fix #489 - evaluate() should return a result which can be altered

@@ -667,7 +667,7 @@ Casper.prototype.evaluate = function evaluate(fn, context) {
     this.injectClientUtils();
     // function context
     if (arguments.length === 1) {
-        return this.page.evaluate(fn);
+        return utils.clone(this.page.evaluate(fn));
     } else if (arguments.length === 2) {
         // check for closure signature if it matches context
         if (utils.isObject(context) && eval(fn).length === Object.keys(context).length) {
@@ -679,7 +679,7 @@ Casper.prototype.evaluate = function evaluate(fn, context) {
         // phantomjs-style signature
         context = [].slice.call(arguments).slice(1);
     }
-    return this.page.evaluate.apply(this.page, [fn].concat(context));
+    return utils.clone(this.page.evaluate.apply(this.page, [fn].concat(context)));
 };
 
 /**

@@ -90,3 +90,23 @@ casper.test.begin('thenEvaluate() tests', 2, function(test) {
         test.done();
     });
 });
+
+// https://github.com/n1k0/casperjs/issues/489
+// https://groups.google.com/forum/?fromgroups=#!topic/casperjs/95IgDMFnEKM
+casper.test.begin("evaluate() returns a value which can be altered", 1, function(test) {
+    var list;
+
+    casper.start().then(function() {
+        list = this.evaluate(function() {
+            return [{a: 1}, {b: 2}];
+        });
+        var first = list[0];
+        first.a = 42;
+        test.assertEquals(list, [{a: 42}, {b: 2}],
+            'evaluate() returns a cloned value which can be altered');
+    });
+
+    casper.run(function() {
+        test.done();
+    });
+});