Fixes #251 - Output of render should be Promise compatible.

runtime/OutMixins.js

@@ -71,6 +71,29 @@ module.exports = {
         return this;
     },
 
+    then: function(fn, fnErr) {
+        var self = this;
+        var promise = new Promise(function(resolve, reject) {
+            self.on('error', reject);
+            self.on('finish', function(data) {
+                try {
+                    resolve(fn(data));
+                } catch(err) {
+                    reject(err);
+                }
+            });
+        });
+
+        if (fnErr) {
+            promise = promise.catch(fnErr);
+        }
+        return promise;
+    },
+
+    catch: function(fnErr) {
+        return this.then(undefined, fnErr);
+    },
+
     appendTo: function(referenceEl) {
         var newNode = this.getNode(referenceEl.ownerDocument);
         dom.appendTo(newNode, referenceEl);

runtime/html/AsyncStream.js

@@ -221,7 +221,7 @@ var proto = AsyncStream.prototype = {
                if (state.writer.end) {
                    state.writer.end();
                } else {
-                   state.events.emit('finish');
+                   state.events.emit('finish', this);
                }
            }
        }
@@ -290,7 +290,7 @@ var proto = AsyncStream.prototype = {
         var state = this._state;
 
         if (event === 'finish' && state.finished) {
-            callback();
+            callback(this);
             return this;
         }
 
@@ -302,7 +302,7 @@ var proto = AsyncStream.prototype = {
         var state = this._state;
 
         if (event === 'finish' && state.finished) {
-            callback();
+            callback(this);
             return this;
         }
 

test/AsyncStream-test.js

@@ -57,6 +57,19 @@ describe('async-writer' , function() {
         });
     });
 
+    it('should resolve promise upon finish', function() {
+        var out = new AsyncStream();
+
+        out.write('1');
+        out.write('2');
+
+        return out.end().then((data) => {
+            const output = out.getOutput();
+            expect(output).to.equal('12');
+            expect(data.getOutput()).to.equal('12');
+        });
+    });
+
     it('should render a series of sync and async calls correctly', function(done) {
         var out = new AsyncStream();
         out.write('1');
@@ -250,6 +263,30 @@ describe('async-writer' , function() {
         });
     });
 
+    it('should catch error in promise catch', function(done) {
+        const out = new AsyncStream();
+
+        let errors = [];
+
+        out.on('error', function(e) {
+            errors.push(e);
+        });
+
+        out.write('1');
+
+        let asyncOut = out.beginAsync();
+        setTimeout(function() {
+            asyncOut.error(new Error('test'));
+        }, 10);
+
+        out.write('3');
+        out.end().catch((err) => {
+            expect(errors.length).to.equal(1);
+            expect(err).to.be.an('error');
+            done();
+        });
+    });
+
     it('should support chaining', function(done) {
         var errors = [];
         var out = new AsyncStream()

test/AsyncVDOMBuilder-test.js

@@ -41,6 +41,15 @@ it('async', function(done) {
     });
 });
 
+it('promise', function(done) {
+    const out = new AsyncVDOMBuilder();
+    out.element('div', {}, 0);
+    out.end().then((tree) => {
+        expect(tree.childNodes.length).to.equal(1);
+        done();
+    });
+});
+
 it('async flush', function(done) {
     var out = new AsyncVDOMBuilder();
     out.on('update', function(tree) {

test/autotests/api/load-render-promise/template.marko

@@ -0,0 +1 @@
+- Hello ${data.name}!

test/autotests/api/load-render-promise/test.js

@@ -0,0 +1,16 @@
+'use strict';
+
+const nodePath = require('path');
+
+exports.check = function(marko, markoCompiler, expect, done) {
+    let template = marko.load(nodePath.join(__dirname, 'template.marko'));
+
+    template.render({
+        name: 'John'
+    }).then((out) => {
+        expect(out.getOutput()).to.equal('Hello John!');
+        done();
+    }).catch((err) => {
+        done(err);
+    });
+};