Change path-observer to lookup properties aggressively and report errors

pkg/observe/test/path_observer_test.dart

Index: pkg/observe/test/path_observer_test.dart
diff --git a/pkg/observe/test/path_observer_test.dart b/pkg/observe/test/path_observer_test.dart
index 8d71680a39e0c3af1f3cfc1d27889e87c083db18..8395eb948b986657d0c20c947c830925ab38de2b 100644
--- a/pkg/observe/test/path_observer_test.dart
+++ b/pkg/observe/test/path_observer_test.dart
@@ -9,7 +9,6 @@ import 'observe_test_utils.dart';
 
 // This file contains code ported from:
 // https://github.com/rafaelw/ChangeSummary/blob/master/tests/test.js
-
 main() => dirtyCheckZone().run(() {
   group('PathObserver', observePathTests);
 
@@ -68,26 +67,32 @@ main() => dirtyCheckZone().run(() {
   });
 });
 
-
 observePathTests() {
   test('Degenerate Values', () {
     expect(new PathObserver(null, '').value, null);
     expect(new PathObserver(123, '').value, 123);
-    expect(new PathObserver(123, 'foo.bar.baz').value, null);
-
-    // shouldn't throw:
-    new PathObserver(123, '')..open((_) {})..close();
-    new PropertyPath('').setValueFrom(null, null);
-    new PropertyPath('').setValueFrom(123, 42);
-    new PropertyPath('foo.bar.baz').setValueFrom(123, 42);
-
-    var foo = {};
-    expect(new PathObserver(foo, '').value, foo);
-
-    foo = new Object();
-    expect(new PathObserver(foo, '').value, foo);
-
-    expect(new PathObserver(foo, 'a/3!').value, null);
+    new Future(() {}).then((_) {

[Jennifer Messerly, 2014/03/25 22:32:44]

return the Future?

also does it work to start with:

return new Future(() {
  ...
}).then(...

[Siggi Cherem (dart-lang), 2014/03/26 00:32:07]

(obsolete)

+      // should throw:
+      return _asyncError('foo',
+          () => expect(new PathObserver(123, 'foo.bar.baz').value, null));

[Jennifer Messerly, 2014/03/25 22:32:44]

as noted earlier, I'd expect this error to be sync.

[Siggi Cherem (dart-lang), 2014/03/26 00:32:07]

Done.

+    }).then((_) {
+      // shouldn't throw:
+      new PathObserver(123, '')..open((_) {})..close();
+      new PropertyPath('').setValueFrom(null, null);
+      new PropertyPath('').setValueFrom(123, 42);
+
+      // should throw:
+      return _asyncError('foo',

[Jennifer Messerly, 2014/03/25 22:32:44]

when i'm changing behavior w.r.t. JS I usually put in a note like:

Dart note: getting invalid properties is an error, unlike in JS where it returns
undefined.

maybe just one note at the top since it's common to several tests

[Siggi Cherem (dart-lang), 2014/03/26 00:32:07]

Done (made the note on the source code too)

+        () => new PropertyPath('foo.bar.baz').setValueFrom(123, 42));
+    }).then((_) {
+      var foo = {};
+      expect(new PathObserver(foo, '').value, foo);
+
+      foo = new Object();
+      expect(new PathObserver(foo, '').value, foo);
+
+      expect(new PathObserver(foo, 'a/3!').value, null);
+    });
   });
 
   test('get value at path ObservableBox', () {
@@ -105,8 +110,9 @@ observePathTests() {
     expect(new PathObserver(obj, 'value.value.value').value, 3);
 
     obj.value = new ObservableBox(4);
-    expect(new PathObserver(obj, 'value.value.value').value, null);
     expect(new PathObserver(obj, 'value.value').value, 4);
+    return _asyncError('value',
+        () => expect(new PathObserver(obj, 'value.value.value').value, null));
   });
 
 
@@ -125,8 +131,9 @@ observePathTests() {
     expect(new PathObserver(obj, 'a.b.c').value, 3);
 
     obj['a'] = toObservable({'b': 4});
-    expect(new PathObserver(obj, 'a.b.c').value, null);
     expect(new PathObserver(obj, 'a.b').value, 4);
+    return _asyncError('c',
+        () => expect(new PathObserver(obj, 'a.b.c').value, null));
   });
 
   test('set value at path', () {
@@ -138,8 +145,13 @@ observePathTests() {
     new PropertyPath('bar').setValueFrom(obj, bar);
     expect(obj['bar'], bar);
 
-    new PropertyPath('bar.baz.bat').setValueFrom(obj, 'not here');
-    expect(new PathObserver(obj, 'bar.baz.bat').value, null);
+    new Future(() {}).then((_) {
+      return _asyncError('bat=',
+          () => new PropertyPath('bar.baz.bat').setValueFrom(obj, 'not here'));
+    }).then((_) {
+      return _asyncError('bat',
+          () => expect(new PathObserver(obj, 'bar.baz.bat').value, null));
+    });
   });
 
   test('set value back to same', () {
@@ -239,7 +251,9 @@ observePathTests() {
 
       var path = new PathObserver(model, 'a.b.c');
       var lastValue = null;
-      path.open((x) { lastValue = x; });
+      var errorSeen = false;
+      var future = _asyncError('c', () => path.open((x) { lastValue = x; }))
+          .then((_) { errorSeen = true; });
 
       model.a.b.c = 'hello, mom';
 
@@ -257,7 +271,9 @@ observePathTests() {
         expect(lastValue, 'hello, you');
 
         model.a.b = 1;
-      }).then(newMicrotask).then((_) {
+        expect(errorSeen, false); // update will be seen on next micro task
+      }).then((_) => future).then((_) {
+        expect(errorSeen, true);
         expect(lastValue, null);
 
         // Stop observing
@@ -300,11 +316,14 @@ observePathTests() {
     var model = new ObjectWithErrors();
     var observer = new PathObserver(model, 'foo');
 
-    expect(() => observer.value, throws);
-    expect(model.getFooCalled, 1);
-
-    expect(() { observer.value = 123; }, throws);
-    expect(model.setFooCalled, [123]);
+    new Future(() {}).then((_) {
+      return _asyncError('bar', () => observer.value);
+    }).then((_) {
+      expect(model.getFooCalled, 1);
+      return _asyncError('bar=', () { observer.value = 123; });
+    }).then((_) {
+      expect(model.setFooCalled, [123]);
+    });
   });
 
   test('object with noSuchMethod', () {
@@ -352,6 +371,24 @@ observePathTests() {
   });
 }
 
+_asyncError(String missingPropertyName, Function code) {
+  var completer = new Completer();
+  runZoned(() {
+    code();
+    return new Future(() {});
+  }, onError: (e) {
+    completer.complete(true);
+    expect(e, predicate((e) => e is NoSuchMethodError));
+
+    // Dart2js and VM error messages are a bit different, but they are both
+    // contain the missingPropertyName.
+    expect('$e', predicate((message) =>
+      message.contains("'$missingPropertyName'") || // VM error
+      message.contains('\'Symbol("$missingPropertyName")\''))); // dart2js error
+  });
+  return completer.future;
+}
+
 class ObjectWithErrors {
   int getFooCalled = 0;
   List setFooCalled = [];
@@ -383,7 +420,7 @@ class NoSuchMethodModel {
   }
 }
 
-class IndexerModel {
+class IndexerModel implements StringIndexer {
   var _foo = 42;
   List log = [];