removing HyperV change to unblock Patch Tuesday

Revert "removed Enable-HyperV from provisioning steps"

This reverts commit cc267b4.

[#173045518](https://www.pivotaltracker.com/story/show/173045518)
As a platform operator I should be able to use Windows stemcells with Hyper-V disabled

Co-authored-by: Flora Gallina-Jones <[email protected]>

Author: Austina Lin

stemcell-automation/AutomationHelpers.Tests.ps1

@@ -125,6 +125,43 @@ Describe "InstallCFFeatures" {
     }
 }
 
+Describe "Enable-HyperV" {
+    It "executes the Enable-Hyper-V powershell cmdlet when the os version is 2019" {
+        Mock Enable-Hyper-V { }
+        Mock Write-Log { }
+        $osVersion2019 = "10.0.17763.2761"
+        Mock Get-OSVersionString { $osVersion2019 }
+
+        { Enable-HyperV } | Should -Not -Throw
+
+        Assert-MockCalled Enable-Hyper-V -Times 1 -Scope It
+        Assert-MockCalled Write-Log -Times 1 -Scope It -ParameterFilter { $Message -eq "Successfully enabled HyperV" }
+    }
+
+    It "does not execute the Enable-Hyper-V powershell cmdlet when the os version is not 2019" {
+        Mock Enable-Hyper-V { }
+        Mock Write-Log { }
+        $osVersion1803 = "10.0.17134.2761"
+        Mock Get-OSVersionString { $osVersion1803 }
+
+        { Enable-HyperV } | Should -Not -Throw
+
+        Assert-MockCalled Enable-Hyper-V -Times 0 -Scope It
+        Assert-MockCalled Write-Log -Times 1 -Scope It -ParameterFilter { $Message -eq "Did not enable HyperV because OS Version is not 2019" }
+    }
+
+    It "fails gracefully when enabling Hyper-V" {
+        Mock Enable-Hyper-V { throw "unable to comply" }
+        Mock Write-Log { }
+        $osVersion2019 = "10.0.17763.2761"
+        Mock Get-OSVersionString { $osVersion2019 }
+
+        { Enable-HyperV } | Should -Throw "unable to comply"
+
+        Assert-MockCalled Write-Log -Times 1 -Scope It -ParameterFilter { $Message -eq "unable to comply" }
+        Assert-MockCalled Write-Log -Times 1 -Scope It -ParameterFilter { $Message -eq "Failed to enable HyperV. See 'c:\provision\log.log' for more info." }
+    }
+}
 
 Describe "InstallCFCell" {
     It "executes the Protect-CFCell powershell cmdlet" {

stemcell-automation/AutomationHelpers.ps1

@@ -71,6 +71,28 @@ function InstallCFFeatures
     }
 }
 
+function Enable-HyperV
+{
+    try
+    {
+        $osVersion2019Regex = "10\.0\.17763\..+"
+        $osVersion = Get-OSVersionString
+        if ($osVersion -match $osVersion2019Regex) {
+            Enable-Hyper-V
+            Write-Log "Successfully enabled HyperV"
+        }
+        else {
+            Write-Log "Did not enable HyperV because OS Version is not 2019"
+        }
+
+    }
+    catch [Exception]
+    {
+        Write-Log $_.Exception.Message
+        Write-Log "Failed to enable HyperV. See 'c:\provision\log.log' for more info."
+        throw $_.Exception
+    }
+}
 
 function InstallCFCell
 {

stemcell-automation/ProvisionVM.Tests.ps1

@@ -12,6 +12,7 @@ Describe "ProvisionVM" {
         Mock Enable-SSHD { $provisionerCalls.Add("Enable-SSHD") }
         Mock Install-SecurityPoliciesAndRegistries { $provisionerCalls.Add("Install-SecurityPoliciesAndRegistries") }
         Mock Extract-LGPO { $provisionerCalls.Add("Extract-LGPO") }
+        Mock Enable-HyperV { $provisionerCalls.Add("Enable-HyperV") }
         Mock Install-WUCerts { $provisionerCalls.Add("Install-WUCerts") }
         Mock Create-VersionFile { $provisionerCalls.Add("Create-VersionFile") }
 
@@ -35,6 +36,11 @@ Describe "ProvisionVM" {
 
         Assert-MockCalled -CommandName InstallCFFeatures
     }
+    It "enables Hyper-V when possible" {
+        ProvisionVM
+
+        Assert-MockCalled -CommandName Enable-HyperV
+    }
 
     It "copy PSModules is the first provisioner called" {
         ProvisionVM

stemcell-automation/ProvisionVM.ps1

@@ -13,7 +13,7 @@ function ProvisionVM() {
     Install-SecurityPoliciesAndRegistries
     Enable-SSHD
     InstallCFFeatures
-
+    Enable-HyperV
     try
     {
         Install-WUCerts