Add Promise support when using cache.wrap

.jshintrc

@@ -20,6 +20,7 @@
 
     "predef"        : [  // Extra globals.
         "__dirname",
+        "Promise",
         "Buffer",
         "event",
         "exports",

lib/caching.js

@@ -69,6 +69,17 @@ var caching = function(args) {
             options = {};
         }
 
+        if (!cb) {
+            cb = Promise.defer();
+            var work2 = work;
+            work = function(cb) {
+                Promise.resolve().then(work2).then(function(res) {
+                    cb(null, res);
+                })
+                .catch(cb);
+            };
+        }
+
         var hasKey = callbackFiller.has(key);
         callbackFiller.add(key, {cb: cb, domain: process.domain});
         if (hasKey) { return; }
@@ -91,6 +102,9 @@ var caching = function(args) {
                     }
 
                     if (!self._isCacheableValue(data)) {
+                        if (typeof cb === 'object') {
+                            return cb.resolve(data);
+                        }
                         return cb();
                     }
 
@@ -104,6 +118,10 @@ var caching = function(args) {
                 });
             }
         });
+
+        if (typeof cb === 'object') {
+            return cb.promise;
+        }
     };
 
     /**

lib/callback_filler.js

@@ -12,6 +12,12 @@ CallbackFiller.prototype.fill = function(key, err, data) {
 
     waiting.forEach(function(task) {
         var taskDomain = task.domain || domain.create();
+        if (typeof task.cb === 'object') {
+            if (err) {
+                return taskDomain.bind(task.cb.reject)(err);
+            }
+            return taskDomain.bind(task.cb.resolve)(data);
+        }
         taskDomain.bind(task.cb)(err, data);
     });
 };

test/caching.unit.js

@@ -673,6 +673,62 @@ describe("caching", function() {
                 });
             });
         });
+
+        describe("using native promises", function() {
+            beforeEach(function() {
+                cache = caching({
+                    store: 'memory',
+                    max: 50,
+                    ttl: 5 * 60
+                });
+            });
+
+            it("should be able to chain with simple promise", function(done) {
+                cache.wrap('key', function() {
+                    return 'OK';
+                })
+                .then(function(res) {
+                    assert.equal(res, 'OK');
+                    done();
+                });
+            });
+
+            it("should be able to chain with cache function as a promise", function(done) {
+                cache.wrap('key', function() {
+                    return new Promise(function(resolve) {
+                        resolve('OK');
+                    });
+                })
+                .then(function(res) {
+                    assert.equal(res, 'OK');
+                    done();
+                });
+            });
+
+            it("should be able to catch errors in cache function as a promise", function(done) {
+                cache.wrap('key', function() {
+                    return new Promise(function(resolve, reject) {
+                        reject('NOK');
+                    });
+                })
+                .then(function() {
+                    done(new Error('It should not call then since there is an error in the cache function!'));
+                })
+                .catch(function() {
+                    done();
+                });
+            });
+
+            it("should be able to chain with non-cacheable value", function(done) {
+                cache.wrap('key', function() {
+                    return;
+                })
+                .then(function(res) {
+                    assert.equal(res, undefined);
+                    done();
+                });
+            });
+        });
     });
 
     describe("instantiating with no store passed in", function() {