Fix MockFileInfo.FullName - normalize paths (#482)

Fixes #425

Author: 304NotModified

System.IO.Abstractions.TestingHelpers.Tests/MockFileInfoTests.cs

@@ -536,6 +536,35 @@ public void MockFileInfo_ToString_ShouldReturnOriginalFilePath(string path)
             Assert.AreEqual(filePath, mockFileInfo.ToString());
         }
 
+
+        /// <summary>
+        /// Normalize, tested with Path.GetFullPath and new FileInfo().FullName;
+        /// </summary>
+        [TestCaseSource(nameof(FromFileName_Paths_NormalizePaths_Cases))]
+        public void FromFileName_Paths_NormalizePaths(string input, string expected)
+        {
+            // Arrange
+            var mockFs = new MockFileSystem();
+
+            // Act
+            var mockFileInfo = mockFs.FileInfo.FromFileName(input);
+            var result = mockFileInfo.FullName;
+
+            // Assert
+            Assert.AreEqual(expected, result);
+        }
+
+        public static IEnumerable<string[]> FromFileName_Paths_NormalizePaths_Cases
+        {
+            get
+            {
+                yield return new[] { XFS.Path(@"c:\top\..\most\file"), XFS.Path(@"c:\most\file") };
+                yield return new[] { XFS.Path(@"c:\top\..\most\..\dir\file"), XFS.Path(@"c:\dir\file") };
+                yield return new[] { XFS.Path(@"\file"), XFS.Path(@"C:\file") };
+                yield return new[] { XFS.Path(@"c:\top\../..\most\file"), XFS.Path(@"c:\most\file") };
+            }
+        }
+
 #if NET40
         [Test]
         public void MockFileInfo_Replace_ShouldReplaceFileContents()

System.IO.Abstractions.TestingHelpers/MockFileInfo.cs

@@ -7,11 +7,14 @@ public class MockFileInfo : FileInfoBase
     {
         private readonly IMockFileDataAccessor mockFileSystem;
         private string path;
+        private string originalPath;
 
         public MockFileInfo(IMockFileDataAccessor mockFileSystem, string path) : base(mockFileSystem?.FileSystem)
         {
             this.mockFileSystem = mockFileSystem ?? throw new ArgumentNullException(nameof(mockFileSystem));
-            this.path = path ?? throw new ArgumentNullException(nameof(path));
+            this.originalPath = path ?? throw new ArgumentNullException(nameof(path));
+            this.path = mockFileSystem.Path.GetFullPath(path);
+
         }
 
         MockFileData MockFileData
@@ -314,7 +317,7 @@ public override long Length
 
         public override string ToString()
         {
-            return path;
+            return originalPath;
         }
     }
 }