Pester testing more advanced powershell scripts

Question

I've been using Pester for some time now to write (simple) tests for our powershell scripts, but naturally the further I get the more difficult the scripts get. I'm not a developer (just an automation QA) and therefore cannot really start changes the existing code, but I do need to write unit tests for them.

In the following script I have I'm running into 2 problems:

The function starts by running another .ps1 file using the call operator - This other script can only be run as an administrator and does some pre-deployment checks. Now I do not want to unit test this external script so I need a way to mock or bypass the & $PSScriptRoot\\PreReqCheck.ps1 call. I thought simply mocking it would be nice but & is reserved for future use and it is advising to wrap in quotes as a string, which does not really seem to work.

The second (but I think this might be eeasier to solve) is the following:

After PreReqCheck has been run certain variables will be filled ($computerName, $masterNodes, $dataNodes) and continues with an If/Elseif/Elseif statement which depending on the variables sets, gets and starts a service. Like this piece of code:

If ($computerName = "X")
{
    $masterNodes = @("1","2","3")
    $dataNodes = @("01","02","03")
}
Elseif ($computerName = "Y")
{
    $masterNodes = @("1","2","3")
    $dataNodes = @("01","02","03")

}
Elseif ($computerName = "Z")
{
    $masterNodes = @("1","2","3")
    $dataNodes = @("01","02","03")
}

forEach ($masterNode in $masterNodes)
{
    Does something
}

forEach ($dataNode in $dataNodes)
{
    Does something
}

My question about this is. How can I best create a test where I can state which variables to use? I have tried something like this:

Describe "ReconfigureMainCluster" {
Context "test" {

        Mock Set-Service
        Mock Get-service
        #Mock Write-Host
        Mock Start-Service
        $computerName = "X"

        It "checks something" {
            ReconfigureMainCluster
            Assert-MockCalled 'Set-Service' -Exactly 12
            Assert-MockCalled 'Write-Host' -Exactly 22
            Assert-MockCalled 'Get-Service' -Exactly 6
        }

            It "checks computername"{
                $computerName | Should be "X" 
   }
}

}

This passes, but when I write a similar test for computerName Y the variable $computerName stays X (I can see that because of commenting out Mock Write-Host and the same text is stated twice.

I think I will need to define the variables somewhere but not sure where or how...

Answer 1

For the first part (the call operator) changing it to start-process seemed to work

For the second part changing the original powershell script part:

$computerName = "Y" to $computerName -eq "Y"

Seemed to work as well.

Not sure if this is the best way to do it though.