Improve tests for plugins with filters

lib/plugin.js

@@ -115,7 +115,10 @@ Plugin.prototype.getFilters = function() {
             return [
                 key,
                 function() {
-                    var ctx = this;
+                    var ctx = {
+                        ctx: this.ctx,
+                        book: that.book
+                    };
                     var args = Array.prototype.slice.apply(arguments);
                     var callback = _.last(args);
 

lib/template.js

@@ -69,14 +69,16 @@ var TemplateEngine = function(book) {
 
 
 // Add filter
-TemplateEngine.prototype.addFilter = function(key, filter) {
-    if (this.env.getFilter(filterName)) {
+TemplateEngine.prototype.addFilter = function(filterName, func) {
+    try {
+        this.env.getFilter(filterName);
         this.log.warn.ln("conflict in filters, '"+filterName+"' is already set");
         return false;
+    } catch(e) {
+        this.log.debug.ln("add filter '"+filterName+"'");
+        this.env.addFilter(filterName, func, true);
+        return true;
     }
-    this.log.debug.ln("add filter '"+key+"'");
-    this.env.addFilter(key, func, true);
-    return true;
 };
 
 // Render a string from the book

test/plugins.js

@@ -40,14 +40,39 @@ describe('Plugins', function () {
         var plugin = new Plugin(books[0], "filters");
         plugin.load("./filters", PLUGINS_ROOT);
 
+        before(function(done) {
+            qdone(books[0].plugins.load(plugin), done);
+        });
+
         it('should valid a plugin', function() {
             assert(plugin.isValid());
         });
 
         it('should return a map of filters', function() {
             var filters = plugin.getFilters();
-            assert.equal(_.size(filters), 1);
+            assert.equal(_.size(filters), 2);
             assert(filters["hello"]);
+            assert(filters["helloCtx"]);
+        });
+
+        it('should correctly extend template filters', function(done) {
+            qdone(
+                books[0].template.renderString('{{ "World"|hello }}')
+                .then(function(content) {
+                    assert.equal(content, "Hello World");
+                }),
+                done
+            );
+        });
+
+        it('should correctly set book as context', function(done) {
+            qdone(
+                books[0].template.renderString('{{ "root"|helloCtx }}')
+                .then(function(content) {
+                    assert.equal(content, "root:"+books[0].root);
+                }),
+                done
+            );
         });
     });
 });

test/plugins/filters/index.js

@@ -2,6 +2,9 @@ module.exports = {
     filters: {
         hello: function(text) {
             return "Hello "+text;
+        },
+        helloCtx: function(text) {
+        	return text+":"+this.book.root;
         }
     }
 };