Add ItemSeparator and AltItemSeparator properties in ProviderInfo (#8587)

Add two properties in `ProviderInfo` class: `ItemSeparator` and `AltItemSeparator`.
On windows, the default values for those two properties are `ItemSeparator = '\'` and `AltItemSeparator = '/'`.
On unix, the default values for those two properties are `ItemSeparator = '/'` and `AltItemSeparator = '\'`.

Registry provider is the only exception, both properties for it have the value `\`.

src/Microsoft.PowerShell.Security/security/CertificateProvider.cs

@@ -942,6 +942,7 @@ namespace Microsoft.PowerShell.Commands
                                  StoreLocation.LocalMachine);
             WriteItemObject(outStore, path, true);
         }
+
         #region DriveCmdletProvider overrides
 
         /// <summary>

src/System.Management.Automation/engine/DataStoreAdapterProvider.cs

@@ -259,6 +259,16 @@ namespace System.Management.Automation
         /// </summary>
         public bool VolumeSeparatedByColon { get; internal set; } = true;
 
+        /// <summary>
+        /// Gets the default item separator character for this provider.
+        /// </summary>
+        public char ItemSeparator { get; private set; }
+
+        /// <summary>
+        /// Gets the alternate item separator character for this provider.
+        /// </summary>
+        public char AltItemSeparator { get; private set; }
+
         /// <summary>
         /// Constructs an instance of the class using an existing reference
         /// as a template.
@@ -292,6 +302,8 @@ namespace System.Management.Automation
             PSSnapIn = providerInfo.PSSnapIn;
             _sessionState = providerInfo._sessionState;
             VolumeSeparatedByColon = providerInfo.VolumeSeparatedByColon;
+            ItemSeparator = providerInfo.ItemSeparator;
+            AltItemSeparator = providerInfo.AltItemSeparator;
         }
 
         /// <summary>
@@ -606,6 +618,8 @@ namespace System.Management.Automation
             }
 
             Provider.CmdletProvider result = providerInstance as Provider.CmdletProvider;
+            ItemSeparator = result.ItemSeparator;
+            AltItemSeparator = result.AltItemSeparator;
 
             Dbg.Diagnostics.Assert(
                 result != null,

src/System.Management.Automation/namespaces/AliasProvider.cs

@@ -316,6 +316,7 @@ namespace Microsoft.PowerShell.Commands
 
             return result;
         }
+
         #endregion protected members
 
     }

src/System.Management.Automation/namespaces/FileSystemProvider.cs

@@ -340,8 +340,9 @@ namespace Microsoft.PowerShell.Commands
         #endregion
 
         #region CmdletProvider members
+
         /// <summary>
-        /// Starts the File System provider.  This method sets the Home for the
+        /// Starts the File System provider. This method sets the Home for the
         /// provider to providerInfo.Home if specified, and %USERPROFILE%
         /// otherwise.
         /// </summary>
@@ -354,7 +355,7 @@ namespace Microsoft.PowerShell.Commands
         protected override ProviderInfo Start(ProviderInfo providerInfo)
         {
             // Set the home folder for the user
-            if (providerInfo != null && string.IsNullOrEmpty(providerInfo.Home))
+            if (providerInfo != null && string.IsNullOrEmpty(providerInfo.Home)) 
             {
                 // %USERPROFILE% - indicate where a user's home directory is located in the file system.
                 string homeDirectory = Environment.GetEnvironmentVariable(Platform.CommonEnvVariableNames.Home);

src/System.Management.Automation/namespaces/ProviderBase.cs

@@ -5,6 +5,7 @@
 #pragma warning disable 56506
 
 using System.Collections.ObjectModel;
+using System.IO;
 using System.Management.Automation.Runspaces;
 using System.Management.Automation.Internal;
 using System.Management.Automation.Host;
@@ -1384,6 +1385,21 @@ namespace System.Management.Automation.Provider
             }
         }
 
