Update GitHubRepositories Tests and Refactor Get-GitHubRepository Function (#233)

Updates the Pester tests for the `GitHubRepositories` module to increase the code coverage.

This also:
  * Refactors `Get-GithubRepository` to remove a code path that could never be taken
  * Adds a `ValidateSet` to the `Affiliation` parameter of the `Get-GitHubRepository` function
  * Fixes the Comment Based Help descriptions for the `Get-GitHubRepositoryCollaborator` and `Move-GitHubRepositoryOwnership`

Author: X-Guardian

GitHubRepositories.ps1

@@ -658,8 +658,10 @@ filter Get-GitHubRepository
         SupportsShouldProcess,
         DefaultParameterSetName='AuthenticatedUser')]
     [OutputType({$script:GitHubRepositoryTypeName})]
-    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSShouldProcess", "", Justification="Methods called within here make use of PSShouldProcess, and the switch is passed on to them inherently.")]
-    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSReviewUnusedParameter", "", Justification="One or more parameters (like NoStatus) are only referenced by helper methods which get access to it from the stack via Get-Variable -Scope 1.")]
+    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSShouldProcess", "",
+        Justification="Methods called within here make use of PSShouldProcess, and the switch is passed on to them inherently.")]
+    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSReviewUnusedParameter", "",
+        Justification="One or more parameters (like NoStatus) are only referenced by helper methods which get access to it from the stack via Get-Variable -Scope 1.")]
     param(
         [Parameter(
             ValueFromPipelineByPropertyName,
@@ -687,6 +689,7 @@ filter Get-GitHubRepository
         [string] $Visibility,
 
         [Parameter(ParameterSetName='AuthenticatedUser')]
+        [ValidateSet('Owner', 'Collaborator', 'OrganizationMember')]
         [string[]] $Affiliation,
 
         [Parameter(ParameterSetName='AuthenticatedUser')]
@@ -736,11 +739,11 @@ filter Get-GitHubRepository
     $description = [String]::Empty
     switch ($PSCmdlet.ParameterSetName)
     {
-        { ('ElementsOrUser', 'Uri') -contains $_ } {
+        'ElementsOrUser' {
             # This is a little tricky.  Ideally we'd have two separate ParameterSets (Elements, User),
             # however PowerShell would be unable to disambiguate between the two, so unfortunately
             # we need to do some additional work here.  And because fallthru doesn't appear to be
-            # working right, we're combining both of those, along with Uri.
+            # working right, we're combining both of those.
 
             if ([String]::IsNullOrWhiteSpace($OwnerName))
             {
@@ -750,37 +753,24 @@ filter Get-GitHubRepository
             }
             elseif ([String]::IsNullOrWhiteSpace($RepositoryName))
             {
-                if ($PSCmdlet.ParameterSetName -eq 'ElementsOrUser')
-                {
-                    $telemetryProperties['UsageType'] = 'User'
-                    $telemetryProperties['OwnerName'] = Get-PiiSafeString -PlainText $OwnerName
+                $telemetryProperties['UsageType'] = 'User'
+                $telemetryProperties['OwnerName'] = Get-PiiSafeString -PlainText $OwnerName
 
-                    $uriFragment = "users/$OwnerName/repos"
-                    $description = "Getting repos for $OwnerName"
-                }
-                else
-                {
-                    $message = 'RepositoryName could not be determined.'
-                    Write-Log -Message $message -Level Error
-                    throw $message
-                }
+                $uriFragment = "users/$OwnerName/repos"
+                $description = "Getting repos for $OwnerName"
             }
             else
             {
-                if ($PSCmdlet.ParameterSetName -eq 'ElementsOrUser')
+                if ($PSBoundParameters.ContainsKey('Type') -or
+                    $PSBoundParameters.ContainsKey('Sort') -or
+                    $PSBoundParameters.ContainsKey('Direction'))
                 {
-                    $telemetryProperties['UsageType'] = 'Elements'
-
-                    if ($PSBoundParameters.ContainsKey('Type') -or
-                        $PSBoundParameters.ContainsKey('Sort') -or
-                        $PSBoundParameters.ContainsKey('Direction'))
-                    {
-                        $message = 'Unable to specify -Type, -Sort and/or -Direction when retrieving a specific repository.'
-                        Write-Log -Message $message -Level Error
-                        throw $message
-                    }
+                    $message = 'Unable to specify -Type, -Sort and/or -Direction when retrieving a specific repository.'
+                    Write-Log -Message $message -Level Error
+                    throw $message
                 }
 
+                $telemetryProperties['UsageType'] = 'Elements'
                 $telemetryProperties['OwnerName'] = Get-PiiSafeString -PlainText $OwnerName
                 $telemetryProperties['RepositoryName'] = Get-PiiSafeString -PlainText $RepositoryName
 
