diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..40b878d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+node_modules/
\ No newline at end of file
diff --git a/nested-set-model.js b/nested-set-model.js
index 8b364c5..a6c6af0 100644
--- a/nested-set-model.js
+++ b/nested-set-model.js
@@ -1,20 +1,19 @@
 // nested set model (l;r) parent search
 
 var NestedSetModel = function(model, options) {
-
-    options = options || {};
-    this.leftKey = options.left || 'left';
-    this.rightKey =  options.right || 'key';
-
+    
+    var self = this;
     this.model = [];
     this.index = {};
 
-    var self = this;
+    this.options = options || {};
+    this.options.left = this.options.left || 'left'; 
+    this.options.right = this.options.right || 'right'; 
 
     // sort the set for deterministic order
     model.sort(function(a, b)
     {
-        return a[self.leftKey] - b[self.leftKey];
+        return a[self.options.left] - b[self.options.left];
     });
 
     // create an index
@@ -23,7 +22,7 @@ var NestedSetModel = function(model, options) {
             continue;
         }
 
-        this.index[model[index][this.rightKey]] = index;
+        this.index[model[index][this.options.right]] = index;
     }
 
     for(var entry in model) {
@@ -31,7 +30,7 @@ var NestedSetModel = function(model, options) {
             continue;
         }
 
-        var node = new NestedSetModelNode(model[entry], model, this.index);
+        var node = new NestedSetModelNode(model[entry], model, this.index, this.options);
         this.model.push(node);
     }
 
@@ -86,14 +85,15 @@ NestedSetModel.prototype.find = function(partial, strict) {
         if (!this.model.hasOwnProperty(key)) {
             continue;
         } else if (this.compareNodes(this.model[key], partial, strict)) {
-            return new NestedSetModelNode(this.model[key], this.model, this.index);
+            return new NestedSetModelNode(this.model[key], this.model, this.index, this.options);
         }
     }
 }
 
-var NestedSetModelNode = function(node, model, index) {
+var NestedSetModelNode = function(node, model, index, options) {
     this.model = model;
     this.index = index;
+    this.options = options;
 
     var self = this;
     Object.keys(node).forEach(function(prop) {
@@ -102,26 +102,28 @@ var NestedSetModelNode = function(node, model, index) {
 }
 
 NestedSetModelNode.prototype.parents = function() {
-    var parents = [];
+
     var self = this;
 
-    this.model.map(function(node) {
-        if (self[self.model.leftKey] > node[self.model.leftKey] && self[self.model.rightKey] < node[self.model.rightKey]) {
-            parents.push(new NestedSetModelNode(node, self.model, self.index));
+    return this.model.map(function(node) {
+        if (self[self.options.left] > node[self.options.left] && self[self.options.right] < node[self.options.right]) {
+            return new NestedSetModelNode(node, self.model, self.index, self.options);
         }
+        return null;
+    }).filter(function(item) {
+        return item !== null;
     });
 
-    return parents;
 }
 
 NestedSetModelNode.prototype.descendants = function() {
     var descendants = [];
-    var num_items = Math.floor((this.model.rightKey - this.model.leftKey) / 2);
+    var num_items = Math.floor((this[this.options.right] - this[this.options.left]) / 2);
 
     for(var right in this.index) {
-        if (right < this.model.rightKey && right > this.model.leftKey) {
+        if (right < this[this.options.right] && right > this[this.options.left]) {
             var node = this.model[this.index[right]];
-            descendants.push(new NestedSetModelNode(node, this.model, this.index));
+            descendants.push(new NestedSetModelNode(node, this.model, this.index, this.options));
         }
     }
 
