Changes to SqlServerDsc

- Now the helper function Restart-SqlService, after restarting the SQL Server
  service, does not return until it can connect to the SQL Server instance, and
  the instance returns status 'Online' (issue dsccommunity#1008).
  If it fails to connect within the timeout period (defaults to 120 seconds) it
  throws an error.

CHANGELOG.md

@@ -41,6 +41,11 @@
   - Updated the security token for AppVeyor status badge in README.md. When we
     renamed the repository the security token was changed
     ([issue #1012](https://github.com/PowerShell/SqlServerDsc/issues/1012)).
+  - Now the helper function Restart-SqlService, after restarting the SQL Server
+    service, does not return until it can connect to the SQL Server instance, and
+    the instance returns status 'Online' ([issue #1008](https://github.com/PowerShell/SqlServerDsc/issues/1008)).
+    If it fails to connect within the timeout period (defaults to 120 seconds) it
+    throws an error.
   - Fixed typo in comment-base help for helper function Test-AvailabilityReplicaSeedingModeAutomatic.
   - Style cleanup in helper function tests.
 - Changes to SqlAG
@@ -123,6 +128,11 @@
     name is correctly returned as a string ([issue #982](https://github.com/PowerShell/SqlServerDsc/issues/982)).
   - Added integration tests ([issue #980](https://github.com/PowerShell/SqlServerDsc/issues/980)).
   - Minor code style cleanup.
+  - The timing issue that the resource returned before SQL Server service was
+    actually restarted has been solved by a change in the helper function
+    Restart-SqlService ([issue #1008](https://github.com/PowerShell/SqlServerDsc/issues/1008)).
+    Now Restart-SqlService waits for the instance to return status 'Online' or
+    throws an error saying it failed to connect within the timeout period.
 - Changes to SqlSetup
   - Added parameter `ASServerMode` to support installing Analysis Services in
     Multidimensional mode, Tabular mode and PowerPivot mode

SqlServerDscHelper.psm1

@@ -842,6 +842,61 @@ function Restart-SqlService
             $_ | Start-Service
         }
     }
+
+    Write-Verbose -Message ($script:localizedData.WaitingInstanceTimeout -f $SQLServer, $SQLInstanceName, $Timeout) -Verbose
+
+    $startJobScriptBlock = {
+        param
+        (
+            [Parameter()]
+            [System.String]
+            $ServerName,
+
+            [Parameter()]
+            [System.String]
+            $InstanceName,
+
+            [Parameter()]
+            [System.String]
+            $ScriptRoot
+        )
+
+        Import-Module -Name (Join-Path -Path $ScriptRoot -ChildPath 'SqlServerDscHelper.psm1')
+
+        do
+        {
+            # This call, if it fails, will take between ~9-10 seconds to return.
+            $serverObject = Connect-SQL -SQLServer $ServerName -SQLInstanceName $InstanceName -ErrorAction SilentlyContinue
+            if ($serverObject.Status -ne 'Online')
+            {
+                # Waiting 2 seconds to not hammer the SQL Server instance.
+                Start-Sleep -Seconds 2
+            }
+        } until ($serverObject.Status -eq 'Online')
+    }
+
+    $startJobResult = Start-Job -ScriptBlock $startJobScriptBlock -ArgumentList @(
+        $SQLServer
+        $SQLInstanceName
+        $PSScriptRoot
+    )
+
+    Wait-Job -Job $startJobResult -Timeout $Timeout
+
+    if ($startJobResult.JobStateInfo.State -ne 'Completed')
+    {
+        # Output any verbose messages and error messages.
+        Receive-Job -Job $startJobResult
+
+        # Make sure the job is stopped.
+        Stop-Job -Job $startJobResult
+
+        $errorMessage = $script:localizedData.FailedToConnectToInstanceTimeout -f $SQLServer, $SQLInstanceName, $Timeout
+        New-InvalidOperationException -Message $errorMessage
+    }
+
+    # Make sure the job is removed.
+    Remove-Job -Job $startJobResult -Force
 }
 
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