Adding Caching Adapter, allows caching of _Role and _User queries (fixes #168) (#1664)

* Adding Caching Adapter, allows caching of _Role and _User queries.

spec/InMemoryCache.spec.js

@@ -0,0 +1,74 @@
+const InMemoryCache = require('../src/Adapters/Cache/InMemoryCache').default;
+
+
+describe('InMemoryCache', function() {
+  var BASE_TTL = {
+    ttl: 10
+  };
+  var NO_EXPIRE_TTL = {
+    ttl: NaN
+  };
+  var KEY = 'hello';
+  var KEY_2 = KEY + '_2';
+
+  var VALUE = 'world';
+
+
+  function wait(sleep) {
+    return new Promise(function(resolve, reject) {
+      setTimeout(resolve, sleep);
+    })
+  }
+
+  it('should destroy a expire items in the cache', (done) => {
+    var cache = new InMemoryCache(BASE_TTL);
+
+    cache.put(KEY, VALUE);
+
+    var value = cache.get(KEY);
+    expect(value).toEqual(VALUE);
+
+    wait(BASE_TTL.ttl * 5).then(() => {
+      value = cache.get(KEY)
+      expect(value).toEqual(null);
+      done();
+    });
+  });
+
+  it('should delete items', (done) => {
+    var cache = new InMemoryCache(NO_EXPIRE_TTL);
+    cache.put(KEY, VALUE);
+    cache.put(KEY_2, VALUE);
+    expect(cache.get(KEY)).toEqual(VALUE);
+    expect(cache.get(KEY_2)).toEqual(VALUE);
+
+    cache.del(KEY);
+    expect(cache.get(KEY)).toEqual(null);
+    expect(cache.get(KEY_2)).toEqual(VALUE);
+
+    cache.del(KEY_2);
+    expect(cache.get(KEY)).toEqual(null);
+    expect(cache.get(KEY_2)).toEqual(null);
+    done();
+  });
+
+  it('should clear all items', (done) => {
+    var cache = new InMemoryCache(NO_EXPIRE_TTL);
+    cache.put(KEY, VALUE);
+    cache.put(KEY_2, VALUE);
+
+    expect(cache.get(KEY)).toEqual(VALUE);
+    expect(cache.get(KEY_2)).toEqual(VALUE);
+    cache.clear();
+
+    expect(cache.get(KEY)).toEqual(null);
+    expect(cache.get(KEY_2)).toEqual(null);
+    done();
+  });
+
+  it('should deafult TTL to 5 seconds', () => {
+    var cache = new InMemoryCache({});
+    expect(cache.ttl).toEqual(5 * 1000);
+  });
+
+});