recover with identity if reducer throw error, so other reducer can still work without block by it

Author: jcouyang

ROADMAP.org

@@ -1,10 +1,11 @@
-* RoadMap [0%]
+* RoadMap [50%]
 
-- [ ] modular, extra engine.
-- [ ] time travel
-  - [ ] inspect
-  - [ ] history.back()
+- [X] modular, extra engine.
+- [X] time travel
+  - [X] inspect
+  - [X] history.back()
 - [ ] unsubscribe when component unmount
-- [ ] todo example
+- [X] todo example
 - [ ] router example
-- [ ]
+- [ ] typescript typedef
+- [ ] flow type

lib/__tests__/react-most-test.jsx

@@ -250,4 +250,37 @@ describe('react-most', () => {
         .then(state=>expect(state.count).toEqual(6))
     })
   })
+
+  describe('convension default to `action` field in sinks', ()=>{
+    const Counter = connect(intent$=>{
+      return {
+        sink$: intent$.map(intent=>{
+          switch(intent.type) {
+            case 'exception':
+              throw new Error('exception in reducer')
+            default:
+              return state=>state
+          }
+        }),
+        actions: {
+          throwExeption: ()=>({type: 'exception'})
+        },
+      }
+    })(CounterView)
+
+    it('should recover to identity stream and log exception', ()=>{
+      spyOn(console, 'error')
+      let counterWrapper = TestUtils.renderIntoDocument(
+        <Most >
+          <Counter history={true} />
+        </Most>
+      )
+      let counter = TestUtils.findRenderedComponentWithType(counterWrapper, Counter)
+      return do$([
+        counter.actions.throwExeption,
+      ]).then(()=>{
+        expect(console.error).toHaveBeenCalled()
+      })
+    })
+  })
 })

lib/engine/most.js

@@ -1,4 +1,4 @@
-import {from,mergeArray} from 'most'
+import {from, of, mergeArray} from 'most'
 import {async as subject} from 'most-subject'
 export default function Engine() {
   const intentStream = subject(),
@@ -9,7 +9,12 @@ export default function Engine() {
   travelStream.send = travelStream.next.bind(travelStream);
 
   function flatObserve(actionsSinks, f){
-    return mergeArray(actionsSinks).observe(f);
+    return mergeArray(actionsSinks)
+      .recoverWith(e => {
+        console.error('There is Error in your reducer:',e, e.stack)
+        return of(x=>x)
+      })
+      .observe(f);
   }
   historyStream.travel = travelStream;
   return {intentStream, flatObserve, historyStream}