Return correct casing of filesystem path during normalization

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

@@ -98,7 +98,75 @@ public FileSystemProvider()
         /// </returns>
         private static string NormalizePath(string path)
         {
-            return path.Replace(StringLiterals.AlternatePathSeparator, StringLiterals.DefaultPathSeparator);
+            return GetCorrectCasedPath(path.Replace(StringLiterals.AlternatePathSeparator, StringLiterals.DefaultPathSeparator));
+        }
+
+        /// <summary>
+        /// Get the correct casing for a path.  This method assumes it's being called by NormalizePath()
+        /// so that the path is already normalized.
+        /// </summary>
+        /// <param name="path">
+        /// The path to retrieve.
+        /// </param>
+        /// <returns>
+        /// The path with accurate casing if item exists, otherwise it returns path that was passed in.
+        /// </returns>
+        private static string GetCorrectCasedPath(string path)
+        {
+            // Only apply to directories where there are issues with some tools if the casing
+            // doesn't match the source like git
+            if (Directory.Exists(path))
+            {
+                string exactPath = string.Empty;
+                int itemsToSkip = 0;
+                if (Utils.PathIsUnc(path))
+                {
+                    // With the Split method, a UNC path like \\server\share, we need to skip
+                    // trying to enumerate the server and share, so skip the first two empty
+                    // strings, then server, and finally share name.
+                    itemsToSkip = 4;
+                }
+
+                foreach (string item in path.Split(StringLiterals.DefaultPathSeparator))
+                {
+                    if (itemsToSkip-- > 0)
+                    {
+                        // This handles the UNC server and share and 8.3 short path syntax
+                        exactPath += item + StringLiterals.DefaultPathSeparator;
+                        continue;
+                    }
+                    else if (string.IsNullOrEmpty(exactPath))
+                    {
+                        // This handles the drive letter or / root path start
+                        exactPath = item + StringLiterals.DefaultPathSeparator;
+                    }
+                    else if (string.IsNullOrEmpty(item))
+                    {
+                        // This handles the trailing slash case
+                        continue;
+                    }
+                    else if (item.Contains('~'))
+                    {
+                        // This handles short path names
+                        exactPath += StringLiterals.DefaultPathSeparator + item;
+                    }
+                    else
+                    {
+                        exactPath = Directory.GetFileSystemEntries(exactPath, item).First();
+                    }
+                }
+
+                if (path.EndsWith(StringLiterals.DefaultPathSeparator))
+                {
+                    return exactPath + StringLiterals.DefaultPathSeparator;
+                }
+
+                return exactPath;
+            }
+            else
+            {
+                return path;
+            }
         }
 
         /// <summary>

test/powershell/Modules/Microsoft.PowerShell.Management/Set-Location.Tests.ps1

@@ -70,6 +70,24 @@ Describe "Set-Location" -Tags "CI" {
             Should -Throw -ErrorId "PathNotFound,Microsoft.PowerShell.Commands.SetLocationCommand"
     }
 
+    It "Should use actual casing of folder on case-insensitive filesystem" -Skip:($IsLinux) {
+        $testPath = New-Item -ItemType Directory -Path testdrive:/teST
+        Set-Location $testPath.FullName.ToUpper()
+        $(Get-Location).Path | Should -BeExactly $testPath.FullName
+    }
+
+    It "Should use actual casing of folder on case-sensitive filesystem: <dir>" -Skip:(!$IsLinux)
+    {
+        $dir = "teST"
+        $testPathLower = New-Item -ItemType Directory -Path (Join-Path $TestDrive $dir.ToLower())
+        $testPathUpper = New-Item -ItemType Directory -Path (Join-Path $TestDrive $dir.ToUpper())
+        Set-Location $testPathLower.FullName
+        $(Get-Location).Path | Should -BeExactly $testPathLower.FullName
+        Set-Location $testPathUpper.FullName
+        $(Get-Location).Path | Should -BeExactly $testPathUpper.FullName
+        { Set-Locaiton (Join-Path $TestDrive $dir) } | Should -Throw -ErrorId "PathNotFound,Microsoft.PowerShell.Commands.SetLocationCommand"
+    }
+
     Context 'Set-Location with no arguments' {
 
         It 'Should go to $env:HOME when Set-Location run with no arguments from FileSystem provider' {