBed.flushEffects();
+    await Promise.resolve();
+    expect(echoResource.status()).toBe(ResourceStatus.Reloading);
+    expect(echoResource.value()).toBe(null);
+    expect(echoResource.error()).toBe(undefined);
+    expect(aborted).toEqual([{counter: 0}]);
+
+    // Interrupt the reload with the same value as before.
+    echoResource.set(null);
+    await backend.flush();
+    expect(echoResource.status()).toBe(ResourceStatus.Local);
+    expect(echoResource.value()).toBe(null);
+    expect(echoResource.error()).toBe(undefined);
+    expect(aborted).toEqual([{counter: 0}, {counter: 0}]);
+  });
 });
 
 function flushMicrotasks(): Promise<void> {