Add tests for generic methods in strong mode

tests/language_strong/generic_methods_shadowing_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.
+
+library generic_methods_shadowing;

[eernst, 2017/03/09 14:55:03]

Not sure what makes this test 'shadowing'. A few words about the topic of this
test would again be nice.

[Dmitry Stefantsov, 2017/03/10 13:21:55]

Agree, I didn't include the comments the first time, unfortunately. I fixed it
now. Also, I rewrote the test, so that it's more compact and demonstrates the
intent clearly.

The idea was to define a generic function inside another generic function that
has a type parameter with the same name.

+
+import "package:expect/expect.dart";
+
+class Pair<T extends Comparable<T>, S extends Comparable<S>>
+    implements Comparable<Pair<T, S>> {
+  final T first;
+  final S second;
+
+  Pair(this.first, this.second);
+
+  @override
+  int compareTo(Pair<T, S> other) {
+    if (first.compareTo(other.first) == 0) {
+      return second.compareTo(other.second);
+    }
+
+    return first.compareTo(other.first);
+  }
+}
+
+void bubbleSort<T extends Comparable<T>, S extends Pair<T, T>>(List<S> list) {
+  void swap<T>(List<T> list, int i, int j) {
+    T t = list[i];
+    list[i] = list[j];
+    list[j] = t;
+
+    Expect.isTrue(t is T);
+    Expect.isTrue(t is S); // S is passed as T below, so T = S here

[floitsch, 2017/03/09 11:27:17]

Finish with ".".

[Dmitry Stefantsov, 2017/03/10 13:21:55]

I rewrote the test, so that it's more compact. And I watched my comments this
time :)

+  }
+
+  for (int n = list.length; n > 1; n--) {
+    for (int i = 1; i < n; i++) {
+      if (list[i - 1].compareTo(list[i]) > 0) {
+        swap<S>(list, i - 1, i);
+      }
+    }
+  }
+}
+
+main() {
+  List<Pair<String, String>> list = <Pair<String, String>>[
+    new Pair<String, String>("b", "b"),
+    new Pair<String, String>("b", "a"),
+    new Pair<String, String>("a", "b"),
+    new Pair<String, String>("a", "a"),
+  ];
+  bubbleSort<String, Pair<String, String>>(list);
+
+  Expect.isTrue(list[0].first == "a" && list[0].second == "a");
+  Expect.isTrue(list[1].first == "a" && list[1].second == "b");
+  Expect.isTrue(list[2].first == "b" && list[2].second == "a");
+  Expect.isTrue(list[3].first == "b" && list[3].second == "b");
+}