@@ -130,16 +132,16 @@ NestedSetModelNode.prototype.descendants = function() {
 
 NestedSetModelNode.prototype.children = function() {
     var children = [];
-    var right = this.model.rightKey - 1;
+    var right = this[this.options.right] - 1;
 
     while(true) {
-        if (right === this.model.leftKey) {
+        if (right === this[this.options.left]) {
             break;
         }
 
         var child = this.model[this.index[right]];
-        children.push(new NestedSetModelNode(child, this.model, this.index));
-        right = child.model.leftKey - 1;
+        children.push(new NestedSetModelNode(child, this.model, this.index, this.options));
+        right = child[this.options.left] - 1;
     }
 
     return children.reverse();
@@ -147,7 +149,7 @@ NestedSetModelNode.prototype.children = function() {
 
 
 NestedSetModelNode.prototype.isLeaf = function() {
-    return this.model.rightKey - this.model.leftKey === 1;
+    return this[this.options.right] - this[this.options.left] === 1;
 }
 
 NestedSetModelNode.prototype.isParent = function() {
@@ -155,13 +157,12 @@ NestedSetModelNode.prototype.isParent = function() {
 }
 
 NestedSetModelNode.prototype.isDescendant = function() {
-    return this.model.leftKey > 0 && this.model.rightKey < (this.model.length * 2);
+    return this[this.options.left] > 0 && this[this.options.right] < (this.model.length * 2);
 }
 
