Repository: Yoctol/bottender (ts)

Issue:
[Fb Messenger] - Error about user
With this new policy about facebook now i'm getting this error:

```
TypeError: Cannot assign to read only property 'user' of object '#<Object>'
    at MessengerConnector.updateSession (C:\Users\Avell\projetos\asksuite-facebook\node_modules\bottender\lib\bot\MessengerConnector.js:160:20)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:169:7)
```


Pull request description:
deepClone when read from MemoryCacheStore
cloneDeep: To make sure read as different object to prevent reading same key multiple times, causing freezed by other events.

fix #221
maybe related with #231 

Patch:
diff --git a/src/cache/MemoryCacheStore.js b/src/cache/MemoryCacheStore.js
index 62fc8890..be6d1976 100644
--- a/src/cache/MemoryCacheStore.js
+++ b/src/cache/MemoryCacheStore.js
@@ -13,7 +13,12 @@ export default class MemoryCacheStore implements CacheStore {
   }
 
   async get(key: string): Promise<mixed> {
-    const value = await this._lru.get(key);
+    const _value = this._lru.get(key);
+
+    // cloneDeep: To make sure read as different object to prevent
+    // reading same key multiple times, causing freezed by other events.
+    const value = typeof _value === 'object' ? cloneDeep(_value) : _value;
+
     return value || null;
   }
 


Test patch:
diff --git a/src/cache/__tests__/MemoryCacheStore.spec.js b/src/cache/__tests__/MemoryCacheStore.spec.js
index ecfa5271..cd6c19c1 100644
--- a/src/cache/__tests__/MemoryCacheStore.spec.js
+++ b/src/cache/__tests__/MemoryCacheStore.spec.js
@@ -8,6 +8,18 @@ describe('#get', () => {
     expect(await store.get('x')).toBe('abc');
   });
 
+  it('should get different object when get multiple times', async () => {
+    const store = new MemoryCacheStore(5);
+
+    await store.put('x', { a: 1 }, 5);
+
+    const result1 = await store.get('x');
+    const result2 = await store.get('x');
+
+    expect(result1).not.toBe(result2);
+    expect(result1).toEqual(result2);
+  });
+
   it('should get null when value does not exist', async () => {
     const store = new MemoryCacheStore(5);