Adding test case for issue #556

.editorconfig

@@ -0,0 +1,14 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+# Matches multiple files with brace expansion notation
+# Set default charset
+[*.{js,json,marko,yml}]
+charset = utf-8
+indent_style = space
+indent_size = 4

test/autotests/widgets-browser/state-watch-null-async/index.marko

@@ -0,0 +1,21 @@
+class {
+    onInput(input) {
+        this.state = {
+            error: null
+        };
+    }
+
+    submit() {
+        var self = this;
+
+        setTimeout(function() {
+            self.state.error = 'FATAL ERROR';
+        }, 50);
+    }
+}
+
+<form on-submit('submit')>
+    <p if(state.error)>
+        FATAL ERROR
+    </p>
+</form>

test/autotests/widgets-browser/state-watch-null-async/test.js

@@ -0,0 +1,15 @@
+// see https://github.com/marko-js/marko/issues/556
+var expect = require('chai').expect;
+
+module.exports = function(helpers, done) {
+    var widget = helpers.mount(require('./index'), {});
+
+    expect(widget.el.innerHTML).to.not.contain('FATAL ERROR');
+
+    helpers.triggerEvent(widget.getEl(), 'submit');
+
+    setTimeout(function() {
+        expect(widget.el.innerHTML).to.contain('FATAL ERROR');
+        done();
+    }, 100);
+};

test/util/BrowserHelpers.js

@@ -8,6 +8,12 @@ function BrowserHelpers() {
 }
 
 BrowserHelpers.prototype = {
+    triggerEvent: function(el, type) {
+        var ev = document.createEvent("Event");
+        ev.initEvent(type, true, true);
+        el.dispatchEvent(ev);
+    },
+
     triggerMouseEvent: function(el, type) {
         var ev = document.createEvent("MouseEvent");
         ev.initMouseEvent(
@@ -87,4 +93,4 @@ BrowserHelpers.prototype = {
     }
 };
 
-module.exports = BrowserHelpers;
+module.exports = BrowserHelpers;