fix(component-store): fix memoization not working when passing select…

…ors directly to select

This makes selectors created with `createSelector` usable with `ComponentStore.select`
which looks like it should work, but would previously result in the selector getting recomputed each time.

When select method is called with a single argument, the projector function was being passed directly to `map`,
which invokes its callback with an extra `index` argument. Because the value of index is always different,
the memoized selector would get invalidated even if the actual state remained exactly the same.

modules/component-store/spec/component-store.spec.ts

@@ -23,6 +23,7 @@ import {
   delay,
   concatMap,
 } from 'rxjs/operators';
+import { createSelector } from '@ngrx/store';
 
 describe('Component Store', () => {
   describe('initialization', () => {
@@ -895,6 +896,23 @@ describe('Component Store', () => {
 
       componentStore.ngOnDestroy();
     });
+
+    it('supports memoization with createSelector', () => {
+      const projectorCallback = jest.fn((str: string) => str);
+      const memoizedSelector = createSelector(
+        (s: State) => s.value,
+        projectorCallback
+      );
+      const selector = componentStore.select(memoizedSelector);
+
+      // first call to memoizedSelector
+      const subscription = selector.subscribe();
+      // second call to memoizedSelector with the same value
+      componentStore.setState(INIT_STATE);
+
+      subscription.unsubscribe();
+      expect(projectorCallback).toHaveBeenCalledTimes(1);
+    });
   });
 
   describe('selector with debounce', () => {

modules/component-store/src/component-store.ts

@@ -244,7 +244,7 @@ export class ComponentStore<T extends object> implements OnDestroy {
     if (observables.length === 0) {
       observable$ = this.stateSubject$.pipe(
         config.debounce ? debounceSync() : (source$) => source$,
-        map(projector)
+        map((arg) => projector(arg))
       );
     } else {
       // If there are multiple arguments, then we're aggregating selectors, so we need