PathStrings: fix treatment of ""..." in the end of a path

Author: ForNeVeR

CHANGELOG.md

@@ -11,6 +11,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Incorrect path normalization: last ellipsis (`...`) in a path was treated as a `..` entry.
+
 ### Changed
 - [#18](https://github.com/ForNeVeR/TruePath/issues/18): update to behavior of `.Parent` on relative paths.
 

TruePath.Tests/AbsolutePathTests.cs

@@ -8,6 +8,14 @@ namespace TruePath.Tests;
 
 public class AbsolutePathTests
 {
+    [Fact]
+    public void ConstructionTest()
+    {
+        var root = new AbsolutePath(OperatingSystem.IsWindows() ? @"A:\" : "/");
+        var path = new AbsolutePath($"{root}/...");
+        Assert.Equal($"{root}...", path.Value);
+    }
+
     [Fact]
     public void ReadKind_NonExistent()
     {

TruePath.Tests/LocalPathTests.cs

@@ -20,6 +20,18 @@ public void AbsolutePathParent(string relativePath, string? expectedRelativePath
         Assert.Equal(expectedPath, parent.Parent);
     }
 
+    [Theory]
+    [InlineData(".", "")]
+    [InlineData("..", "..")]
+    [InlineData("../..", "../..")]
+    [InlineData(".../...", ".../...")]
+    [InlineData(".../..", "")]
+    public void ConstructionTest(string pathString, string expectedValue)
+    {
+        var path = new LocalPath(pathString);
+        Assert.Equal(expectedValue.Replace('/', Path.DirectorySeparatorChar), path.Value);
+    }
+
     [Theory]
     [InlineData(".", "..")]
     [InlineData("..", "../..")]

TruePath.Tests/PathStringsTests.cs

@@ -55,7 +55,11 @@ public void SeparatorsAreDeduplicated(string input, string expected)
     [InlineData("../../foo", "../../foo")]
     [InlineData("../../../foo", "../../../foo")]
     [InlineData("../foo/..", "..")]
-    public void DotFoldersAreTraversed(string input, string expected)
+    [InlineData("...", "...")]
+    [InlineData(".../..", "")]
+    [InlineData(".../...", ".../...")]
+    [InlineData(".../../...", "...")]
+    public void DotFoldersAreTraversedCorrectly(string input, string expected)
     {
         Assert.Equal(NormalizeSeparators(expected), PathStrings.Normalize(input));
     }

TruePath/PathStrings.cs

@@ -75,7 +75,12 @@ public static string Normalize(string path)
             else if (block.Length == 2 && block[0] == '.' && (block[1] == Path.DirectorySeparatorChar || block[1] == Path.AltDirectorySeparatorChar))
                 skip = true;
             // cut if '..' or '../'
-            else if (written != 0 && block.Length is 2 or 3 && block.StartsWith(".."))
+            else if (written != 0
+                && (
+                    block is ".."
+                    || block.SequenceEqual($"..{Path.DirectorySeparatorChar}")
+                    || block.SequenceEqual($"..{Path.AltDirectorySeparatorChar}")
+                ))
             {
                 var alreadyWrittenPart = normalized[..(written - 1)];
                 var jump = alreadyWrittenPart.LastIndexOf(Path.DirectorySeparatorChar);