Make PowerShell Core enumerate COM collections (#4553)

Make PowerShell Core enumerate COM collections

test/powershell/engine/COM/COM.Basic.Tests.ps1

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+
+try {
+    $defaultParamValues = $PSdefaultParameterValues.Clone()
+    $PSDefaultParameterValues["it:skip"] = ![System.Management.Automation.Platform]::IsWindowsDesktop
+
+    Describe 'Basic COM Tests' -Tags "CI" {
+        BeforeAll {
+            $null = New-Item -Path $TESTDRIVE/file1 -ItemType File
+            $null = New-Item -Path $TESTDRIVE/file2 -ItemType File
+            $null = New-Item -Path $TESTDRIVE/file3 -ItemType File
+        }
+
+        It "Should enumerate files from a folder" {
+            $shell = New-Object -ComObject "Shell.Application"
+            $folder = $shell.Namespace("$TESTDRIVE")
+            $items = $folder.Items()
+
+            ## $items is a collection of all items belong to the folder, and it should be enumerated.
+            $items | Measure-Object | ForEach-Object Count | Should Be $items.Count
+        }
+
+        It "Should enumerate IEnumVariant interface object without exception" {
+            $shell = New-Object -ComObject "Shell.Application"
+            $folder = $shell.Namespace("$TESTDRIVE")
+            $items = $folder.Items()
+
+            ## $enumVariant is an IEnumVariant interface of all items belong to the folder, and it should be enumerated.
+            $enumVariant = $items._NewEnum()
+            $enumVariant | Measure-Object | ForEach-Object Count | Should Be $items.Count
+        }
+
+        It "Should enumerate drives" {
+            $fileSystem = New-Object -ComObject scripting.filesystemobject
+            $drives = $fileSystem.Drives
+
+            ## $drives is a read-only collection of all available drives, and it should be enumerated.
+            $drives | Measure-Object | ForEach-Object Count | Should Be $drives.Count
+            ## $element should be the first drive from the enumeration. It shouldn't be the same as $drives,
+            ## but it should be the same as '$drives.Item($element.DriveLetter)'
+            $element = $drives | Select-Object -First 1
+            [System.Object]::ReferenceEquals($element, $drives) | Should Be $false
+            $element | Should Be $drives.Item($element.DriveLetter)
+        }
+    }
+
+} finally {
+    $global:PSdefaultParameterValues = $defaultParamValues
+}