+        /// <summary>
+        /// Gets the default item separator character for this provider.
+        /// </summary>
+        public virtual char ItemSeparator => Path.DirectorySeparatorChar;
+
+        /// <summary>
+        /// Gets the alternate item separator character for this provider.
+        /// </summary>
+        public virtual char AltItemSeparator =>
+#if UNIX
+            Utils.Separators.Backslash[0];
+#else
+            Path.AltDirectorySeparatorChar;
+#endif
+
         #region IResourceSupplier
         /// <summary>
         /// Gets the resource string corresponding to baseName and

src/System.Management.Automation/namespaces/RegistryProvider.cs

@@ -86,6 +86,15 @@ namespace Microsoft.PowerShell.Commands
         /// </summary>
         public const string ProviderName = "Registry";
 
+        #region CmdletProvider overrides
+
+        /// <summary>
+        /// Gets the alternate item separator character for this provider.
+        /// </summary>
+        public override char AltItemSeparator => ItemSeparator;
+
+        #endregion
+
         #region DriveCmdletProvider overrides
 
         /// <summary>

test/powershell/Modules/Microsoft.PowerShell.Management/Get-PSProvider.Tests.ps1

@@ -24,4 +24,43 @@ Describe "Get-PSProvider" -Tags "CI" {
 
 	{ $actual | Format-List } | Should -Not -Throw
     }
+
+    Context 'ItemSeparator properties' {
+        BeforeAll {
+            $testCases = if ($IsWindows) {
+                            @(
+                                @{Provider = 'FileSystem'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Variable'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Function'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Alias'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Environment'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Certificate'; ItemSeparator = '\'; AltItemSeparator = '/'}
+                                @{Provider = 'Registry'; ItemSeparator = '\'; AltItemSeparator = '\'}
+                            )
+                        }
+                        else {
+                            @(
+                                @{Provider = 'FileSystem'; ItemSeparator = '/'; AltItemSeparator = '\'}
+                                @{Provider = 'Variable'; ItemSeparator = '/'; AltItemSeparator = '\'}
+                                @{Provider = 'Function'; ItemSeparator = '/'; AltItemSeparator = '\'}
+                                @{Provider = 'Alias'; ItemSeparator = '/'; AltItemSeparator = '\'}
+                                @{Provider = 'Environment'; ItemSeparator = '/'; AltItemSeparator = '\'}
+                            )
+                        }
+        }
+
+        It '<Provider> provider has ItemSeparator properties' -TestCases $testCases {
+            param ($Provider, $ItemSeparator, $AltItemSeparator)
+
+            (Get-PSProvider $Provider).ItemSeparator | Should -Be $ItemSeparator
+            (Get-PSProvider $Provider).AltItemSeparator | Should -Be $AltItemSeparator
+        }
+
+        It 'ItemSeparator properties is read-only in <Provider> provider' -TestCases $testCases {
+            param ($Provider, $ItemSeparator, $AltItemSeparator)
+
+            { (Get-PSProvider $Provider).ItemSeparator = $null } | Should -Throw
+            { (Get-PSProvider $Provider).AltItemSeparator = $null } | Should -Throw
+        }
+    }
 }

test/powershell/Modules/Microsoft.WSMan.Management/ConfigProvider.Tests.ps1

@@ -439,4 +439,17 @@ Describe "WSMan Config Provider" -Tag Feature,RequireAdminOnWindows {
             }
         }
     }
+
+    Context 'ItemSeparator properties' {
+        It 'WSMan provider has ItemSeparator properties' {
+
+            (Get-PSProvider WSMan).ItemSeparator | Should -Be '\'
+            (Get-PSProvider WSMan).AltItemSeparator | Should -Be '/'
+        }
+
+        It 'ItemSeparator properties is read-only in WSMan provider' {
+            { (Get-PSProvider WSMan).ItemSeparator = $null } | Should -Throw
+            { (Get-PSProvider WSMan).AltItemSeparator = $null } | Should -Throw
+        }
+    }
 }