Unassigned variable rule does not consider += operator to be an assignment

[triplec110h]

System Details

• Operating system name and version:
• VS Code version: 1.12.2
• PowerShell extension version: 1.1.0
• Output from $PSVersionTable:

Copy / paste the below commands into the PowerShell Integrated Terminal, and paste the output here

code -v
1.12.2
19222cdc84ce72202478ba1cec5cb557b71163de

$pseditor.EditorServicesVersion
Major  Minor  Build  Revision
-----  -----  -----  --------
1      1      0      0

code --list-extensions --show-versions
emmanuelbeziat.vscode-great-icons@2.1.4
ms-vscode.PowerShell@1.1.0

$PSVersionTable
Name                           Value
----                           -----
PSVersion                      5.1.14393.1066
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.1066
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

Issue Description

I am experiencing a problem with...
PSES says variable is assigned but never used. It is used just below - see screenshot

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[daviwil]

Hey @kapilmb, is there a bug tracking this already? Seems like I've seen one but I can't find it.

[kapilmb]

This is a known bug with the PSUseDeclaredVarsMoreThanAssignments rule. It is been tracked at PowerShell/PSScriptAnalyzer#636.

[daviwil]

Thanks! I'll keep this bug open to track the issue for the next update, but the fix will come as a part of the next PSScriptAnalyzer update.

[johlju]

Maybe you are thinking of #772? I closed it since it was by design (how Pester script works). But yesterday I saw the same problem in a normal PowerShell module when the variable was used in a script block, but assigned outside of the script block. Haven't had the time to submit an issue for that yet.

[daviwil]

Yeah! That's the one :)

[kapilmb]

On the surface #772 looks similar to this case but they are different. In #772, there is no way for PSSA to know if $testParmeters is in the same scope as that of the following it statements, as PSSA doesn't know what Pester does with those script blocks. But in this case PSSA clearly has more knowledge about the SIDMappingOutput variable.

[johlju]

I got another example of the problem @triplec110h describing.

Only one of the variable $result is saying 'is assigned but never used'.