Added Null and IsNull to eventually replace Empty

Author: dennisdoomen

Pathy.ApiVerificationTests/ApprovedApi/pathy.net47.verified.txt

@@ -11,13 +11,15 @@ namespace Pathy
         public bool FileExists { get; }
         public bool IsDirectory { get; }
         public bool IsFile { get; }
+        public bool IsNull { get; }
         public bool IsRooted { get; }
         public string Name { get; }
         public Pathy.ChainablePath Parent { get; }
         public Pathy.ChainablePath Root { get; }
         public static Pathy.ChainablePath Current { get; }
         public static Pathy.ChainablePath Empty { get; }
         public static Pathy.ChainablePath New { get; }
+        public static Pathy.ChainablePath Null { get; }
         public static Pathy.ChainablePath Temp { get; }
         public Pathy.ChainablePath FindParentWithFileMatching(params string[] wildcards) { }
         public bool HasExtension(string extension) { }

Pathy.ApiVerificationTests/ApprovedApi/pathy.net8.0.verified.txt

@@ -11,13 +11,15 @@ namespace Pathy
         public bool FileExists { get; }
         public bool IsDirectory { get; }
         public bool IsFile { get; }
+        public bool IsNull { get; }
         public bool IsRooted { get; }
         public string Name { get; }
         public Pathy.ChainablePath Parent { get; }
         public Pathy.ChainablePath Root { get; }
         public static Pathy.ChainablePath Current { get; }
         public static Pathy.ChainablePath Empty { get; }
         public static Pathy.ChainablePath New { get; }
+        public static Pathy.ChainablePath Null { get; }
         public static Pathy.ChainablePath Temp { get; }
         public Pathy.ChainablePath AsRelativeTo(Pathy.ChainablePath basePath) { }
         public Pathy.ChainablePath FindParentWithFileMatching(params string[] wildcards) { }

Pathy.ApiVerificationTests/ApprovedApi/pathy.netstandard2.0.verified.txt

@@ -11,13 +11,15 @@ namespace Pathy
         public bool FileExists { get; }
         public bool IsDirectory { get; }
         public bool IsFile { get; }
+        public bool IsNull { get; }
         public bool IsRooted { get; }
         public string Name { get; }
         public Pathy.ChainablePath Parent { get; }
         public Pathy.ChainablePath Root { get; }
         public static Pathy.ChainablePath Current { get; }
         public static Pathy.ChainablePath Empty { get; }
         public static Pathy.ChainablePath New { get; }
+        public static Pathy.ChainablePath Null { get; }
         public static Pathy.ChainablePath Temp { get; }
         public Pathy.ChainablePath FindParentWithFileMatching(params string[] wildcards) { }
         public bool HasExtension(string extension) { }

Pathy.ApiVerificationTests/ApprovedApi/pathy.netstandard2.1.verified.txt

@@ -11,13 +11,15 @@ namespace Pathy
         public bool FileExists { get; }
         public bool IsDirectory { get; }
         public bool IsFile { get; }
+        public bool IsNull { get; }
         public bool IsRooted { get; }
         public string Name { get; }
         public Pathy.ChainablePath Parent { get; }
         public Pathy.ChainablePath Root { get; }
         public static Pathy.ChainablePath Current { get; }
         public static Pathy.ChainablePath Empty { get; }
         public static Pathy.ChainablePath New { get; }
+        public static Pathy.ChainablePath Null { get; }
         public static Pathy.ChainablePath Temp { get; }
         public Pathy.ChainablePath AsRelativeTo(Pathy.ChainablePath basePath) { }
         public Pathy.ChainablePath FindParentWithFileMatching(params string[] wildcards) { }

Pathy.Specs/ChainablePathSpecs.cs

@@ -568,7 +568,7 @@ public void Empty_path_returned_when_no_match_found()
         var result = childDir.FindParentWithFileMatching("*.sln");
 
         // Assert
-        result.Should().Be(ChainablePath.Empty);
+        result.Should().Be(ChainablePath.Null);
     }
 
     [Fact]
@@ -765,7 +765,7 @@ public void Returns_empty_for_non_existing_string_paths()
         var result = ChainablePath.FindFirst(nonExistingFile1.ToString(), nonExistingFile2.ToString());
 
         // Assert
-        result.Should().Be(ChainablePath.Empty);
+        result.IsNull.Should().BeTrue();
     }
 
     [Fact]

Pathy/ChainablePath.cs

@@ -32,6 +32,14 @@ private ChainablePath(string path)
     /// </summary>
     public static ChainablePath Empty { get; } = new(string.Empty);
 
+    /// <summary>
+    /// Represents a <see cref="ChainablePath"/> not pointing to any file or directory.
+    /// </summary>
+    /// <remarks>
+    /// Implements the Null Pattern and should be used as a replacement of <see cref="Empty"/>
+    /// </remarks>
+    public static ChainablePath Null { get; } = new(string.Empty);
+
     /// <summary>
     /// Gets a default, empty <see cref="ChainablePath"/> instance.
     /// </summary>
@@ -221,6 +229,11 @@ private static string NormalizeSlashes(string path)
         return From(leftPath.ToString() + additionalPath);
     }
 
+    /// <summary>
+    /// Gets a value indicating whether the current <see cref="ChainablePath"/> instance is equal to <see cref="ChainablePath.Null"/>.
+    /// </summary>
+    public bool IsNull => Equals(Null);
+
     /// <summary>
     /// Gets the name of the file or directory represented by the current path, without the parent directory.
     /// </summary>