Koans/Katas/ProcessingStrings.Koans.ps1

using module PSKoans
[Koan(Position = 150)]
param()
<#
    Kata: Processing Strings

    Below is a list containing comma separated data about Microsoft's stock prices
    during March of 2012. Without modifying the list, programatically find the day
    with the greatest variance between the opening and closing price.

    The following operations may be of use:

    [double] $value # Casts (converts) the value into numerical data
    $String -split ',' # Creates an array by splitting the string

    Be sure to review AboutStrings and AboutArrays if you need to!
#>

Describe "The Stock Challenge" {
    BeforeAll {
        $StockData = @(
            "Date,Open,High,Low,Close,Volume,Adj Close"
            "2012-03-30,32.40,32.41,32.04,32.26,31749400,32.26"
            "2012-03-29,32.06,32.19,31.81,32.12,37038500,32.12"
            "2012-03-28,32.52,32.70,32.04,32.19,41344800,32.19"
            "2012-03-27,32.65,32.70,32.40,32.52,36274900,32.52"
            "2012-03-26,32.19,32.61,32.15,32.59,36758300,32.59"
            "2012-03-23,32.10,32.11,31.72,32.01,35912200,32.01"
            "2012-03-22,31.81,32.09,31.79,32.00,31749500,32.00"
            "2012-03-21,31.96,32.15,31.82,31.91,37928600,31.91"
            "2012-03-20,32.10,32.15,31.74,31.99,41566800,31.99"
            "2012-03-19,32.54,32.61,32.15,32.20,44789200,32.20"
            "2012-03-16,32.91,32.95,32.50,32.60,65626400,32.60"
            "2012-03-15,32.79,32.94,32.58,32.85,49068300,32.85"
            "2012-03-14,32.53,32.88,32.49,32.77,41986900,32.77"
            "2012-03-13,32.24,32.69,32.15,32.67,48951700,32.67"
            "2012-03-12,31.97,32.20,31.82,32.04,34073600,32.04"
            "2012-03-09,32.10,32.16,31.92,31.99,34628400,31.99"
            "2012-03-08,32.04,32.21,31.90,32.01,36747400,32.01"
            "2012-03-07,31.67,31.92,31.53,31.84,34340400,31.84"
            "2012-03-06,31.54,31.98,31.49,31.56,51932900,31.56"
            "2012-03-05,32.01,32.05,31.62,31.80,45240000,31.80"
            "2012-03-02,32.31,32.44,32.00,32.08,47314200,32.08"
            "2012-03-01,31.93,32.39,31.85,32.29,77344100,32.29"
            "2012-02-29,31.89,32.00,31.61,31.74,59323600,31.74"
        )

        <#
            For the purposes of the exercise, use of cmdlets will be disabled for the solving function.
            You're on your own here, use your knowledge of arrays and string operators to get you to
            the finish line!
        #>


        $Verification = {
            [string[]]$AllowedCommands = @()
            [string[]]$AllowedVariables = @("*")
            $Function = Get-Item -Path 'Function:Get-GreatestVarianceDate'
            $Function.ScriptBlock.CheckRestrictedLanguage($AllowedCommands, $AllowedVariables, $false)
        }

        function Get-GreatestVarianceDate {
            param([string[]]$Data)

            # Add the solution code here!

        }
    }

    <#
        Feel free to add extra It/Should tests here to write tests for yourself and
        experiment along the way!
    #>


    It 'should not use any cmdlets or external commands' {
        $Verification | Should -Not -Throw -Because "You must not rely on the power of others here."
    }

    It 'should determine the correct answer' {
        Get-GreatestVarianceDate -Data $StockData | Should -Be "2012-03-13"
    }
}