 // bootstrap
 if (typeof define !== 'undefined') {
-	define('NestedSetModel', NestedSetModel);
+    define('NestedSetModel', NestedSetModel);
 } else if (typeof module !== 'undefined') {
     module.exports = NestedSetModel;
 }
-
diff --git a/package.json b/package.json
index c2f0a93..5460a7c 100644
--- a/package.json
+++ b/package.json
@@ -1,15 +1,21 @@
 {
-	"name": "nestedjs",
-	"version": "1.1.0",
-	"description": "A lightweight library for working with the Nested Set Model",
-	"author": "Ferdi Schmidt",
-	"main": "nested-set-model.js",
-	"repository": {
-		"url": "https://github.com/uitgewis/nestedjs"
-	},
-	"license": "BSD-2-Clause",
-	"keywords": [
-		"nested set",
-		"nested set model"
-	]
+  "name": "nestedjs",
+  "version": "1.1.0",
+  "description": "A lightweight library for working with the Nested Set Model",
+  "author": "Ferdi Schmidt",
+  "main": "nested-set-model.js",
+  "scripts": {
+    "test": "mocha"
+  },
+  "repository": {
+    "url": "https://github.com/uitgewis/nestedjs"
+  },
+  "license": "BSD-2-Clause",
+  "keywords": [
+    "nested set",
+    "nested set model"
+  ],
+  "devDependencies": {
+    "mocha": "^3.0.2"
+  }
 }
diff --git a/test/custom-keys.json b/test/custom-keys.json
new file mode 100644
index 0000000..de4375f
--- /dev/null
+++ b/test/custom-keys.json
@@ -0,0 +1,38 @@
+[
+    {
+        "id": 1,
+        "title": "root",
+        "lf": 1,
+        "rg": 12
+    },
+    {
+        "id": 4,
+        "title": "child",
+        "lf": 3,
+        "rg": 8
+    },
+    {
+        "id": 2,
+        "title": "parent",
+        "lf": 2,
+        "rg": 9
+    },
+    {
+        "id": 3,
+        "title": "middle",
+        "lf": 10,
+        "rg": 11
+    },
+    {
+        "id":5,
+        "title": "child",
+        "lf": 4,
+        "rg": 7
+    },
+    {
+        "id":6,
+        "title": "leaf",
+        "lf": 5,
+        "rg": 6
+    }
+]
\ No newline at end of file
diff --git a/test/fixture.json b/test/fixture.json
new file mode 100644
index 0000000..f61b0f9
--- /dev/null
+++ b/test/fixture.json
@@ -0,0 +1,38 @@
+[
+    {
+        "id": 1,
+        "title": "root",
+        "left": 1,
+        "right": 12
+    },
+    {
+        "id": 4,
+        "title": "child",
+        "left": 3,
+        "right": 8
+    },
+    {
+        "id": 2,
+        "title": "parent",
+        "left": 2,
+        "right": 9
+    },
+    {
+        "id": 3,
+        "title": "middle",
+        "left": 10,
+        "right": 11
+    },
+    {
+        "id":5,
+        "title": "child",
+        "left": 4,
+        "right": 7
+    },
+    {
+        "id":6,
+        "title": "leaf",
+        "left": 5,
+        "right": 6
+    }
+]
\ No newline at end of file
diff --git a/test/test.js b/test/test.js
new file mode 100644
index 0000000..441930e
--- /dev/null
+++ b/test/test.js
@@ -0,0 +1,62 @@
+var assert = require('assert');
+var NestedSetModel = require('./../nested-set-model');
+
+var fixture = require('./fixture.json');
+var customKeyFixture = require('./custom-keys.json');
+
+describe('NestedSetModel', function() {
+    describe('default configuration', function() {
+        it('should properly recognize leaf nodes', function() {
+            var model = new NestedSetModel(fixture);
+            assert(!model.find({ title: 'root' }).isLeaf())
+            assert(!model.find({ title: 'parent' }).isLeaf())
+            assert(!model.find({ title: 'child', left: 3 }).isLeaf())
+            assert(!model.find({ title: 'child', left: 4 }).isLeaf())
+            assert(model.find({ title: 'middle' }).isLeaf());
+            assert(model.find({ title: 'leaf' }).isLeaf());            
+        });
+        it('should properly recognize parent nodes', function() {
+            var model = new NestedSetModel(fixture);
+            assert(model.find({ title: 'root' }).isParent())
+            assert(model.find({ title: 'parent' }).isParent())
+            assert(model.find({ title: 'child', left: 3 }).isParent())
+            assert(model.find({ title: 'child', left: 4 }).isParent())
+            assert(!model.find({ title: 'middle' }).isParent());
+            assert(!model.find({ title: 'leaf' }).isParent());            
+        });
+        it('should return the correct set of children', function() {
+            var model = new NestedSetModel(fixture);
+            assert.strictEqual(model.find({ title: 'root' }).children().length, 2);
+            assert.strictEqual(model.find({ title: 'middle' }).children().length, 0);
+            assert.strictEqual(model.find({ title: 'child', left: 3 }).children().length, 1);
+            assert.strictEqual(model.find({ title: 'child', left: 4 }).children().length, 1);
+            assert.strictEqual(model.find({ title: 'leaf' }).children().length, 0);
+        });
+        it('should return the correct set of descendants', function() {
+            var model = new NestedSetModel(fixture);
+            assert.strictEqual(model.find({ title: 'root' }).descendants().length, 5);
+            assert.strictEqual(model.find({ title: 'middle' }).descendants().length, 0);
+            assert.strictEqual(model.find({ title: 'child', left: 3 }).descendants().length, 2);
+            assert.strictEqual(model.find({ title: 'child', left: 4 }).descendants().length, 1);
+            assert.strictEqual(model.find({ title: 'leaf' }).descendants().length, 0);
+        });
+        it('should return the correct set of parents', function() {
+            var model = new NestedSetModel(fixture);
+            assert.strictEqual(model.find({ title: 'root' }).parents().length, 0);
+            assert.strictEqual(model.find({ title: 'middle' }).parents().length, 1);
+            assert.strictEqual(model.find({ title: 'child', left: 3 }).parents().length, 2);
+            assert.strictEqual(model.find({ title: 'child', left: 4 }).parents().length, 3);
+            assert.strictEqual(model.find({ title: 'leaf' }).parents().length, 4);
+        });
+    });
+    describe('custom configuration', function() {
+        it('should properly walk the tree using the given keys', function() {
+            var model = new NestedSetModel(customKeyFixture, {left: 'lf', right: 'rg'});
+            assert(!model.find({ title: 'child' }).isLeaf())
+            assert(model.find({ title: 'leaf' }).isLeaf());
+            assert(model.find({ title: 'child' }).parents().length);
+            assert(model.find({ title: 'child' }).children().length);
+            assert(model.find({ title: 'child' }).descendants().length);
+        });
+    });
+});