Adding streams to dart:html.

tests/html/streams_test.dart

+library streams_test;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:async';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration();
+
+  test('simple', () {
+    var a = new TextInputElement();
+    document.body.append(a);
+
+    var callCount = 0;
+    a.onFocus.listen((Event e) {
+      ++callCount;
+    });
+
+    a.focus();
+    expect(callCount, 1);
+  });
+
+  // Validates that events are not automatically unsubscribed.
+  test('unsubscribeOnError', () {
+    var a = new TextInputElement();
+    document.body.append(a);
+
+    var b = new TextInputElement();
+    document.body.append(b);
+
+    var callCountOne = 0;
+    var callCountTwo = 0;
+    var callCountThree = 0;
+    // Unsubscribe on error handlers still get their events.

[Jennifer Messerly, 2013/01/11 21:57:17]

Q: what is the effect of unsubscribeOnError? I think it means the chain is
broken, in which case might be worth adding test for that

[blois, 2013/01/11 22:51:30]

We have no way of triggering unsubscribeOnError for DOM events- it would have to
come from a subsequent stream. From what I understand, unsubscribeOnError is
essentially a no-op for DOM event streams.

Not sure how to further test this without just re-iterating core streams tests,
but I can definitely add a test if I'm missing an angle.

[floitsch, 2013/01/11 22:55:45]

Correct. unsubscribeOnError (similar to the onError and onDone handlers) is not
used for the Html Streams.

[Jennifer Messerly, 2013/01/11 23:30:14]

Makes sense. Thanks for clarifying!

+    a.onFocus.listen((Event e) {
+      ++callCountOne;
+      throw 'this error should not cause any problems.';
+    }, unsubscribeOnError:true);

[Jennifer Messerly, 2013/01/11 21:57:17]

I think we usually have space after : in named args:

http://www.dartlang.org/articles/style-guide/#do-use-a-space-around--in-named...

[blois, 2013/01/11 22:51:30]

Done.

+
+    // Handler which throws an exception should still get events.
+    a.onFocus.listen((Event e) {
+      ++callCountTwo;
+      if (callCountTwo == 0) {
+        throw 'this error should not cause any problems.';
+      }
+    });
+
+    // Standard handler should still always get events
+    a.onFocus.listen((Event e) {
+      ++callCountThree;
+    });
+
+    a.focus();
+    b.focus();
+    a.focus();
+    expect(callCountOne, 2);
+    expect(callCountTwo, 2);
+    expect(callCountThree, 2);
+  });
+
+  // Validates that capturing events fire on parent before child.
+  test('capture', () {
+    var parent = new DivElement();
+    document.body.append(parent);
+
+    var child = new TextInputElement();
+    parent.append(child);
+
+    var childCallCount = 0;
+    var parentCallCount = 0;
+    Element.focusEvent.forTarget(parent, useCapture:true).listen((Event e) {
+      ++parentCallCount;
+      expect(childCallCount, 0);
+    });
+
+    Element.focusEvent.forTarget(child, useCapture:true).listen((Event e) {
+      ++childCallCount;
+      expect(parentCallCount, 1);
+    });
+
+    child.focus();
+    expect(childCallCount, 1);
+    expect(parentCallCount, 1);
+  });
+}