feature(change detection): implement barebone ChangeDetector

fixes #39

modules/change_detection/test/change_detector_spec.js

@@ -0,0 +1,64 @@
+import {describe, it, xit, expect} from 'test_lib/test_lib';
+
+import {List, ListWrapper} from 'facade/collection';
+
+import {
+  ChangeDetector,
+  ProtoWatchGroup,
+  WatchGroup,
+  WatchGroupDispatcher
+} from 'change_detection/change_detector';
+
+import {Record} from 'change_detection/record';
+
+export function main() {
+  describe('change_detection', function() {
+    describe('ChangeDetection', function() {
+      it('should do simple watching', function() {
+        var person = new Person('misko', 38);
+        var pwg = new ProtoWatchGroup();
+        pwg.watch('name', 'name', false); // TODO(vicb): remove opt shallow when supported
+        pwg.watch('age', 'age', false);
+        var dispatcher = new LoggingDispatcher();
+        var wg = pwg.instantiate(dispatcher);
+        wg.setContext(person);
+        var cd = new ChangeDetector(wg);
+        cd.detectChanges();
+        expect(dispatcher.log).toEqual(['name=misko', 'age=38']);
+        dispatcher.clear();
+        cd.detectChanges();
+        expect(dispatcher.log).toEqual([]);
+        person.age = 1;
+        person.name = "Misko";
+        cd.detectChanges();
+        expect(dispatcher.log).toEqual(['name=Misko', 'age=1']);
+      });
+    });
+  });
+}
+
+class Person {
+  constructor(name:string, age:number) {
+    this.name = name;
+    this.age = age;
+  }
+
+  toString() {
+    return 'name=' + this.name + ' age=' + this.age.toString();
+  }
+}
+
+class LoggingDispatcher extends WatchGroupDispatcher {
+  constructor() {
+    this.log = null;
+    this.clear();
+  }
+
+  clear() {
+    this.log = ListWrapper.create();
+  }
+
+  onRecordChange(record:Record, context) {
+    ListWrapper.push(this.log, context + '=' + record.currentValue.toString());
+  }
+}