Add multi-caching promise support for Wrap

lib/multi_caching.js

@@ -145,6 +145,17 @@ var multiCaching = function(caches, 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; }
@@ -175,6 +186,9 @@ var multiCaching = function(caches, options) {
                     }
 
                     if (!self._isCacheableValue(data)) {
+                        if (typeof cb === 'object') {
+                            return cb.resolve(data);
+                        }
                         return cb();
                     }
 
@@ -186,6 +200,10 @@ var multiCaching = function(caches, options) {
                 });
             }
         });
+
+        if (typeof cb === 'object') {
+            return cb.promise;
+        }
     };
 
     /**

test/multi_caching.unit.js

@@ -970,6 +970,70 @@ describe("multiCaching", function() {
                 });
             });
         });
+
+        describe("using native promises", function() {
+            beforeEach(function() {
+                multiCache = multiCaching([memoryCache, memoryCache3]);
+            });
+
+            it("should be able to chain with simple promise", function(done) {
+                multiCache.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) {
+                multiCache.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) {
+                multiCache.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 catch a throw in cache function as a promise", function(done) {
+                multiCache.wrap('key', function() {
+                    throw '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) {
+                multiCache.wrap('key', function() {
+                    return;
+                })
+                .then(function(res) {
+                    assert.equal(res, undefined);
+                    done();
+                });
+            });
+        });
     });
 
     context("when instantiated with a non-Array 'caches' arg", function() {