Check if destination exists in Directory.Move (#17913)

* Check if destination exists in Directory.Move

Fixes #12396

* Fix tests

* Update DirectoryInfo.MoveTo as well

3 files changed, 30 insertions, 26 deletions

diff --git a/src/System.IO.FileSystem/src/System/IO/Directory.cs b/src/System.IO.FileSystem/src/System/IO/Directory.cs
index 3187d75e36..44271c579b 100644
--- a/src/System.IO.FileSystem/src/System/IO/Directory.cs
+++ b/src/System.IO.FileSystem/src/System/IO/Directory.cs
@@ -563,6 +563,12 @@ namespace System.IO
             String destinationRoot = Path.GetPathRoot(destPath);
             if (!String.Equals(sourceRoot, destinationRoot, pathComparison))
                 throw new IOException(SR.IO_SourceDestMustHaveSameRoot);
+            
+            if (!FileSystem.Current.DirectoryExists(fullsourceDirName))
+                throw new DirectoryNotFoundException(SR.Format(SR.IO_PathNotFound_Path, fullsourceDirName));
+            
+            if (FileSystem.Current.DirectoryExists(fulldestDirName))
+                throw new IOException(SR.Format(SR.IO_AlreadyExists_Name, fulldestDirName));
 
             FileSystem.Current.MoveDirectory(fullsourceDirName, fulldestDirName);
         }
diff --git a/src/System.IO.FileSystem/src/System/IO/DirectoryInfo.cs b/src/System.IO.FileSystem/src/System/IO/DirectoryInfo.cs
index 95b448412c..177177d9c4 100644
--- a/src/System.IO.FileSystem/src/System/IO/DirectoryInfo.cs
+++ b/src/System.IO.FileSystem/src/System/IO/DirectoryInfo.cs
@@ -413,6 +413,12 @@ namespace System.IO
             if (!String.Equals(sourceRoot, destinationRoot, pathComparison))
                 throw new IOException(SR.IO_SourceDestMustHaveSameRoot);
 
+            if (!Exists)
+                throw new DirectoryNotFoundException(SR.Format(SR.IO_PathNotFound_Path, FullPath));
+
+            if (FileSystem.Current.DirectoryExists(fullDestDirName))
+                throw new IOException(SR.Format(SR.IO_AlreadyExists_Name, fullDestDirName));
+
             FileSystem.Current.MoveDirectory(FullPath, fullDestDirName);
 
             FullPath = fullDestDirName;
diff --git a/src/System.IO.FileSystem/tests/Directory/Move.cs b/src/System.IO.FileSystem/tests/Directory/Move.cs
index 63588f5cce..586e1e4db0 100644
--- a/src/System.IO.FileSystem/tests/Directory/Move.cs
+++ b/src/System.IO.FileSystem/tests/Directory/Move.cs
@@ -42,13 +42,30 @@ namespace System.IO.Tests
         }
 
         [Fact]
-        public void MoveOntoExistingDirectory()
+        public void MoveOntoSameDirectory()
         {
             DirectoryInfo testDir = Directory.CreateDirectory(GetTestFilePath());
             Assert.Throws<IOException>(() => Move(testDir.FullName, testDir.FullName));
         }
 
         [Fact]
+        public void MoveOntoExistingDirectory()
+        {
+            DirectoryInfo testDir = Directory.CreateDirectory(GetTestFilePath());
+            DirectoryInfo secondDir = Directory.CreateDirectory(GetTestFilePath());
+            Assert.Throws<IOException>(() => Move(testDir.FullName, secondDir.FullName));
+        }
+
+        [Fact]
+        public void MoveOntoFile()
+        {
+            DirectoryInfo testDir = Directory.CreateDirectory(GetTestFilePath());
+            string testFile = GetTestFilePath();
+            File.WriteAllText(testFile, "");
+            Assert.Throws<IOException>(() => Move(testDir.FullName, testFile));
+        }
+
+        [Fact]
         public void MoveIntoCurrentDirectory()
         {
             DirectoryInfo testDir = Directory.CreateDirectory(GetTestFilePath());
@@ -261,31 +278,6 @@ namespace System.IO.Tests
                 Assert.Throws<IOException>(() => Move(path, "D:\\DoesntExist"));
         }
 
-        [ConditionalFact(nameof(PlatformDetection) + "." + nameof(PlatformDetection.IsNotWindowsSubsystemForLinux))] // https://github.com/Microsoft/BashOnWindows/issues/1008
-        [PlatformSpecific(TestPlatforms.AnyUnix)]  // Moving to existing directory allowed for empty directory, but causes IOException for non-empty directory
-        public void UnixExistingDirectory()
-        {
-            // Moving to an-empty directory is supported on Unix, but moving to a non-empty directory is not
-            string testDirSource = GetTestFilePath();
-            string testDirDestEmpty = GetTestFilePath();
-            string testDirDestNonEmpty = GetTestFilePath();
-
-            Directory.CreateDirectory(testDirSource);
-            Directory.CreateDirectory(testDirDestEmpty);
-            Directory.CreateDirectory(testDirDestNonEmpty);
-
-            using (File.Create(Path.Combine(testDirDestNonEmpty, GetTestFileName())))
-            {
-                Assert.Throws<IOException>(() => Move(testDirSource, testDirDestNonEmpty));
-                Assert.True(Directory.Exists(testDirDestNonEmpty));
-                Assert.True(Directory.Exists(testDirSource));
-            }
-
-            Move(testDirSource, testDirDestEmpty);
-            Assert.True(Directory.Exists(testDirDestEmpty));
-            Assert.False(Directory.Exists(testDirSource));
-        }
-
         #endregion
     }
 }