Remove direct mongo access from Schema.spec.js.

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -30,8 +30,12 @@ export class MongoStorageAdapter {
     });
   }
 
-  dropCollection(name: string) {
-    return this.connect.then(() => this.collection(name).then(collection => collection.drop()));
+  collectionExists(name: string) {
+    return this.connect().then(() => {
+      return this.database.listCollections({ name: name }).toArray();
+    }).then(collections => {
+      return collections.length > 0;
+    });
   }
 
   dropCollection(name: string) {

src/Controllers/DatabaseController.js

@@ -38,6 +38,10 @@ DatabaseController.prototype.collection = function(className) {
   return this.rawCollection(className);
 };
 
+DatabaseController.prototype.collectionExists = function(className) {
+  return this.adapter.collectionExists(this.collectionPrefix + className);
+};
+
 DatabaseController.prototype.rawCollection = function(className) {
   return this.adapter.collection(this.collectionPrefix + className);
 };