adding TTL option for redis cache adapter (#3397)

* adding TTL option for redis cache adapter

* adding test for RedisCacheAdapter

* Fixing adapater var name

* changing timeout

* updating default time

* Fix the redis cache spec to construct the cache with the anticipated ttl

make timeout values really really small so our test run fast :).

spec/RedisCacheAdapter.spec.js

@@ -0,0 +1,50 @@
+var RedisCacheAdapter = require('../src/Adapters/Cache/RedisCacheAdapter').default;
+
+describe('RedisCacheAdapter', function() {
+  var KEY = 'hello';
+  var VALUE = 'world';
+
+  function wait(sleep) {
+    return new Promise(function(resolve) {
+      setTimeout(resolve, sleep);
+    })
+  }
+
+  it('should get/set/clear', (done) => {
+    var cache = new RedisCacheAdapter({
+      ttl: NaN
+    });
+
+    cache.put(KEY, VALUE)
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).toEqual(VALUE))
+      .then(() => cache.clear())
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).toEqual(null))
+      .then(done);
+  });
+
+  it('should expire after ttl', (done) => {
+    var cache = new RedisCacheAdapter(null, 1);
+
+    cache.put(KEY, VALUE)
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).toEqual(VALUE))
+      .then(wait.bind(null, 2))
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).toEqual(null))
+      .then(done);
+  });
+
+  it('should find un-expired records', (done) => {
+    var cache = new RedisCacheAdapter(null, 5);
+
+    cache.put(KEY, VALUE)
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).toEqual(VALUE))
+      .then(wait.bind(null, 1))
+      .then(() => cache.get(KEY))
+      .then((value) => expect(value).not.toEqual(null))
+      .then(done);
+  });
+});