Install should implement ShouldProcess (#425)

* Install should impelement ShouldProcess

Author: anamnavi

src/code/InstallPSResource.cs

@@ -1,3 +1,4 @@
+using System.Collections.Specialized;
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 using System;
@@ -15,7 +16,7 @@ namespace Microsoft.PowerShell.PowerShellGet.Cmdlets
     /// It returns nothing.
     /// </summary>
 
-    [Cmdlet(VerbsLifecycle.Install, "PSResource", DefaultParameterSetName = "NameParameterSet", SupportsShouldProcess = true, HelpUri = "<add>")]
+    [Cmdlet(VerbsLifecycle.Install, "PSResource", DefaultParameterSetName = "NameParameterSet", SupportsShouldProcess = true)]
     public sealed
     class InstallPSResource : PSCmdlet
     {
@@ -124,6 +125,12 @@ protected override void BeginProcessing()
 
         protected override void ProcessRecord()
         {
+            if (!ShouldProcess(string.Format("package to install: '{0}'", String.Join(", ", Name))))
+            {
+                WriteVerbose(string.Format("Install operation cancelled by user for packages: {0}", String.Join(", ", Name)));
+                return;
+            }
+
             var installHelper = new InstallHelper(updatePkg: false, savePkg: false, cmdletPassedIn: this);
 
             switch (ParameterSetName)

test/InstallPSResource.Tests.ps1

@@ -226,6 +226,13 @@ Describe 'Test Install-PSResource for Module' {
         $pkg | Should -Not -BeNullOrEmpty
         $pkg.Name | Should -Be $publishModuleName
     }
+
+    It "Install module using -WhatIf, should not install the module" {
+        Install-PSResource -Name "TestModule" -WhatIf
+    
+        $res = Get-Module "TestModule" -ListAvailable
+        $res | Should -BeNullOrEmpty
+    }
 }
 
 <# Temporarily commented until -Tag is implemented for this Describe block