Alright powershell people. Explain this behaviour to me if you would.

powershell.exe

PS> help .\test.ps1
test.ps1 [-FirstParam] <Object> [-SecondParam] <Object> [<CommonParameters>]

PS> .\test.ps1 -fi<tab>
# Nothing happens at all.

PS> .\test.ps1
.\test.ps1 : The script 'test.ps1' cannot be run because the following snap-ins that are specified by the "#requires"
statements of the script are missing: VMware.VimAutomation.Core.
...

PS> Add-PSSnapin VMware.Vimautomation.Core

PS> .\test.ps1 -fi<tab>
# Completes to:
PS> .\test.ps1 -FirstParam

test.ps1

#Requires -PSSnapin VMware.VimAutomation.Core
Param (
    [Parameter(Mandatory = $True)]
    $FirstParam,

    [Parameter(Mandatory = $True)]
    $SecondParam
)

Write-Host "Running."