fix: bootstrap NuGet lazily only when a Nuget/PSGalleryNuget dep is used

PSDepend/PSDepend.psm1

@@ -16,7 +16,7 @@
         }
     }
 
-#Get nuget dependecy file if we don't have it
+#Read PSDepend.Config path variables
     Get-Content $ModuleRoot\PSDepend.Config |
         Where-Object {$_ -and $_ -notmatch "^\s*#"} |
         Foreach-Object {
@@ -27,8 +27,5 @@
             $Value = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($Value)
             Set-Variable -Name $Name -Value $Value
         }
-    if(Test-PlatformSupport -Support 'windows','core') {
-        BootStrap-Nuget -NugetPath $NuGetPath
-    }
 
 Export-ModuleMember -Function $Public.Basename

PSDepend/PSDependScripts/Nuget.ps1

@@ -109,7 +109,15 @@ param(
 
 if(-not (Get-Command Nuget -ErrorAction SilentlyContinue))
 {
-    Write-Error "Nuget requires Nuget.exe.  Ensure this is in your path, or explicitly specified in $ModuleRoot\PSDepend.Config's NugetPath.  Skipping [$DependencyName]"
+    if(Test-PlatformSupport -Type 'Nuget' -Support 'windows','core')
+    {
+        BootStrap-Nuget -NugetPath $NuGetPath
+    }
+    if(-not (Get-Command Nuget -ErrorAction SilentlyContinue))
+    {
+        Write-Error "Nuget requires Nuget.exe.  Ensure this is in your path, or explicitly specified in $ModuleRoot\PSDepend.Config's NugetPath.  Skipping [$DependencyName]"
+        return
+    }
 }
 
 Write-Verbose -Message "Getting dependency [$DependencyName] from Nuget source [$Source]"

PSDepend/PSDependScripts/PSGalleryNuget.ps1

@@ -97,7 +97,15 @@ param(
 
 if(-not (Get-Command Nuget -ErrorAction SilentlyContinue))
 {
-    Write-Error "PSGalleryNuget requires Nuget.exe.  Ensure this is in your path, or explicitly specified in $ModuleRoot\PSDepend.Config's NugetPath.  Skipping [$DependencyName]"
+    if(Test-PlatformSupport -Type 'PSGalleryNuget' -Support 'windows','core')
+    {
+        BootStrap-Nuget -NugetPath $NuGetPath
+    }
+    if(-not (Get-Command Nuget -ErrorAction SilentlyContinue))
+    {
+        Write-Error "PSGalleryNuget requires Nuget.exe.  Ensure this is in your path, or explicitly specified in $ModuleRoot\PSDepend.Config's NugetPath.  Skipping [$DependencyName]"
+        return
+    }
 }
 
 Write-Verbose -Message "Getting dependency [$name] from Nuget source [$Source]"

Tests/Nuget.Type.Tests.ps1

@@ -52,4 +52,44 @@ Describe 'Nuget script' {
             $Arguments -contains '-version' -and $Arguments -contains '12.0.2'
         }
     }
+
+    Context 'NuGet bootstrap' {
+        BeforeAll {
+            InModuleScope PSDepend {
+                Mock Get-Command { $null } -ParameterFilter { $Name -eq 'Nuget' }
+                Mock BootStrap-Nuget { }
+                Mock Test-PlatformSupport { $true }
+            }
+        }
+
+        It 'Calls BootStrap-Nuget when nuget.exe is missing on a supported platform' {
+            $targetDir = (New-Item 'TestDrive:/nuget-bootstrap' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'Newtonsoft.Json' -DependencyType 'Nuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName BootStrap-Nuget -ModuleName PSDepend -Times 1
+        }
+
+        It 'Does not invoke nuget install when nuget.exe is still missing after bootstrap' {
+            $targetDir = (New-Item 'TestDrive:/nuget-bootstrap-fail' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'Newtonsoft.Json' -DependencyType 'Nuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName Invoke-ExternalCommand -ModuleName PSDepend -Times 0
+        }
+
+        It 'Does not call BootStrap-Nuget on an unsupported platform' {
+            InModuleScope PSDepend {
+                Mock Test-PlatformSupport { $false }
+            }
+            $targetDir = (New-Item 'TestDrive:/nuget-bootstrap-noplatform' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'Newtonsoft.Json' -DependencyType 'Nuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName BootStrap-Nuget -ModuleName PSDepend -Times 0
+        }
+    }
 }

Tests/PSGalleryNuget.Type.Tests.ps1

@@ -51,4 +51,44 @@ Describe 'PSGalleryNuget script' {
         }
         Should -Invoke -CommandName Import-PSDependModule -ModuleName PSDepend -Times 1
     }
+
+    Context 'NuGet bootstrap' {
+        BeforeAll {
+            InModuleScope PSDepend {
+                Mock Get-Command { $null } -ParameterFilter { $Name -eq 'Nuget' }
+                Mock BootStrap-Nuget { }
+                Mock Test-PlatformSupport { $true }
+            }
+        }
+
+        It 'Calls BootStrap-Nuget when nuget.exe is missing on a supported platform' {
+            $targetDir = (New-Item 'TestDrive:/psgnuget-bootstrap' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'PSDeploy' -DependencyType 'PSGalleryNuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName BootStrap-Nuget -ModuleName PSDepend -Times 1
+        }
+
+        It 'Does not invoke nuget install when nuget.exe is still missing after bootstrap' {
+            $targetDir = (New-Item 'TestDrive:/psgnuget-bootstrap-fail' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'PSDeploy' -DependencyType 'PSGalleryNuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName Invoke-ExternalCommand -ModuleName PSDepend -Times 0
+        }
+
+        It 'Does not call BootStrap-Nuget on an unsupported platform' {
+            InModuleScope PSDepend {
+                Mock Test-PlatformSupport { $false }
+            }
+            $targetDir = (New-Item 'TestDrive:/psgnuget-bootstrap-noplatform' -ItemType Directory -Force).FullName
+            $dep = New-PSDependFixture -DependencyName 'PSDeploy' -DependencyType 'PSGalleryNuget' -Target $targetDir
+            InModuleScope PSDepend -Parameters @{ Dep = $dep; ScriptPath = $script:ScriptPath } {
+                & $ScriptPath -Dependency $Dep -ErrorAction SilentlyContinue
+            }
+            Should -Invoke -CommandName BootStrap-Nuget -ModuleName PSDepend -Times 0
+        }
+    }
 }