Remove status from favorites list when unfavorited (#4597)

app/javascript/mastodon/reducers/status_lists.js

@@ -3,7 +3,10 @@ import {
   FAVOURITED_STATUSES_EXPAND_SUCCESS,
 } from '../actions/favourites';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
-import { FAVOURITE_SUCCESS } from '../actions/interactions';
+import {
+  FAVOURITE_SUCCESS,
+  UNFAVOURITE_SUCCESS,
+} from '../actions/interactions';
 
 const initialState = ImmutableMap({
   favourites: ImmutableMap({
@@ -34,6 +37,12 @@ const prependOneToList = (state, listType, status) => {
   }));
 };
 
+const removeOneFromList = (state, listType, status) => {
+  return state.update(listType, listMap => listMap.withMutations(map => {
+    map.set('items', map.get('items').filter(item => item !== status.get('id')));
+  }));
+};
+
 export default function statusLists(state = initialState, action) {
   switch(action.type) {
   case FAVOURITED_STATUSES_FETCH_SUCCESS:
@@ -42,6 +51,8 @@ export default function statusLists(state = initialState, action) {
     return appendToList(state, 'favourites', action.statuses, action.next);
   case FAVOURITE_SUCCESS:
     return prependOneToList(state, 'favourites', action.status);
+  case UNFAVOURITE_SUCCESS:
+    return removeOneFromList(state, 'favourites', action.status);
   default:
     return state;
   }