Reinstate type checks in Math.min and Math.max

tests/lib/math/min_max_test.dart

 // Copyright (c) 2012, 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.
 // Dart test for testing Math.min and Math.max.
 // VMOptions=--optimization-counter-threshold=10
 
 library min_max_test;
 import "package:expect/expect.dart";
 import 'dart:math';
 
 var inf = double.INFINITY;
 var nan = double.NAN;
 
+// A class that might work if [min] and [max] worked for non-numbers.
+class Wrap implements Comparable {
+  final value;
+  Wrap(this.value);
+  int compare(Wrap other) => value.compare(other.value);
+  bool operator<(Wrap other) => compare(other) < 0;
+  bool operator<=(Wrap other) => compare(other) <= 0;
+  bool operator>(Wrap other) => compare(other) > 0;
+  bool operator>=(Wrap other) => compare(other) >= 0;
+  bool operator==(other) => other is Wrap && compare(other) == 0;
+  String toString() => 'Wrap($value)';
+}
+
+var wrap1 = new Wrap(1);
+var wrap2 = new Wrap(2);
+
 testMin() {
   testMin1();
   testMin2();
   testMin3();
+  testMinChecks();
 }
 
 testMin1() {
   Expect.equals(0, min(0, 2));
   Expect.equals(0, min(2, 0));
 
   Expect.equals(-10, min(-10, -9));
   Expect.equals(-10, min(-10, 9));
   Expect.equals(-10, min(-10, 0));
   Expect.equals(-10, min(-9, -10));
@@ skipping 244 matching lines @@
   Expect.isTrue(min(inf, -499.0).isNegative);
   Expect.isTrue(min(inf, -499).isNegative);
   Expect.isTrue(min(inf, -0.0).isNegative);
   Expect.isFalse(min(inf, 0.0).isNegative);
   Expect.isFalse(min(inf, 0).isNegative);
   Expect.isFalse(min(inf, 499).isNegative);
   Expect.isFalse(min(inf, 499.0).isNegative);
   Expect.isFalse(min(inf, inf).isNegative);
 }
 
+testMinChecks() {
+  // Min and max work only on numbers.
+  Expect.throws(() => min(wrap1, wrap2), (e) => e is ArgumentError);
+  Expect.throws(() => min(wrap1, 0), (e) => e is ArgumentError);
+  Expect.throws(() => min(0, wrap2), (e) => e is ArgumentError);
+}
+
 testMax() {
   testMax1();
   testMax2();
   testMax3();
+  testMaxChecks();
 }
 
 testMax1() {
   Expect.equals(2, max(0, 2));
   Expect.equals(2, max(2, 0));
 
   Expect.equals(-9, max(-10, -9));
   Expect.equals(9, max(-10, 9));
   Expect.equals(0, max(-10, 0));
   Expect.equals(-9, max(-9, -10));
@@ skipping 234 matching lines @@
   Expect.isTrue(max(-inf, -inf) is double);
 
   Expect.isFalse(max(-inf, 0.0).isNegative);
   Expect.isFalse(max(-inf, 0).isNegative);
   Expect.isTrue(max(-inf, -0.0).isNegative);
   Expect.isTrue(max(-inf, -499).isNegative);
   Expect.isTrue(max(-inf, -499.0).isNegative);
   Expect.isTrue(max(-inf, -inf).isNegative);
 }
 
+testMaxChecks() {
+  // Min and max work only on numbers.
+  Expect.throws(() => min(wrap1, wrap2), (e) => e is ArgumentError);
+  Expect.throws(() => min(wrap1, 0), (e) => e is ArgumentError);
+  Expect.throws(() => min(0, wrap2), (e) => e is ArgumentError);
+}
+
 main() {
   testMin();
   testMin();
   testMax();
   testMax();
 }