PesterExtensions

0.7.1

Public/Mock-EnvironmentVariable.ps1

function Mock-EnvironmentVariable {
    param (
        [parameter(Mandatory = $true, Position = 0)]
        [string]
        $Variable,
        
        [Parameter(Mandatory = $false)]
        [string]
        $Value,

        [Parameter(Mandatory = $true, Position = 1)]
        [ScriptBlock]
        $Fixture
    )
    $EnvironmentVariable = "env:${Variable}"
    if (Test-Path -Path $EnvironmentVariable) {
        $OriginalValue = (Get-ChildItem -Path $EnvironmentVariable).Value
        if ($value) {
            Set-Item -Path $EnvironmentVariable -Value $Value
        }
    }
    else {
        New-Item -Path $EnvironmentVariable -Value $Value | Out-Null
    }
    try {
        Invoke-Command -ScriptBlock $Fixture
    }

    catch {
        throw $_
    }

    finally {
        if ($OriginalValue) {
            Set-Item -Path $EnvironmentVariable -Value $OriginalValue
        }
        elseif (Test-Path -Path $EnvironmentVariable) {
            Remove-Item `
                -Path $EnvironmentVariable `
                -Recurse `
                -Force `
                -ErrorAction Stop
        }
    }

    <#
    .PARAMETER Variable
    The environment variable to mock.
 
    .PARAMETER Value
    The initial value of the mocked environment variable.
 
    .PARAMETER Fixture
    The code to be executed.
    #>
}