fix(store): don't call the projector function if there are no selecto…

…rs and props (#1515)

Closes #1501

modules/store/spec/selector.spec.ts

@@ -143,6 +143,17 @@ describe('Selectors', () => {
       });
     });
 
+    it('should not short circuit to the projector fn if there are no selectors and props', () => {
+      const projectFn = jasmine.createSpy('projectionFn');
+      const state = { counter: {} };
+
+      const selector = (createSelector(projectFn) as any)(state);
+
+      // the projector still fires but without arguments,
+      // this because there are no selectors and props
+      expect(projectFn).toHaveBeenCalledWith();
+    });
+
     it('should be possible to test a projector fn independent from the selectors it is composed of', () => {
       const projectFn = jasmine.createSpy('projectionFn');
       const selector = createSelector(

modules/store/src/selector.ts

@@ -551,7 +551,7 @@ export function createSelectorFactory(
     const memoizedState = defaultMemoize(function(state: any, props: any) {
       // createSelector works directly on state
       // e.g. createSelector((state, props) => ...)
-      if (selectors.length === 0) {
+      if (selectors.length === 0 && props !== undefined) {
         return projector.apply(null, [state, props]);
       }