fix: assign properties of mutations in withMutation

libs/ngrx-toolkit/src/lib/with-mutations.spec.ts

@@ -116,6 +116,31 @@ function createTestSetup(flatteningOperator = concatOp) {
 }
 
 describe('withMutations with rxMutation', () => {
+  // fix: assign properties of mutations in withMutation https://github.com/angular-architects/ngrx-toolkit/pull/288
+  it("does not lose the runtime properties of a mutation's direct reference when assigning it to a component field", fakeAsync(() => {
+    const testSetup = createTestSetup();
+    const store = testSetup.store;
+
+    // Simulates `readonly myMutation = this.store.increment` in a component.
+    const myMutation = store.increment;
+
+    expect(myMutation.status()).toEqual('idle');
+    expect(typeof myMutation.isPending).toEqual('function');
+    expect(myMutation.isPending()).toEqual(false);
+
+    myMutation(2);
+    expect(myMutation.status()).toEqual('pending');
+    expect(myMutation.isPending()).toEqual(true);
+
+    tick(2000);
+
+    expect(myMutation.status()).toEqual('success');
+    expect(myMutation.isPending()).toEqual(false);
+    expect(myMutation.error()).toEqual(undefined);
+
+    expect(store.counter()).toEqual(7);
+  }));
+
   it('should update the state', fakeAsync(() => {
     const testSetup = createTestSetup();
     const store = testSetup.store;

libs/ngrx-toolkit/src/lib/with-mutations.ts

@@ -118,14 +118,18 @@ function createMutationsFeature<Result extends MutationsDictionary>(
       keys.reduce(
         (acc, key) => ({
           ...acc,
-          [key]: async (params: never) => {
+          [key]: (() => {
             const mutation = mutations[key];
             if (!mutation) {
               throw new Error(`Mutation ${key} not found`);
             }
-            const result = await mutation(params);
-            return result;
-          },
+
+            return Object.assign(async (params: never) => {
+              const result = await mutation(params);
+
+              return result;
+            }, mutation);
+          })(),
         }),
         {} as MethodsDictionary,
       ),