fix(shareObservable): implement refCount like behavior

src/utils/shareObservable.js

@@ -3,23 +3,24 @@ import createObservable from './createObservable'
 
 const shareObservable = (observable) => {
   const observers = []
-  let emitted
+  let emitted = false
   let lastValue
-
-  observable.subscribe({
-    next: (value) => {
-      emitted = true
-      lastValue = value
-      observers.forEach(o => o.next(value))
-    },
-    complete: value => observers.forEach(o => o.complete(value)),
-    error: error => observers.forEach(o => o.error(error)),
-  })
+  let subscription = null
 
   return createObservable((observer) => {
     observers.push(observer)
 
-    if (emitted) {
+    if (!subscription) {
+      subscription = observable.subscribe({
+        next: (value) => {
+          emitted = true
+          lastValue = value
+          observers.forEach(o => o.next(value))
+        },
+        complete: value => observers.forEach(o => o.complete(value)),
+        error: error => observers.forEach(o => o.error(error)),
+      })
+    } else if (emitted) {
       observers.forEach(o => o.next(lastValue))
     }
 
@@ -28,6 +29,12 @@ const shareObservable = (observable) => {
         const index = observers.indexOf(observer)
         if (index === -1) return
         observers.splice(index, 1)
+
+        if (observers.length === 0) {
+          subscription.unsubscribe()
+          emitted = false
+          subscription = null
+        }
       },
     }
   })