[Bug] PowerShell Hashtables and duplicate keys with Import-CliXml

HashtableDuplicateKey.Tests.ps1

#Requires -Module Pester
#Requires -Version 3.0

# see http://d-fens.ch/2015/06/28/bug-powershell-import-clixml-incorrectly-creates-hashtables-with-duplicate-keys/ for further explanation

$here = Split-Path -Parent $MyInvocation.MyCommand.Path
$ImportCliXmlDuplicateKeys = "{0}.xml" -f $MyInvocation.MyCommand.Name.Replace('.Tests.ps1', '');

Describe -Tags "Test-ImportCliXml" "Test-ImportCliXml" {

    $ImportCliXmlDuplicateKeysPathAndFileName = Join-Path -Path $here -ChildPath $ImportCliXmlDuplicateKeys;

    Context "Test-ImportCliXmlWithDuplicateKeys" {
    
        It 'ShouldThrow-OnImportWithDuplicateKeys' {
            { Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName } | Should Throw;
        }
        It 'ShouldNotBe-TypeHashtable' {
            $hashtable = Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName;
            $hashtable -is [hashtable] | Should Not Be $True;
        }
        It 'ShouldNot-Contain2Keys' {
            $hashtable = Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName;
            $hashtable.Count | Should Not Be 2;
        }
        It 'ShouldNotThrow-ExceptionWhenAdding' {
            $hashtable = Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName;
            $hashtableTemp = @{};
            {
                foreach($i in $hashtable.GetEnumerator())
                {
                    $hashtableTemp.Add($i.Name, $i.Value);
                }
            } | Should Not Throw;
        }            
        It 'ShouldBe-TrueAndFindKey' {
            $hashtable = Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName;
            foreach($i in $hashtable.Keys)
            {
                $keyName = '{0}' -f $i;
                break;
            }
            $hashtable.ContainsKey($keyName) | Should Be $true;
        }            
        It 'ShouldBe-TrueAndFindValues' {
            $hashtable = Import-CliXml $ImportCliXmlDuplicateKeysPathAndFileName;
            $hashtable.ContainsValue('some other arbitrary value') | Should Be $true;
            $hashtable.ContainsValue('arbitrary value') | Should Be $true;
        }            
    }
}

 #
 # Copyright 2015 Ronald Rink, d-fens GmbH
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 # http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #

HashtableDuplicateKey.xml

<Objs Version="1.1.0.1" xmlns="http://schemas.microsoft.com/powershell/2004/04">
  <Obj RefId="0">
    <TN RefId="0">
      <T>System.Collections.Hashtable</T>
      <T>System.Object</T>
    </TN>
    <DCT>
      <En>
        <S N="Key">DuplicateKey</S>
        <S N="Value">arbitrary value</S>
      </En>
      <En>
        <S N="Key">DuplicateKey</S>
        <S N="Value">some other arbitrary value</S>
      </En>
    </DCT>
  </Obj>
</Objs>