diff --git a/js/apps/system/sessions/.gitignore b/js/apps/system/sessions/.gitignore
new file mode 100644
index 0000000000..3c3629e647
--- /dev/null
+++ b/js/apps/system/sessions/.gitignore
@@ -0,0 +1 @@
+node_modules
diff --git a/js/apps/system/sessions/errors.js b/js/apps/system/sessions/errors.js
index b55816c382..b6b1686244 100644
--- a/js/apps/system/sessions/errors.js
+++ b/js/apps/system/sessions/errors.js
@@ -2,14 +2,19 @@
 /*global require, exports */
 (function () {
   'use strict';
-
   function SessionNotFound(sid) {
     this.message = 'Session with session id ' + sid + ' not found.';
+    var err = new Error(this.message);
+    err.name = this.constructor.name;
+    this.stack = err.stack;
   }
   SessionNotFound.prototype = new Error();
 
   function SessionExpired(sid) {
     this.message = 'Session with session id ' + sid + ' has expired.';
+    var err = new Error(this.message);
+    err.name = this.constructor.name;
+    this.stack = err.stack;
   }
   SessionExpired.prototype = Object.create(SessionNotFound.prototype);
 
diff --git a/js/apps/system/sessions/package.json b/js/apps/system/sessions/package.json
new file mode 100644
index 0000000000..b0ca357fbe
--- /dev/null
+++ b/js/apps/system/sessions/package.json
@@ -0,0 +1,12 @@
+{
+  "private": true,
+  "devDependencies": {
+    "expect.js": "^0.3.1",
+    "mocha": "^1.21.4",
+    "mockuire": "^0.1.0",
+    "sinon": "^1.10.3"
+  },
+  "scripts": {
+    "test": "mocha --growl"
+  }
+}
diff --git a/js/apps/system/sessions/test/errors.js b/js/apps/system/sessions/test/errors.js
new file mode 100644
index 0000000000..f56fd29f6c
--- /dev/null
+++ b/js/apps/system/sessions/test/errors.js
@@ -0,0 +1,33 @@
+/*jslint indent: 2, nomen: true, maxlen: 120, es5: true */
+/*global require, describe, it */
+(function () {
+  'use strict';
+  var expect = require('expect.js'),
+    errors = require('../errors');
+
+  describe('errors', function () {
+    ['SessionNotFound', 'SessionExpired'].forEach(function (name) {
+      describe(name, function () {
+        var SessionError = errors[name];
+        it('is a constructor', function () {
+          expect(new SessionError()).to.be.a(SessionError);
+        });
+        it('creates an Error', function () {
+          expect(new SessionError()).to.be.an(Error);
+        });
+        it('uses its argument in its message', function () {
+          var err = new SessionError('potato');
+          expect(err.message).to.contain('potato');
+        });
+        it('uses its message in its stack trace', function () {
+          var err = new SessionError('potato');
+          expect(err.stack).to.contain(err.message);
+        });
+        it('uses its name in its stack trace', function () {
+          var err = new SessionError();
+          expect(err.stack).to.contain(name);
+        });
+      });
+    });
+  });
+}());
\ No newline at end of file
diff --git a/js/apps/system/sessions/test/setup.js b/js/apps/system/sessions/test/setup.js
new file mode 100644
index 0000000000..be55a700e9
--- /dev/null
+++ b/js/apps/system/sessions/test/setup.js
@@ -0,0 +1,45 @@
+/*jslint indent: 2, nomen: true, maxlen: 120, es5: true */
+/*global require, module, describe, it, beforeEach */
+(function () {
+  'use strict';
+  var sinon = require('sinon'),
+    expect = require('expect.js'),
+    mockuire;
+
+  mockuire = require('mockuire')(module, {
+    'js': {compile: function (src) {
+      return 'var applicationContext = require("applicationContext");\n' + src;
+    }}
+  });
+
+  describe('setup.js', function () {
+    var db = {}, ctx = {};
+
+    beforeEach(function () {
+      ctx.collectionName = sinon.stub();
+      db._collection = sinon.stub();
+      db._create = sinon.stub();
+    });
+
+    it('creates a sessions collection if it does not exist', function () {
+      ctx.collectionName.withArgs('sessions').returns('magic');
+      db._collection.returns(null);
+      mockuire('../setup', {
+        applicationContext: ctx,
+        'org/arangodb': {db: db}
+      });
+      expect(db._create.callCount).to.equal(1);
+      expect(db._create.args[0]).to.eql(['magic']);
+    });
+
+    it('does not overwrite an existing collection', function () {
+      ctx.collectionName.returns('magic');
+      db._collection.returns({});
+      mockuire('../setup', {
+        applicationContext: ctx,
+        'org/arangodb': {db: db}
+      });
+      expect(db._create.callCount).to.equal(0);
+    });
+  });
+}());
\ No newline at end of file
diff --git a/js/apps/system/users/errors.js b/js/apps/system/users/errors.js
index b8fb47e405..ed9ee667e9 100644
--- a/js/apps/system/users/errors.js
+++ b/js/apps/system/users/errors.js
@@ -2,7 +2,6 @@
 /*global require, exports */
 (function () {
   'use strict';
-
   function UserNotFound(uid) {
     this.message = 'User with user id ' + uid + ' not found.';
     var err = new Error(this.message);
diff --git a/js/apps/system/users/package.json b/js/apps/system/users/package.json
index e05d10d5ca..b0ca357fbe 100644
--- a/js/apps/system/users/package.json
+++ b/js/apps/system/users/package.json
@@ -2,11 +2,9 @@
   "private": true,
   "devDependencies": {
     "expect.js": "^0.3.1",
-    "joi": "^4.6.2",
     "mocha": "^1.21.4",
     "mockuire": "^0.1.0",
-    "sinon": "^1.10.3",
-    "underscore": "^1.6.0"
+    "sinon": "^1.10.3"
   },
   "scripts": {
     "test": "mocha --growl"