Make sure the thrown exception for mkdir is "ALREADY_EXISTS" (#91)

Author: floitsch

src/directory.toit

@@ -13,7 +13,12 @@ The default directory separator for the underlying operating system.
 */
 SEPARATOR/string ::= (system.platform == system.PLATFORM-WINDOWS) ? "\\" : "/"
 
-/** Removes an empty directory. */
+/**
+Removes an empty directory.
+
+Throws a "FILE_NOT_FOUND" exception if the path does not exist or
+  is not a directory.
+*/
 rmdir path/string -> none:
   #primitive.file.rmdir
 
@@ -24,14 +29,17 @@ Does not follow symlinks, but removes the symlink itself.
 
 If $force is true, also deletes files in read-only directories. This only
   has an effect when $recursive is set.
+
+Throws a "FILE_NOT_FOUND" exception if the path does not exist or
+  is not a directory.
 */
 rmdir path/string --recursive/bool --force/bool=false -> none:
   if not recursive:
     rmdir path
     return
   dir-stat := file.stat --no-follow-links path
-  if dir-stat[file.ST-TYPE] != file.DIRECTORY:
-    throw "NOT_A_DIRECTORY"
+  if not dir-stat or dir-stat[file.ST-TYPE] != file.DIRECTORY:
+    throw "FILE_NOT_FOUND"
 
   // A queue of directories to delete. Each entry is a pair of a path and a
   // boolean indicating whether the directory is known to be empty.

tests/mkdir_rmdir_fail_test.toit

@@ -0,0 +1,30 @@
+// Copyright (C) 2025 Toit contributors.
+// Use of this source code is governed by a Zero-Clause BSD license that can
+// be found in the tests/TESTS_LICENSE file.
+
+import expect show *
+import system
+
+import host.file
+import host.directory show *
+
+with-tmp-dir [block]:
+  tmp-dir := mkdtemp "/tmp/mkdir-rmdir-test-"
+  try:
+    block.call tmp-dir
+  finally:
+    rmdir --recursive --force tmp-dir
+
+main:
+  with-tmp-dir: | tmp-dir |
+    mkdir "$tmp-dir/foo"
+    expect-throw "ALREADY_EXISTS": mkdir "$tmp-dir/foo"
+
+    not-found-path := "$tmp-dir-/bar"
+    expect-throw "FILE_NOT_FOUND": rmdir not-found-path
+    expect-throw "FILE_NOT_FOUND": rmdir --recursive not-found-path
+
+    not-dir-path := "$tmp-dir/file.txt"
+    file.write-contents "not a directory" --path=not-dir-path
+    expect-throw "FILE_NOT_FOUND": rmdir not-dir-path
+    expect-throw "FILE_NOT_FOUND": rmdir --recursive not-dir-path