Uninstall-Module fails to uninstall even if no dependency left.

[sburbano]

Steps to reproduce

On a clean PS install, running as admin

PS C:\WINDOWS\system32> get-module PowerShellGet, PackageManagement -ListAvailable

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Binary     1.0.0.1    PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     1.0.0.1    PowerShellGet                       {Install-Module, Find-Module, Save-Module, Update-Module...}
PS C:\WINDOWS\system32> install-module PackageManagement -RequiredVersion 1.4.3 -AllowClobber
PS C:\WINDOWS\system32> install-module PowerShellGet -RequiredVersion 2.2 -AllowClobber
PS C:\WINDOWS\system32> Update-Module PowerShellGet
PS C:\WINDOWS\system32> Get-Module PackageManagement,PowerShellGet -ListAvailable

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.4.4      PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     1.4.3      PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Binary     1.0.0.1    PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     2.2.1      PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability...}
Script     2.2        PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability...}
Script     1.0.0.1    PowerShellGet                       {Install-Module, Find-Module, Save-Module, Update-Module...}

Close and reopen PS as admin

PS C:\WINDOWS\system32> Import-Module PowerShellGet -Version 2.2.1
PS C:\WINDOWS\system32> Get-Module PowerShellGet, PackageManagement

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.4.4      PackageManagement                   {Find-Package, Find-PackageProvider, Get-Package, Get-PackageProvider...}
Script     2.2.1      PowerShellGet                       {Find-Command, Find-DscResource, Find-Module, Find-RoleCapability...}

PS C:\WINDOWS\system32> Get-Module PowerShellGet, PackageManagement -ListAvailable

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.4.4      PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     1.4.3      PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Binary     1.0.0.1    PackageManagement                   {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource...}
Script     2.2.1      PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability...}
Script     2.2        PowerShellGet                       {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability...}
Script     1.0.0.1    PowerShellGet                       {Install-Module, Find-Module, Save-Module, Update-Module...}

PS C:\WINDOWS\system32> Uninstall-Module PowerShellGet -RequiredVersion 2.2
PS C:\WINDOWS\system32> Uninstall-Module PackageManagement -RequiredVersion 1.4.3
PackageManagement\Uninstall-Package : El módulo "PackageManagement" de versión "1.4.3" de la carpeta base del módulo "C:\Program
Files\WindowsPowerShell\Modules\PackageManagement\1.4.3" no se puede desinstalar debido a que uno o más módulos distintos "PowerShellGet" dependen de este módulo.
Desinstala los módulos que dependen de este antes de desinstalar el módulo "PackageManagement".
En C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\2.2.1\PSModule.psm1: 12655 Carácter: 21
+ ...        $null = PackageManagement\Uninstall-Package @PSBoundParameters
+                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (Microsoft.Power...ninstallPackage:UninstallPackage) [Uninstall-Package], Exception
    + FullyQualifiedErrorId : UnableToUninstallAsOtherModulesNeedThisModule,Uninstall-Package,Microsoft.PowerShell.PackageManagement.Cmdlets.UninstallPackage

Expected behavior

Module uninstalled, since there are no dependencies left (please note that PowerShellGet 2.2.1 depends on PackageManagement v1.4.4)

Actual behavior

Uninstall-Module throws an error and doesn't remove the module. -Force works though:

PS C:\WINDOWS\system32> Uninstall-Module PackageManagement -RequiredVersion 1.4.3 -Force
PS C:\WINDOWS\system32>

Cause of issue is in providerfunctions/Uninstall-Package.ps1 lines 92-100

            $dependentModuleScript = {
                                param ([string] $moduleName)
                                Microsoft.PowerShell.Core\Get-Module -ListAvailable |
                                Microsoft.PowerShell.Core\Where-Object {
                                    ($moduleName -ne $_.Name) -and (
                                    ($_.RequiredModules -and $_.RequiredModules.Name -contains $moduleName) -or
                                    ($_.NestedModules -and $_.NestedModules.Name -contains $moduleName))
                                }
                            }

The dependency check should be performed not only on the RequiredModules.Name, but also on RequiredModules.Version, which should be less-than-or-equal to the version of the module being uninstalled in order to be considered a dependency.

PS C:\WINDOWS\system32> (Get-Module PowerShellGet).RequiredModules

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     1.4.4      PackageManagement                   {Find-Package, Find-PackageProvider, Get-Package, Get-PackageProvider...}

Environment data

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.17763.592
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.17763.592
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

[SydneyhSmith]

@sburbano thanks for opening this issue and for doing some of the debugging work to identify where the fix needs to occur...we are currently doing a major re-write of this module so no promises on a quick fix for this issue (but we'd happily accept a PR 😄 )...thanks for all the info!