Properly skip Set tests in browsers that don't really support it

spec/core/PrettyPrintSpec.js

@@ -15,13 +15,13 @@ describe("jasmineUnderTest.pp", function () {
   });
 
   describe('stringify sets', function() {
-    if (typeof Set === 'undefined') { return; }
-
     it("should stringify sets properly", function() {
+      jasmine.getEnv().requireFunctioningSets();
       expect(jasmineUnderTest.pp(new Set([1, 2]))).toEqual("Set( 1, 2 )");
     });
 
     it("should truncate sets with more elments than jasmineUnderTest.MAX_PRETTY_PRINT_ARRAY_LENGTH", function() {
+      jasmine.getEnv().requireFunctioningSets();
       var originalMaxSize = jasmineUnderTest.MAX_PRETTY_PRINT_ARRAY_LENGTH;
 
       try {

spec/core/matchers/matchersUtilSpec.js

@@ -369,12 +369,12 @@ describe("matchersUtil", function() {
     });
 
     it("passes when comparing two empty sets", function() {
-      if (typeof Set === 'undefined') { return; }
+      jasmine.getEnv().requireFunctioningSets();
       expect(jasmineUnderTest.matchersUtil.equals(new Set(), new Set())).toBe(true);
     });
 
     it("passes when comparing identical sets", function() {
-      if (typeof Set === 'undefined') { return; }
+      jasmine.getEnv().requireFunctioningSets();
       var setA = new Set([6, 5]);
       var setB = new Set();
       setB.add(6);
@@ -383,26 +383,25 @@ describe("matchersUtil", function() {
     });
 
     it("fails for sets with different elements", function() {
-      if (typeof Set === 'undefined') { return; }
+      jasmine.getEnv().requireFunctioningSets();
       var setA = new Set([6, 3, 5]);
       var setB = new Set([6, 4, 5]);
       expect(jasmineUnderTest.matchersUtil.equals(setA, setB)).toBe(false);
     });
 
     it("fails for sets of different size", function() {
-      if (typeof Set === 'undefined') { return; }
+      jasmine.getEnv().requireFunctioningSets();
       var setA = new Set([6, 3]);
       var setB = new Set([6, 4, 5]);
       expect(jasmineUnderTest.matchersUtil.equals(setA, setB)).toBe(false);
     });
 
     it("fails for sets with different insertion order", function() {
-      if (typeof Set === 'undefined') { return; }
+      jasmine.getEnv().requireFunctioningSets();
       var setA = new Set([3, 6]);
       var setB = new Set([6, 3]);
       expect(jasmineUnderTest.matchersUtil.equals(setA, setB)).toBe(false);
     });
-
   });
 
   describe("contains", function() {

spec/helpers/BrowserFlags.js

@@ -20,4 +20,23 @@
     return /Firefox\/([0-9]{0,})/.exec(userAgent);
   });
 
+  function hasFunctioningSets() {
+    if (typeof Set !== 'undefined') { return false; }
+
+    try {
+      var s = new Set([4]);
+      if (s.size !== 1) { return false; }
+      if (s.values().next().value !== 4) { return false; }
+      return true;
+    } catch(e) {
+      return false;
+    }
+  }
+
+  env.requireFunctioningSets = function() {
+    if (!hasFunctioningSets()) {
+      pending("Browser has incomplete or missing support for Sets");
+    }
+  };
+
 })(jasmine.getEnv());