Powershell: Switch and If on $null valued variable behaving diffrently - powershell

Question

I do not know why my switch-statemant won't evaluate the default branch:
function Test-Function {
[CmdletBinding()]param()
$stage = Get-ItemProperty -Path $REGISTRY_KEY -Name $FRUIT_VALUE -ErrorAction Ignore
if ($null -eq $stage) {
"`$stage is `$null."
#$stage = $null
}
switch ($stage) {
"apple" {"We found an apple"; break}
"pear" {"We found a pear"; break}
"orange" {"We found an orange"; break}
"peach" {"We found a peach"; break}
"banana" {"We found a banana"; break}
default {"Something else happened"; break}
}
}
Get-ItemProperty returns $null because the registry value is missing. As one would expect I get $stage is $null. as an output. But strangely the output won't display Something else happened. If I do set $stage = $null (line 7) although it's already $null I do get the desired output:
$stage is $null.
Something else happened
What am I missing?
Further minification
function Test-Function {
[CmdletBinding()]param()
$txt = (Get-ItemProperty -Path "HKLM:\SOFTWARE\does\not" -Name "exist" -ErrorAction Ignore)
if ($null -eq $txt) {
"if: `$null"
# $txt = $null
}
switch ($txt) {
"test" {"switch: TEST"}
$null {"switch: `$null"}
default {"switch: DEFAULT"}
}
}
Neither switch: $null nor switch: DEFAULT appears as output but if: $null does. How come?

Answer 1

Also, be careful with empty returns from cmdlets. Cmdlets or pipelines that have no output are treated as an empty array that does not match anything, including the default case.
$file = Get-ChildItem NonExistantFile*
switch ( $file )
{
$null { '$file is $null' }
default { "`$file is type $($file.GetType().Name)" }
}
# No matches
Taken from here