Add GroupSet and SetGroup classes.

test/union_set_test.dart

Index: test/union_set_test.dart
diff --git a/test/union_set_test.dart b/test/union_set_test.dart
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+++ b/test/union_set_test.dart
@@ -0,0 +1,222 @@
+// Copyright (c) 2016, 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 "package:test/test.dart";
+
+import "package:collection/collection.dart";
+
+void main() {
+  group("with an empty outer set", () {
+    var set;
+    setUp(() {
+      set = new UnionSet<int>(new Set());
+    });
+
+    test("length returns 0", () {
+      expect(set.length, equals(0));
+    });
+
+    test("contains() returns false", () {
+      expect(set.contains(0), isFalse);
+      expect(set.contains(null), isFalse);
+      expect(set.contains("foo"), isFalse);
+    });
+
+    test("lookup() returns null", () {
+      expect(set.lookup(0), isNull);
+      expect(set.lookup(null), isNull);
+      expect(set.lookup("foo"), isNull);
+    });
+
+    test("toSet() returns an empty set", () {
+      expect(set.toSet(), isEmpty);
+      expect(set.toSet(), isNot(same(set)));
+    });
+
+    test("map() doesn't run on any elements", () {
+      expect(set.map(expectAsync((_) {}, count: 0)), isEmpty);
+    });
+  });
+
+  group("with multiple disjoint sets", () {
+    var set;
+    setUp(() {
+      set = new UnionSet<int>.from([
+        new Set.from([1, 2]),
+        new Set.from([3, 4]),
+        new Set.from([5]),
+        new Set()
+      ], disjoint: true);
+    });
+
+    test("length returns the total length", () {
+      expect(set.length, equals(5));
+    });
+
+    test("contains() returns whether any set contains the element", () {
+      expect(set.contains(1), isTrue);
+      expect(set.contains(4), isTrue);
+      expect(set.contains(5), isTrue);
+      expect(set.contains(6), isFalse);
+    });
+
+    test("lookup() returns elements that are in any set", () {
+      expect(set.lookup(1), equals(1));
+      expect(set.lookup(4), equals(4));
+      expect(set.lookup(5), equals(5));
+      expect(set.lookup(6), isNull);
+    });
+
+    test("toSet() returns the union of all the sets", () {
+      expect(set.toSet(), unorderedEquals([1, 2, 3, 4, 5]));
+      expect(set.toSet(), isNot(same(set)));
+    });
+
+    test("map() maps the elements", () {
+      expect(set.map((i) => i * 2), unorderedEquals([2, 4, 6, 8, 10]));
+    });
+  });
+
+  group("with multiple overlapping sets", () {
+    var set;
+    setUp(() {
+      set = new UnionSet<int>.from([
+        new Set.from([1, 2, 3]),
+        new Set.from([3, 4]),
+        new Set.from([5, 1]),
+        new Set()
+      ]);
+    });
+
+    test("length returns the total length", () {
+      expect(set.length, equals(5));
+    });
+
+    test("contains() returns whether any set contains the element", () {
+      expect(set.contains(1), isTrue);
+      expect(set.contains(4), isTrue);
+      expect(set.contains(5), isTrue);
+      expect(set.contains(6), isFalse);
+    });
+
+    test("lookup() returns elements that are in any set", () {
+      expect(set.lookup(1), equals(1));
+      expect(set.lookup(4), equals(4));
+      expect(set.lookup(5), equals(5));
+      expect(set.lookup(6), isNull);
+    });
+
+    test("lookup() returns the first element in an ordered context", () {
+      var duration1 = new Duration(seconds: 0);
+      var duration2 = new Duration(seconds: 0);
+      expect(duration1, equals(duration2));
+      expect(duration1, isNot(same(duration2)));
+
+      var set = new UnionSet.from([
+        new Set.from([duration1]),
+        new Set.from([duration2])
+      ]);
+
+      expect(set.lookup(new Duration(seconds: 0)), same(duration1));
+    });
+
+    test("toSet() returns the union of all the sets", () {
+      expect(set.toSet(), unorderedEquals([1, 2, 3, 4, 5]));
+      expect(set.toSet(), isNot(same(set)));
+    });
+
+    test("map() maps the elements", () {
+      expect(set.map((i) => i * 2), unorderedEquals([2, 4, 6, 8, 10]));
+    });
+  });
+
+  group("after an inner set was modified", () {
+    var set;
+    setUp(() {
+      var innerSet = new Set.from([3, 7]);
+      set = new UnionSet<int>.from([
+        new Set.from([1, 2]),
+        new Set.from([5]),
+        innerSet
+      ]);
+
+      innerSet.add(4);
+      innerSet.remove(7);
+    });
+
+    test("length returns the total length", () {
+      expect(set.length, equals(5));
+    });
+
+    test("contains() returns true for a new element", () {
+      expect(set.contains(4), isTrue);
+    });
+
+    test("contains() returns false for a removed element", () {
+      expect(set.contains(7), isFalse);
+    });
+
+    test("lookup() returns a new element", () {
+      expect(set.lookup(4), equals(4));
+    });
+
+    test("lookup() doesn't returns a removed element", () {
+      expect(set.lookup(7), isNull);
+    });
+
+    test("toSet() returns the union of all the sets", () {
+      expect(set.toSet(), unorderedEquals([1, 2, 3, 4, 5]));
+      expect(set.toSet(), isNot(same(set)));
+    });
+
+    test("map() maps the elements", () {
+      expect(set.map((i) => i * 2), unorderedEquals([2, 4, 6, 8, 10]));
+    });
+  });
+
+  group("after the outer set was modified", () {
+    var set;
+    setUp(() {
+      var innerSet = new Set.from([6]);
+      var outerSet = new Set.from([
+        new Set.from([1, 2]),
+        new Set.from([5]),
+        innerSet
+      ]);
+
+      set = new UnionSet<int>(outerSet);
+      outerSet.remove(innerSet);
+      outerSet.add(new Set.from([3, 4]));
+    });
+
+    test("length returns the total length", () {
+      expect(set.length, equals(5));
+    });
+
+    test("contains() returns true for a new element", () {
+      expect(set.contains(4), isTrue);
+    });
+
+    test("contains() returns false for a removed element", () {
+      expect(set.contains(6), isFalse);
+    });
+
+    test("lookup() returns a new element", () {
+      expect(set.lookup(4), equals(4));
+    });
+
+    test("lookup() doesn't returns a removed element", () {
+      expect(set.lookup(6), isNull);
+    });
+
+    test("toSet() returns the union of all the sets", () {
+      expect(set.toSet(), unorderedEquals([1, 2, 3, 4, 5]));
+      expect(set.toSet(), isNot(same(set)));
+    });
+
+    test("map() maps the elements", () {
+      expect(set.map((i) => i * 2), unorderedEquals([2, 4, 6, 8, 10]));
+    });
+  });
+}