Need test to catch Pipeline-able input with missing process block

[EklipZgit]

Currently you can create functions / cmdlets with parameters with ValueFromPipeline or ValueFromPipelineByPropertyName, but if you forget the process { } block, only the last pipeline object will be processed by the cmdlet, instead of all of them, resulting in unexpected behavior that can slip through the cracks unnoticed until you pipe a batch of objects to the commandlet and realize that it only processed one of them. PSScriptAnalyzer should default to warning developers to use the process { } block when they use ValueFromPipeline or ValueFromPipelineByPropertyName attributes in a function / cmdlet.

Function Broken
{
	[CmdletBinding()]
	Param(
		[Parameter(ValueFromPipeline)]
		[int]
		$ToPrint
	)
	$ToPrint
}

Function Correct
{
	[CmdletBinding()]
	Param(
		[Parameter(ValueFromPipeline)]
		[int]
		$ToPrint
	)
	process
	{
		$ToPrint	
	}
}

1..10 | Broken
# only 10 was output. PSScriptAnalyzer ought to be catching this

1..10 | Correct
# 1 - 10 were each output, as you would expect

[bergmeister]

@rjmholt Is there a reason the Parser does not throw in this case?

[rjmholt]

Is there a reason the Parser does not throw in this case?

The syntax here is perfectly valid, so it's not a syntax error. More than that, it's not what PowerShell deems a semantic error either, since those are things that are valid syntax but can't possibly have a non-error behaviour at runtime (for example function Hi { param([void]$Str) $Str } presents a semantic error claiming to be a ParserError). Perhaps it should be in the latter cases but, because PowerShell currently supports parsing this syntax without error, it's likely the behaviour can't be changed.

Instead, we just need to write a simple rule that, when there's no process block on a ScriptBlockAst, looks for parameters marked with ValueFromPipeline.

[mattmcnabb]

I'd like to throw my hat in the ring here - please consider PR #1373 to address this issue.

[mattmcnabb]

@EklipZgit I plagiarized your example code in the help doc for this rule - hope you don't mind.

[EklipZgit]

Awesome, thanks for taking a look at this!