fix: MockFileSystem.GetTempPath() returns real OS temp path by default

src/TestableIO.System.IO.Abstractions.TestingHelpers/MockFileSystem.cs

@@ -14,7 +14,6 @@ namespace System.IO.Abstractions.TestingHelpers;
 public class MockFileSystem : FileSystemBase, IMockFileDataAccessor
 {
     private const string DEFAULT_CURRENT_DIRECTORY = @"C:\";
-    private const string TEMP_DIRECTORY = @"C:\temp\";
 
     private readonly IDictionary<string, FileSystemEntry> files;
     private readonly IDictionary<string, MockDriveData> drives;
@@ -58,7 +57,9 @@ public MockFileSystem(IDictionary<string, MockFileData> files, MockFileSystemOpt
             throw new ArgumentException("Current directory needs to be rooted.", nameof(currentDirectory));
         }
 
-        var defaultTempDirectory = XFS.Path(TEMP_DIRECTORY);
+        var defaultTempDirectory = !string.IsNullOrEmpty(options.TemporaryDirectory)
+            ? options.TemporaryDirectory
+            : System.IO.Path.GetTempPath();
 
         StringOperations = new StringOperations(XFS.IsUnixPlatform());
         pathVerifier = new PathVerifier(this);

src/TestableIO.System.IO.Abstractions.TestingHelpers/MockFileSystemOptions.cs

@@ -14,4 +14,10 @@ public class MockFileSystemOptions
     /// Flag indicating, if a temporary directory should be created.
     /// </summary>
     public bool CreateDefaultTempDir { get; init; } = true;
+
+    /// <summary>
+    ///     The temporary directory used by the <see cref="MockFileSystem" />.
+    ///     Defaults to <see cref="System.IO.Path.GetTempPath()" /> when <see langword="null" /> or empty.
+    /// </summary>
+    public string? TemporaryDirectory { get; init; }
 }

tests/TestableIO.System.IO.Abstractions.TestingHelpers.Tests/MockPathTests.cs

@@ -412,6 +412,19 @@ public async Task GetTempPath_Called_ReturnsStringLengthGreaterThanZero(string t
         await That(result.Length > 0).IsTrue();
     }
 
+    [Test]
+    public async Task GetTempPath_Default_MatchesRealOsTempPath()
+    {
+        //Arrange
+        var mockPath = new MockFileSystem().Path;
+
+        //Act
+        var result = mockPath.GetTempPath();
+
+        //Assert
+        await That(result).IsEqualTo(System.IO.Path.GetTempPath());
+    }
+
     [Test]
     public async Task GetTempPath_Called_WithNonNullVirtualTempDirectory_ReturnsVirtualTempDirectory()
     {