diff --git a/test/utility.coffee b/test/utility.coffee
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+###
+Copyright (C) 2016 Thomas Rosenau
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+  * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 'AS IS'
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+###
+
+'use strict'
+
+utility = require '../lib/utility'
+expect = require('chai').expect
+
+describe 'utility:', ->
+    describe 'deepCopy:', ->
+        it 'copies objects', ->
+            o = {}
+            copy = utility.deepCopy o
+            expect(JSON.stringify copy).to.equal JSON.stringify o
+            expect(copy).not.to.equal o
+
+            a = []
+            copy = utility.deepCopy a
+            expect(JSON.stringify copy).to.equal JSON.stringify a
+            expect(copy).not.to.equal a
+
+            o2 = {a: 1, b: 2, c: [{d: true}]}
+            copy = utility.deepCopy o2
+            expect(JSON.stringify copy).to.equal JSON.stringify o2
+            expect(copy).not.to.equal o2
+            expect(copy.c).not.to.equal o2.c
+            expect(copy.c[0]).not.to.equal o2.c[0]
+
+        it 'filters internal properties', ->
+            o = {__foo: true, bar: [{__baz: 1}, 2]}
+            copy = utility.deepCopy o
+            expect(copy.__foo).to.equal undefined
+            expect(copy.bar[0].__baz).to.equal undefined
+            expect(JSON.stringify copy).to.equal JSON.stringify {bar: [{}, 2]}
+
+    describe 'generateNextName:', ->
+        it 'generates names', ->
+            expect(utility.generateNextName 'a').to.equal 'b'
+            expect(utility.generateNextName 'b').to.equal 'c'
+            expect(utility.generateNextName 'z').to.equal 'A'
+            expect(utility.generateNextName 'A').to.equal 'B'
+            expect(utility.generateNextName 'Z').to.equal '_'
+            expect(utility.generateNextName '_').to.equal '$'
+            expect(utility.generateNextName '$').to.equal 'a0'
+            expect(utility.generateNextName 'a0').to.equal 'a1'
+            expect(utility.generateNextName 'az').to.equal 'aA'
+            expect(utility.generateNextName 'aZ').to.equal 'a_'
+            expect(utility.generateNextName 'a_').to.equal 'a$'
+            expect(utility.generateNextName 'a$').to.equal 'b0'
+            expect(utility.generateNextName '$$').to.equal 'a00'
+            expect(utility.generateNextName 'Z$$').to.equal '_00'
+            expect(utility.generateNextName '_$$').to.equal '$00'
+            expect(utility.generateNextName '$$_').to.equal '$$$'
+            expect(utility.generateNextName '$$$').to.equal 'a000'
+            expect(utility.generateNextName 'correcthorsebatterystaple').to.equal 'correcthorsebatterystaplf'