feat(store): allow multiple on handlers for the same action in create…

…Reducer(#2103)

Closes #1956

modules/store/spec/reducer_creator.spec.ts

@@ -86,6 +86,23 @@ import {on} from './modules/store/src/reducer_creator';
  state = fooBarReducer(state, bar({ bar: 54 }));
  expect(state).toEqual(['[foobar] FOO', '[foobar] BAR']);
  });
+
+ it('should support "on"s to have identical action types', () => {
+ const increase = createAction('[COUNTER] increase');
+
+ const counterReducer = createReducer(
+ 0,
+ on(increase, state => state + 1),
+ on(increase, state => state + 1)
+ );
+
+ expect(typeof counterReducer).toEqual('function');
+
+ let state = 5;
+
+ state = counterReducer(state, increase());
+ expect(state).toEqual(7);
+ });
  });
  });
 });

modules/store/src/reducer_creator.ts

@@ -232,7 +232,14 @@ export function createReducer<S, A extends Action = Action>(
  const map = new Map<string, ActionReducer<S, A>>();
  for (let on of ons) {
  for (let type of on.types) {
- map.set(type, on.reducer);
+ if (map.has(type)) {
+ const existingReducer = map.get(type) as ActionReducer<S, A>;
+ const newReducer: ActionReducer<S, A> = (state, action) =>
+ on.reducer(existingReducer(state, action), action);
+ map.set(type, newReducer);
+ } else {
+ map.set(type, on.reducer);
+ }
  }
  }