Implement promise.finally (closes #116)

lib/vow.js

@@ -434,6 +434,25 @@ Promise.prototype = /** @lends Promise.prototype */ {
         return this.then(cb, cb, ctx);
     },
 
+    /**
+     * Adds a resolving reaction (for both fulfillment and rejection). The returned promise will be fullfiled with the same value or rejected with the same reason as the original promise.
+     *
+     * @param {Function} onFinalized Callback that will be invoked after the promise has been resolved.
+     * @param {Object} [ctx] Context of the callback execution
+     * @returns {vow:Promise}
+     */
+    'finally' : function(onFinalized, ctx) {
+        var _this = this,
+            cb = function() {
+                return onFinalized.call(this);
+            };
+        return this
+            .then(cb, cb, ctx)
+            .then(function() {
+                return _this;
+            });
+    },
+
     /**
      * Adds a progress reaction.
      *

test/promise.finally.js

@@ -0,0 +1,61 @@
+module.exports = {
+    'onFinalized callback should be called without arguments on fulfill' : function(test) {
+        var defer = Vow.defer();
+        defer.resolve('ok');
+        defer.promise().finally(function() {
+            test.strictEqual(arguments.length, 0);
+            test.done();
+        });
+    },
+
+    'onFinalized callback should be called without arguments on reject' : function(test) {
+        var defer = Vow.defer();
+        defer.reject('error');
+        defer.promise().finally(function() {
+            test.strictEqual(arguments.length, 0);
+            test.done();
+        });
+    },
+
+    'returned promise should be fulfilled with value of original promise' : function(test) {
+        var defer = Vow.defer();
+        defer.resolve('ok');
+        defer.promise()
+            .finally(function() {
+                return 'finally';
+            })
+            .then(function(val) {
+                test.strictEqual(val, 'ok');
+                test.done();
+            });
+    },
+
+    'returned promise should be rejected with value of original promise' : function(test) {
+        var defer = Vow.defer(),
+            error = new Error('error');
+        defer.reject(error);
+        defer.promise()
+            .finally(function() {
+                return new Error('finally');
+            })
+            .fail(function(_error) {
+                test.strictEqual(_error, error);
+                test.done();
+            });
+    },
+
+    'returned promise should be rejected with value of returned promise' : function(test) {
+        var defer = Vow.defer(),
+            error = new Error('error'),
+            finallyError = new Error('finally');
+        defer.reject(error);
+        defer.promise()
+            .finally(function() {
+                return Vow.reject(finallyError);
+            })
+            .fail(function(_error) {
+                test.strictEqual(_error, finallyError);
+                test.done();
+            });
+    }
+};

test/utils/runner.js

@@ -19,4 +19,4 @@ require('nodeunit').reporters.default.run(
             require('promises-aplus-tests')(require('./aplus-adapter'), function(err) {
                 err && process.exit(1);
             });
-    });
+    });