如何测试解析的参数集？

Question

I'm trying to write a basic Pester test that checks an "advanced" function for the resolved parameter set:

function Do-Stuff
{
    [CmdletBinding(DefaultParameterSetName='Set 1')]
    [OutputType([String])]

    Param
    (
        [Parameter(ParameterSetName='Set 1')] 
        [switch]
        $S1,

        [Parameter(ParameterSetName='Set 2')]
        [switch]
        $S2
    )

    $PSBoundParameters |select -ExpandProperty Keys
}

Describe Do-Stuff {
    It 'Returns "S2" when switch "S2" is set' {
        $actual = Do-Stuff -S2 
        $expexted = 'S2'
        $actual |Should Be $expexted
    }

    # How to test the resolved parameter set?
    It 'The resolved parameter set is "Set 2" when switch "S2" is set' { 
        $actual = 'What to do here?' # I'm lost ;(
        $expexted = 'Set 2'
        $actual |Should Be $expexted
    }
}

Thanx. Any advice would be highly appreciated since I'm totally new to Pester. ...not much better in posh and coding in general either :D

Answer 1

You would use the Trace-Command cmdlet for this.

The -Name parameter would be set to ParameterBinderController .

As a way to get started, try something like this (outside of pester)

Trace-Command -Name ParameterBinderController -Expression { Do-Stuff -S2 } -PSHost

The -PSHost options sends the output to the host so you can see it.

You will probably want to not use that in your Pester test, and experiment with the other listener options and methods of catching the output.

Answer 2

The following will test if you use 'Set 2' for parameter S2:

Describe Do-Stuff {
    $Command = Get-Command 'Do-Stuff'

    It 'Returns "S2" when switch "S2" is set' {
        $actual = Do-Stuff -S2 
        $expexted = 'S2'
        $actual |Should Be $expexted
    }

# How to test the resolved parameter set?
    It 'The resolved parameter set is "Set 2" when switch "S2" is set' { 
        $actual = $Command.Parameters["S2"].ParameterSets.Keys
        $expexted = 'Set 2'
        $actual |Should Be $expexted
        # when you use several sets for parameters
        $expexted -contains $actual | should Be $true
   }

}

Tracing if powershell is actually executing 'set 2', when you set it so, not a subject for pester testing imho...

Answer 3

Use as follows:

Function Main{
  [CmdletBinding(SupportsShouldProcess=$true,DefaultParameterSetName="ViewOnly")]
Param(

[Parameter(ParameterSetName="ViewOnly")]
   [switch]$ViewOnly,

[Parameter(ParameterSetName="NukeAll")]
 [switch]$NukeAll
)

Switch ($PSCmdlet.ParameterSetName){
 "NukeAll"{
NukeAll
 }#end nuke all
"ViewOnly"{
ViewOnly
}#end viewonly
  }#end Switch

Function NukeAll {
  #Do NukeAll function code here.
 }

Function ViewOnly{
  #Do ViewOnly function code here.
 }