Add `byteCollector` stream transformer and `collectBytes` function.

test/byte_collection_test.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:async";
+import "dart:typed_data";
+
+import "package:test/test.dart";
+import "package:async/async.dart" show byteCollector, collectBytes, Result;
+
+void main() {
+  group("collectBytes", () {
+    test("simple list and overflow", () {
+      Future<Uint8List> result = collectBytes(streamOf([[0], [1], [2], [256]]));

[nweiz, 2017/01/25 23:00:40]

"var", also below.

[Lasse Reichstein Nielsen, 2017/01/26 09:43:06]

Done.

+      var expected = new Uint8List.fromList([0, 1, 2, 0]);

[nweiz, 2017/01/25 23:00:40]

Just compare against a plain list—test doesn't validate that the types match
exactly.

[Lasse Reichstein Nielsen, 2017/01/26 09:43:06]

Done.

+      expect(result, completion(expected));
+    });
+
+    test("no events", () {
+      Future<Uint8List> result = collectBytes(streamOf([]));
+      var expected = new Uint8List(0);
+      expect(result, completion(expected));
+    });
+
+    test("empty events", () {
+      Future<Uint8List> result = collectBytes(streamOf([[], []]));
+      var expected = new Uint8List(0);
+      expect(result, completion(expected));
+    });
+
+    test("error event", () {
+      Future<Uint8List> result = collectBytes(streamOf(
+          new Iterable.generate(3, (n) => n == 2 ? throw "badness" : [n])));
+      expect(result, throwsA("badness"));
+    });
+  });
+
+  group ("byteCollector", () {
+    test("simple list and overflow", () {
+      var stream = streamOf([[0], [1], [2], [256]]);
+      Stream<Uint8List> result = stream.transform(byteCollector);
+      var expected = new Uint8List.fromList([0, 1, 2, 0]);
+      expect(result.single, completion(expected));
+    });
+
+    test("no events", () {
+      Stream<Uint8List> result = streamOf([]).transform(byteCollector);
+      var expected = new Uint8List(0);
+      expect(result.single, completion(expected));
+    });
+
+    test("empty events", () {
+      Stream<Uint8List> result = streamOf([[], []]).transform(byteCollector);
+      var expected = new Uint8List(0);
+      expect(result.single, completion(expected));
+    });
+
+    test("error event", () async {
+      var stream = streamOf(
+          new Iterable.generate(3, (n) => n == 2 ? throw "badness" : [n]));
+      Stream<Uint8List> result = stream.transform(byteCollector);
+      var expected = new Uint8List.fromList([0, 1]);
+      var results = await Result.captureStream(result).toList();
+      expect(results[0].asFuture, throwsA("badness"));
+      expect(results[1].asFuture, completion(expected));
+      expect(results.length, 2);
+    });
+
+    test("multiple error events", () async {
+      var stream = () async* {
+        yield [0];
+        yield* new Future.error("badness1").asStream();
+        yield [2];
+        yield* new Future.error("badness3").asStream();
+        yield [4];
+      }();
+      Stream<Uint8List> result = stream.transform(byteCollector);
+      var expected = new Uint8List.fromList([0, 2, 4]);
+      var results = await Result.captureStream(result).toList();
+      expect(results[0].asFuture, throwsA("badness1"));
+      expect(results[1].asFuture, throwsA("badness3"));
+      expect(results[2].asFuture, completion(expected));
+      expect(results.length, 3);
+    });
+
+
+

[nweiz, 2017/01/25 23:00:40]

Extra empty lines.

[Lasse Reichstein Nielsen, 2017/01/26 09:43:06]

Done.

+  });
+
+
+
+
+
+}
+
+streamOf(Iterable<List<int>> lists) async* {

[nweiz, 2017/01/25 23:00:40]

Why not just use new Stream.fromIterable()?

[Lasse Reichstein Nielsen, 2017/01/26 09:43:06]

Too easy!
I had something more complicated here originally, but now you are right, I could
just use Stream.fromIterable.

+  for (var list in lists) yield list;
+}
+
+
+