@@ -791,20 +781,30 @@ filter Get-GitHubRepository
             break
         }
 
-        'Organization' {
-            $telemetryProperties['OrganizationName'] = Get-PiiSafeString -PlainText $OrganizationName
+        'Uri' {
+            if ($PSBoundParameters.ContainsKey('Type') -or
+                $PSBoundParameters.ContainsKey('Sort') -or
+                $PSBoundParameters.ContainsKey('Direction'))
+            {
+                $message = 'Unable to specify -Type, -Sort and/or -Direction when retrieving a specific repository.'
+                Write-Log -Message $message -Level Error
+                throw $message
+            }
 
-            $uriFragment = "orgs/$OrganizationName/repos"
-            $description = "Getting repos for $OrganizationName"
+            $telemetryProperties['OwnerName'] = Get-PiiSafeString -PlainText $OwnerName
+            $telemetryProperties['RepositoryName'] = Get-PiiSafeString -PlainText $RepositoryName
+
+            $uriFragment = "repos/$OwnerName/$RepositoryName"
+            $description = "Getting $OwnerName/$RepositoryName"
 
             break
         }
 
-        'User' {
-            $telemetryProperties['OwnerName'] = Get-PiiSafeString -PlainText $OwnerName
+        'Organization' {
+            $telemetryProperties['OrganizationName'] = Get-PiiSafeString -PlainText $OrganizationName
 
-            $uriFragment = "users/$OwnerName/repos"
-            $description = "Getting repos for $OwnerName"
+            $uriFragment = "orgs/$OrganizationName/repos"
+            $description = "Getting repos for $OrganizationName"
 
             break
         }
@@ -857,7 +857,18 @@ filter Get-GitHubRepository
     if ($PSBoundParameters.ContainsKey('Direction')) { $getParams += "direction=$($directionConverter[$Direction])" }
     if ($PSBoundParameters.ContainsKey('Affiliation') -and $Affiliation.Count -gt 0)
     {
-        $getParams += "affiliation=$($Affiliation -join ',')"
+        $affiliationMap = @{
+            Owner = 'owner'
+            Collaborator = 'collaborator'
+            OrganizationMember = 'organization_member'
+        }
+        $affiliationParam = @()
+
+        foreach ($member in $Affiliation)
+        {
+            $affiliationParam += $affiliationMap[$member]
+        }
+        $getParams += "affiliation=$($affiliationParam -join ',')"
     }
     if ($PSBoundParameters.ContainsKey('Since')) { $getParams += "since=$Since" }
 
@@ -1602,8 +1613,12 @@ filter Get-GitHubRepositoryContributor
     .EXAMPLE
         Get-GitHubRepositoryContributor -OwnerName microsoft -RepositoryName PowerShellForGitHub
 
+        Gets a list of contributors for the PowerShellForGithub repository.
+
     .EXAMPLE
         Get-GitHubRepositoryContributor -Uri 'https://github.com/PowerShell/PowerShellForGitHub' -IncludeStatistics
+
+        Gets a list of contributors for the PowerShellForGithub repository including statistics.
 #>
     [CmdletBinding(
         SupportsShouldProcess,
@@ -1691,10 +1706,10 @@ filter Get-GitHubRepositoryCollaborator
 {
 <#
     .SYNOPSIS
-        Retrieve list of contributors for a given repository.
+        Retrieve list of collaborators for a given repository.
 
     .DESCRIPTION
-        Retrieve list of contributors for a given repository.
+        Retrieve list of collaborators for a given repository.
 
         The Git repo for this module can be found here: http://aka.ms/PowerShellForGitHub
 
@@ -1749,8 +1764,12 @@ filter Get-GitHubRepositoryCollaborator
     .EXAMPLE
         Get-GitHubRepositoryCollaborator -OwnerName microsoft -RepositoryName PowerShellForGitHub
 
+        Gets a list of collaborators for the PowerShellForGithub repository.
+
     .EXAMPLE
         Get-GitHubRepositoryCollaborator -Uri 'https://github.com/PowerShell/PowerShellForGitHub'
+
+        Gets a list of collaborators for the PowerShellForGithub repository.
 #>
     [CmdletBinding(
         SupportsShouldProcess,
@@ -2027,10 +2046,10 @@ filter Move-GitHubRepositoryOwnership
 {
 <#
     .SYNOPSIS
-        Creates a new repository on GitHub.
+        Changes the ownership of a repository on GitHub.
 
     .DESCRIPTION
-        Creates a new repository on GitHub.
+        Changes the ownership of a repository on GitHub.
 
         The Git repo for this module can be found here: http://aka.ms/PowerShellForGitHub