Simplify parent lookup with Directory.GetParent (#1455)

* Simplify parent lookup with Directory.GetParent

* Address comments

API.Tests/Services/DirectoryServiceTests.cs

@@ -963,5 +963,36 @@ namespace API.Tests.Services
     }
 
     #endregion
+
+        #region GetParentDirectory
+
+        [Theory]
+        [InlineData(@"C:/file.txt", "C:/")]
+        [InlineData(@"C:/folder/file.txt", "C:/folder")]
+        [InlineData(@"C:/folder/subfolder/file.txt", "C:/folder/subfolder")]
+        public void GetParentDirectoryName_ShouldFindParentOfFiles(string path, string expected)
+        {
+            var fileSystem = new MockFileSystem(new Dictionary<string, MockFileData>
+            {
+                { path, new MockFileData(string.Empty)}
+            });
+
+            var ds = new DirectoryService(Substitute.For<ILogger<DirectoryService>>(), fileSystem);
+            Assert.Equal(expected, ds.GetParentDirectoryName(path));
+        }
+        [Theory]
+        [InlineData(@"C:/folder", "C:/")]
+        [InlineData(@"C:/folder/subfolder", "C:/folder")]
+        [InlineData(@"C:/folder/subfolder/another", "C:/folder/subfolder")]
+        public void GetParentDirectoryName_ShouldFindParentOfDirectories(string path, string expected)
+        {
+            var fileSystem = new MockFileSystem();
+            fileSystem.AddDirectory(path);
+
+            var ds = new DirectoryService(Substitute.For<ILogger<DirectoryService>>(), fileSystem);
+            Assert.Equal(expected, ds.GetParentDirectoryName(path));
+        }
+
+        #endregion
     }
 }

API/Services/DirectoryService.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.IO;
@@ -554,31 +554,18 @@ namespace API.Services
        /// <summary>
        /// Returns the parent directories name for a file or folder. Empty string is path is not valid.
        /// </summary>
-       /// <remarks>This does touch I/O with an Attribute lookup</remarks>
        /// <param name="fileOrFolder"></param>
        /// <returns></returns>
        public string GetParentDirectoryName(string fileOrFolder)
        {
-           // TODO: Write Unit tests
+            try
-           try
+            {
-           {
+                return Parser.Parser.NormalizePath(Directory.GetParent(fileOrFolder).FullName);
-               var attr = File.GetAttributes(fileOrFolder);
+            }
-               var isDirectory = attr.HasFlag(FileAttributes.Directory);
+            catch (Exception)
-               if (isDirectory)
+            {
-               {
+                return string.Empty;
-                   return Parser.Parser.NormalizePath(FileSystem.DirectoryInfo
+            }
-                       .FromDirectoryName(fileOrFolder).Parent
-                       .FullName);
-               }
-
-               return Parser.Parser.NormalizePath(FileSystem.FileInfo
-                   .FromFileName(fileOrFolder).Directory.Parent
-                   .FullName);
-           }
-           catch (Exception)
-           {
-               return string.Empty;
-           }
        }
 
        /// <summary>