Get devtools working

package.json

@@ -53,6 +53,7 @@
     "karma-webpack": "^1.7.0",
     "mocha": "^2.3.4",
     "redux": "^3.0.4",
+    "redux-devtools": "^2.1.5",
     "webpack": "^1.12.9"
   },
   "dependencies": {

src/index.js

@@ -55,12 +55,26 @@ function update(state=initialState, { type, payload }) {
 // Syncing
 
 function locationsAreEqual(a, b) {
-  return a.path === b.path && deepEqual(a.state, b.state);
+  return a != null && b != null && a.path === b.path && deepEqual(a.state, b.state);
 }
 
 function syncReduxAndRouter(history, store, selectRouterState = SELECT_STATE) {
   const getRouterState = () => selectRouterState(store.getState());
-  let lastChangeId = 0;
+
+  // Because we're not able to set the initial path in `initialState` we need a
+  // "hack" to get "Revert" in Redux DevTools to work. We solve this by keeping
+  // the first route so we can revert to this route when the initial state is
+  // replayed to reset the state. Basically, we treat the first route as our
+  // initial state.
+  let firstRoute = undefined;
+
+  // To properly handle store updates we need to track the last route. This
+  // route contains a `changeId` which is updated on every `pushPath` and
+  // `replacePath`. If this id changes we always trigger a history update.
+  // However, if the id does not change, we check if the location has changed,
+  // and if it is we trigger a history update. (If these are out of sync it's
+  // likely because of React DevTools.)
+  let lastRoute = undefined;
 
   if(!getRouterState()) {
     throw new Error(
@@ -75,6 +89,10 @@ function syncReduxAndRouter(history, store, selectRouterState = SELECT_STATE) {
       state: location.state
     };
 
+    if (firstRoute === undefined) {
+      firstRoute = route;
+    }
+
     // Avoid dispatching an action if the store is already up-to-date,
     // even if `history` wouldn't do anything if the location is the same
     if(locationsAreEqual(getRouterState(), route)) return;
@@ -87,14 +105,22 @@ function syncReduxAndRouter(history, store, selectRouterState = SELECT_STATE) {
   });
 
   const unsubscribeStore = store.subscribe(() => {
-    const routing = getRouterState();
+    let routing = getRouterState();
 
-    // Only update the router once per `pushPath` call. This is
-    // indicated by the `changeId` state; when that number changes, we
-    // should update the history.
-    if(lastChangeId === routing.changeId) return;
+    // Treat `firstRoute` as our `initialState`
+    if(routing === initialState) {
+      routing = firstRoute;
+    }
+
+    // Only trigger history update is this is a new change or the location
+    // has changed.
+    if(lastRoute !== undefined &&
+      lastRoute.changeId === routing.changeId &&
+      locationsAreEqual(lastRoute, routing)) {
+      return;
+    }
 
-    lastChangeId = routing.changeId;
+    lastRoute = routing;
 
     const method = routing.replace ? 'replaceState' : 'pushState';
 

test/createTests.js

@@ -1,6 +1,8 @@
 const expect = require('expect');
 const { pushPath, replacePath, UPDATE_PATH, routeReducer, syncReduxAndRouter } = require('../src/index');
-const { createStore, combineReducers } = require('redux');
+const { createStore, combineReducers, compose } = require('redux');
+const { devTools } = require('redux-devtools');
+const { ActionCreators } = require('redux-devtools/lib/devTools');
 
 function createSyncedHistoryAndStore(createHistory) {
   const store = createStore(combineReducers({
@@ -130,6 +132,77 @@ module.exports = function createTests(createHistory, name, reset = defaultReset)
       });
     });
 
+    describe('devtools', () => {
+      let history, store, devToolsStore, unsubscribe;
+
+      beforeEach(() => {
+        history = createHistory();
+        const finalCreateStore = compose(devTools())(createStore);
+        store = finalCreateStore(combineReducers({
+          routing: routeReducer
+        }));
+        devToolsStore = store.devToolsStore;
+
+        // Set initial URL before syncing
+        history.pushState(null, '/foo');
+
+        unsubscribe = syncReduxAndRouter(history, store);
+      });
+
+      afterEach(() => {
+        unsubscribe();
+      });
+
+      it('resets to the initial url', () => {
+        let lastPath;
+        const historyUnsubscribe = history.listen(location => {
+          lastPath = location.pathname;
+        });
+
+        history.pushState(null, '/bar');
+        store.dispatch(pushPath('/baz'));
+
+        devToolsStore.dispatch(ActionCreators.reset());
+
+        expect(store.getState().routing.path).toEqual('/foo');
+        expect(lastPath).toEqual('/foo');
+      });
+
+      it('handles toggle after store change', () => {
+        let lastPath;
+        const historyUnsubscribe = history.listen(location => {
+          lastPath = location.pathname;
+        });
+
+        // action 2
+        history.pushState(null, '/foo2');
+        // action 3
+        history.pushState(null, '/foo3');
+
+        devToolsStore.dispatch(ActionCreators.toggleAction(3));
+        expect(lastPath).toEqual('/foo2');
+
+        historyUnsubscribe();
+      });
+
+      it('handles toggle after store change', () => {
+        let lastPath;
+        const historyUnsubscribe = history.listen(location => {
+          lastPath = location.pathname;
+        });
+
+        // action 2
+        store.dispatch(pushPath('/foo2'));
+        // action 3
+        store.dispatch(pushPath('/foo3'));
+
+        devToolsStore.dispatch(ActionCreators.toggleAction(3));
+        expect(lastPath).toEqual('/foo2');
+
+        historyUnsubscribe();
+      });
+    });
+
     describe('syncReduxAndRouter', () => {
       let history, store, unsubscribe;