tests: Add test for checkall toogle state tracking

ref #795

xref #1538 #1539

tests/test.js

@@ -148,6 +148,16 @@ module.exports.todoMVCTest = function (frameworkName, baseUrl, speedMode, laxMod
 				testOps.assertItemAtIndexIsCompleted(2);
 			});
 
+			test.it('should correctly update the complete all checked state', function () {
+				// manually check all items
+				page.toggleItemAtIndex(0);
+				page.toggleItemAtIndex(1);
+				page.toggleItemAtIndex(2);
+
+				// ensure checkall is in the correct state
+				testOps.assertCompleteAllIsChecked();
+			});
+
 			test.it('should allow me to clear the completion state of all items', function () {
 				page.clickMarkAllCompletedCheckBox();
 				page.clickMarkAllCompletedCheckBox();