fix(core): move reload method from Resource to WritableResource (#61441)

Now only mutable resources can be reloaded.

PR Close #61441

goldens/public-api/core/index.api.md

@@ -1610,7 +1610,6 @@ export interface Resource<T> {
     readonly error: Signal<unknown>;
     hasValue(): this is Resource<Exclude<T, undefined>>;
     readonly isLoading: Signal<boolean>;
-    reload(): boolean;
     readonly status: Signal<ResourceStatus>;
     readonly value: Signal<T>;
 }
@@ -2022,6 +2021,7 @@ export interface WritableResource<T> extends Resource<T> {
     asReadonly(): Resource<T>;
     // (undocumented)
     hasValue(): this is WritableResource<Exclude<T, undefined>>;
+    reload(): boolean;
     set(value: T): void;
     update(updater: (value: T) => T): void;
     // (undocumented)

packages/common/http/test/resource_spec.ts

@@ -289,4 +289,18 @@ describe('httpResource', () => {
     await TestBed.inject(ApplicationRef).whenStable();
     expect(res.value()).toBe(buffer);
   });
+
+  it('should send request on reload', async () => {
+    const backend = TestBed.inject(HttpTestingController);
+    const res = httpResource(() => '/data', {injector: TestBed.inject(Injector)});
+    TestBed.tick();
+    let req = backend.expectOne('/data');
+    req.flush([]);
+    await TestBed.inject(ApplicationRef).whenStable();
+
+    res.reload();
+    TestBed.tick();
+    req = backend.expectOne('/data');
+    req.flush([]);
+  });
 });

packages/core/src/resource/api.ts

@@ -72,16 +72,6 @@ export interface Resource<T> {
    * This function is reactive.
    */
   hasValue(): this is Resource<Exclude<T, undefined>>;
-
-  /**
-   * Instructs the resource to re-load any asynchronous dependency it may have.
-   *
-   * Note that the resource will not enter its reloading state until the actual backend request is
-   * made.
-   *
-   * @returns true if a reload was initiated, false if a reload was unnecessary or unsupported
-   */
-  reload(): boolean;
 }
 
 /**
@@ -105,6 +95,16 @@ export interface WritableResource<T> extends Resource<T> {
    */
   update(updater: (value: T) => T): void;
   asReadonly(): Resource<T>;
+
+  /**
+   * Instructs the resource to re-load any asynchronous dependency it may have.
+   *
+   * Note that the resource will not enter its reloading state until the actual backend request is
+   * made.
+   *
+   * @returns true if a reload was initiated, false if a reload was unnecessary or unsupported
+   */
+  reload(): boolean;
 }
 
 /**