Fix Template#evaluate "eating" previous character if null was ret…

…urned from `toTemplateReplacements` function.

CHANGELOG

@@ -1,3 +1,5 @@
+* Fix `Template#evaluate` "eating" previous character if `null` was returned from `toTemplateReplacements` function. (Nir, Jürgen Hörmann, kangax)
+
 * Do not use relatively slow `new RegExp` in `String#extractScripts`. (MIYAMUKO Katsuyuki, kangax)
 
 * Element#readAttribute should always return string values or `null`. Fix IE's broken attributes model by converting to string any non-string value returned by `getAttribute` which is identical to the same-named property. (Jason B, kangax)

src/lang/template.js

@@ -122,11 +122,11 @@ var Template = Class.create({
    *  with symbols replaced by corresponding object’s properties.
   **/
   evaluate: function(object) {
-    if (Object.isFunction(object.toTemplateReplacements))
+    if (object && Object.isFunction(object.toTemplateReplacements))
       object = object.toTemplateReplacements();
 
     return this.template.gsub(this.pattern, function(match) {
-      if (object == null) return '';
+      if (object == null) return (match[1] + '');
 
       var before = match[1] || '';
       if (before == '\\') return match[2];

test/unit/string_test.js

@@ -1,5 +1,6 @@
 new Test.Unit.Runner({
   testInterpret: function(){
+    console.profile(1);
     this.assertIdentical('true', String.interpret(true));
     this.assertIdentical('123',  String.interpret(123));
     this.assertIdentical('foo bar', String.interpret('foo bar'));
@@ -348,6 +349,12 @@ new Test.Unit.Runner({
       toTemplateReplacements: function() { return { name: this.name, job: this.getJob() } }
     };
     this.assertEqual('My name is Stephan, my job is Web developer', new Template(source).evaluate(subject));
+
+    var strActual = new Template('foo #{bar} baz').evaluate({
+      toTemplateReplacements: function(){ return null; }
+    });
+    this.assertIdentical('foo  baz', strActual);
+    this.assertIdentical('foo', new Template('foo#{bar}').evaluate(null));
   },
 
   testTemplateEvaluationCombined: function() {
@@ -551,5 +558,6 @@ new Test.Unit.Runner({
     this.assertIdentical(true, 'true'.evalJSON());
     this.assertIdentical(false, 'false'.evalJSON());
     this.assertEqual('"', '"\\""'.evalJSON());
+    console.profileEnd(1);
   }
 });