Add a public API for getting locations of PSModulePath elements (#19422)

src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs

@@ -1172,6 +1172,42 @@ namespace System.Management.Automation
             return result.ToString();
         }
 
+        /// <summary>
+        /// The available module path scopes.
+        /// </summary>
+        public enum PSModulePathScope
+        {
+            /// <summary>The users module path.</summary>
+            User,
+
+            /// <summary>The Builtin module path. This is where PowerShell is installed (PSHOME).</summary>
+            Builtin,
+
+            /// <summary>The machine module path. This is the shared location for all users of the system.</summary>
+            Machine
+        }
+
+        /// <summary>
+        /// Retrieve the current PSModulePath for the specified scope.
+        /// </summary>
+        /// <param name="scope">The scope of module path to retrieve. This can be User, Builtin, or Machine.</param>
+        /// <returns>The string representing the requested module path type.</returns>
+        public static string GetPSModulePath(PSModulePathScope scope)
+        {
+            if (scope == PSModulePathScope.User)
+            {
+                return GetPersonalModulePath();
+            }
+            else if (scope == PSModulePathScope.Builtin)
+            {
+                return GetPSHomeModulePath();
+            }
+            else
+            {
+                return GetSharedModulePath();
+            }
+        }
+
         /// <summary>
         /// Checks the various PSModulePath environment string and returns PSModulePath string as appropriate.
         /// </summary>

test/powershell/engine/Module/ModulePath.Tests.ps1

@@ -202,3 +202,48 @@ Describe "SxS Module Path Basic Tests" -tags "CI" {
         $out.Split([System.IO.Path]::PathSeparator, [System.StringSplitOptions]::RemoveEmptyEntries) | Should -Not -BeLike $validation
     }
 }
+
+Describe "ModuleIntrinsics.GetPSModulePath API tests" -tag @('CI', 'RequireAdminOnWindows', 'RequireSudoOnUnix') {
+    BeforeAll {
+        # create a local repostory and install a module
+        $localSourceName = [Guid]::NewGuid().ToString("n")
+        $localSourceLocation = Join-Path $PSScriptRoot assets
+        Register-PSRepository -Name $localSourceName -SourceLocation $localSourceLocation -InstallationPolicy Trusted -ErrorAction SilentlyContinue
+        Install-Module -Force -Scope AllUsers -Name PowerShell.TestPackage -Repository $localSourceName -ErrorAction SilentlyContinue
+        Install-Module -Force -Scope CurrentUser -Name PowerShell.TestPackage -Repository $localSourceName -ErrorAction SilentlyContinue
+
+        $testCases = @(
+            @{ Name = "User"   ; Expected = $IsWindows ?
+                (Resolve-Path ([Environment]::GetFolderPath("Personal") + "\PowerShell\Modules")).Path :
+                (Resolve-Path ([System.Management.Automation.Platform]::SelectProductNameForDirectory("USER_MODULES"))).Path
+                }
+            @{ Name = "Machine" ; Expected = $IsWindows ?
+                [Environment]::GetFolderPath("ProgramFiles") + "\PowerShell\Modules" :
+                (Resolve-Path ([System.Management.Automation.Platform]::SelectProductNameForDirectory("SHARED_MODULES"))).Path
+            }
+            @{ Name = "Builtin" ; Expected = (Resolve-Path (Join-Path $PSHOME Modules)).Path }
+        )
+        # resolve the paths to ensure they are in the correct format
+        $currentModulePathElements = $env:PSModulePath -split [System.IO.Path]::PathSeparator | Foreach-Object { (Resolve-Path $_).Path }
+    }
+
+    AfterAll {
+        Unregister-PSRepository -Name $localSourceName -ErrorAction SilentlyContinue
+    }
+
+    It "The value '<Name>' should return the proper value" -testcase $testCases {
+        param ( $Name, $Expected )
+        $result = [System.Management.Automation.ModuleIntrinsics]::GetPSModulePath($name)
+        $result | Should -not -BeNullOrEmpty
+        # spot check pshome, the user and shared paths may not be present
+        if ( $name -eq "PSHOME") {
+            $result | Should -Be $Expected
+        }
+    }
+
+    It "The current module path should contain the expected paths for '<Name>'" -testcase $testCases {
+        param ( $Name, $Expected )
+        $mPath = (Resolve-Path ([System.Management.Automation.ModuleIntrinsics]::GetPSModulePath($name))).Path
+        $currentModulePathElements | Should -Contain $mPath
+    }
+}