added support for watch as array and moved all the watch logic to seprate module.

src/index.js

@@ -6,6 +6,8 @@ import {
   silentGetLazy,
   silentSetLazy,
 } from './lazy'
+import { getWatchedGetter } from './watch'
+
 
 const prefix = '_async_computed$'
 const DidNotUpdate = typeof Symbol === 'function' ? Symbol('did-not-update') : {}
@@ -137,11 +139,7 @@ function getterFn (key, fn) {
   let getter = fn.get
 
   if (fn.hasOwnProperty('watch')) {
-    const previousGetter = getter
-    getter = function getter () {
-      fn.watch.call(this)
-      return previousGetter.call(this)
-    }
+    getter = getWatchedGetter(fn)
   }
 
   if (fn.hasOwnProperty('shouldUpdate')) {

src/watch.js

@@ -0,0 +1,41 @@
+const getGetterWatchedByArray = computedAsyncProperty =>
+  function getter() {
+    for (let key of computedAsyncProperty.watch) {
+      if (typeof key !== 'string') throw new Error('AsyncComputed: watch elemnts must be strings')
+      // check if nested key is watched
+      const splittedByDot = key.split('.');
+      if (splittedByDot.length === 1) {
+        // if not just access it
+        this[key]
+      } else {
+        // access nested propety
+        try {
+          var start = this
+          for (let part of splittedByDot) {
+            start = start[part]
+          }
+        } catch (error) {
+          console.error('computedAsyncPlugin: bad path: ', key)
+          throw error
+        }
+      }
+    }
+    return computedAsyncProperty.get.call(this)
+  }
+
+const getGetterWatchedByFunction = computedAsyncProperty =>
+  function getter() {
+    computedAsyncProperty.watch.call(this)
+    return computedAsyncProperty.get.call(this)
+  }
+
+
+export function getWatchedGetter(computedAsyncProperty) {
+  if (typeof computedAsyncProperty.watch === 'function') {
+    return getGetterWatchedByFunction(computedAsyncProperty)
+  } else if (Array.isArray(computedAsyncProperty.watch)) {
+    return getGetterWatchedByArray(computedAsyncProperty)
+  } else {
+    throw Error('AsyncComouted: watch should be function or an array')
+  }
+}

test/index.js

@@ -885,3 +885,132 @@ test('Data of component still work as function and got vm', t => {
   })
   t.equal(vm, _vmContext)
 })
+
+
+test("Watch as a function", t => {
+  t.plan(4)
+  let i = 0
+  const vm = new Vue({
+    data: {
+      y: 2,
+      obj: {
+        t: 0
+      }
+    },
+    asyncComputed: {
+      z: {
+        get () {
+          return Promise.resolve(i + this.y)
+        },
+        watch(){
+          this.obj.t
+        }
+      }
+    }
+  })
+  t.equal(vm.z, null)
+  Vue.nextTick(() => {
+    t.equal(vm.z, 2)
+    i++
+    vm.obj.t--
+    Vue.nextTick(() => {
+      // This tick, Vue registers the change
+      // in the watcher, and reevaluates
+      // the getter function
+      t.equal(vm.z, 2)
+      Vue.nextTick(() => {
+        // Now in this tick the promise has
+        // resolved, and z is 3.
+        t.equal(vm.z, 3)
+      })
+    })
+  })
+})
+
+
+test("Watchers as array with nested path rerun the computation when a value changes", t => {
+  t.plan(4)
+  let i = 0
+  const vm = new Vue({
+    data: {
+      y: 2,
+      obj: {
+        t: 0
+      }
+    },
+    asyncComputed: {
+      z: {
+        get () {
+          return Promise.resolve(i + this.y)
+        },
+        watch: ['obj.t']
+      }
+    }
+  })
+  t.equal(vm.z, null)
+  Vue.nextTick(() => {
+    t.equal(vm.z, 2)
+    i++
+    vm.obj.t--
+    Vue.nextTick(() => {
+      // This tick, Vue registers the change
+      // in the watcher, and reevaluates
+      // the getter function
+      t.equal(vm.z, 2)
+      Vue.nextTick(() => {
+        // Now in this tick the promise has
+        // resolved, and z is 3.
+        t.equal(vm.z, 3)
+      })
+    })
+  })
+})
+
+test("Watch as array with more then one value", t => {
+  t.plan(5)
+  let i = 0
+  const vm = new Vue({
+    data: {
+      y: 2,
+      obj: {
+        t: 0
+      },
+      r:0
+    },
+    asyncComputed: {
+      z: {
+        get () {
+          return Promise.resolve(i + this.y)
+        },
+        watch: ['obj.t', 'r']
+      }
+    }
+  })
+  t.equal(vm.z, null)
+  Vue.nextTick(() => {
+    t.equal(vm.z, 2)
+    i++
+    // checking for nested property
+    vm.obj.t--
+    Vue.nextTick(() => {
+      // This tick, Vue registers the change
+      // in the watcher, and reevaluates
+      // the getter function
+      t.equal(vm.z, 2)
+      Vue.nextTick(() => {
+        // Now in this tick the promise has
+        // resolved, and z is 3.
+        t.equal(vm.z, 3)
+
+        i++
+        // one level and multiple watchers
+        vm.r--
+        Vue.nextTick(()=>{
+          Vue.nextTick(() => {
+            t.equal(vm.z,4)
+          })
+        })
+      })
+    })
+  })
+})