Add test for async template block

lib/models/__tests__/templateBlock.js

@@ -73,6 +73,29 @@ describe('TemplateBlock', function() {
             });
         });
 
+        pit('must accept an async function', function() {
+            var templateBlock = TemplateBlock.create('sayhello', function(block) {
+                return Promise()
+                .then(function() {
+                    return 'Hello ' + block.body;
+                });
+            });
+
+            // Create a fresh Nunjucks environment
+            var env = new nunjucks.Environment(null, { autoescape: false });
+
+            // Add template block to environement
+            var Ext = templateBlock.toNunjucksExt();
+            env.addExtension(templateBlock.getExtensionName(), new Ext());
+
+            // Render a template using the block
+            var src = '{% sayhello %}Samy{% endsayhello %}';
+            return Promise.nfcall(env.renderString.bind(env), src)
+            .then(function(res) {
+                expect(res).toBe('Hello Samy');
+            });
+        });
+
         pit('must handle nested blocks', function() {
             var templateBlock = new TemplateBlock({
                 name: 'yoda',