[bugfix] Fix IndexError crash of osext.copytree() when the source directory does not exist

reframe/utility/osext.py

@@ -156,7 +156,20 @@ def copytree(src, dst, symlinks=False, ignore=None, copy_function=shutil.copy2,
         return shutil.copytree(src, dst, symlinks, ignore, copy_function,
                                ignore_dangling_symlinks)
 
-    # dst exists; manually descend into the subdirectories
+    # dst exists; manually descend into the subdirectories, but do some sanity
+    # checking first
+
+    # We raise the following errors to comply with the copytree()'s behaviour
+
+    if not os.path.isdir(dst):
+        raise FileExistsError(errno.EEXIST, 'File exists', dst)
+
+    if not os.path.exists(src):
+        raise FileNotFoundError(errno.ENOENT, 'No such file or directory', src)
+
+    if not os.path.isdir(src):
+        raise NotADirectoryError(errno.ENOTDIR, 'Not a directory', src)
+
     _, subdirs, files = list(os.walk(src))[0]
     ignore_paths = ignore(src, os.listdir(src)) if ignore else {}
     for f in files:

unittests/test_utility.py

@@ -80,6 +80,37 @@ def test_copytree_src_parent_of_dst(tmp_path):
         osext.copytree(str(src_path), str(dst_path))
 
 
+@pytest.fixture(params=['dirs_exist_ok=True', 'dirs_exist_ok=False'])
+def dirs_exist_ok(request):
+    return 'True' in request.param
+
+
+def test_copytree_dst_notdir(tmp_path, dirs_exist_ok):
+    dir_src = tmp_path / 'src'
+    dir_src.mkdir()
+    dst = tmp_path / 'dst'
+    dst.touch()
+    with pytest.raises(FileExistsError, match=fr'{dst}'):
+        osext.copytree(str(dir_src), str(dst), dirs_exist_ok=dirs_exist_ok)
+
+
+def test_copytree_src_notdir(tmp_path, dirs_exist_ok):
+    src = tmp_path / 'src'
+    src.touch()
+    dst = tmp_path / 'dst'
+    dst.mkdir()
+    with pytest.raises(NotADirectoryError, match=fr'{src}'):
+        osext.copytree(str(src), str(dst), dirs_exist_ok=dirs_exist_ok)
+
+
+def test_copytree_src_does_not_exist(tmp_path, dirs_exist_ok):
+    src = tmp_path / 'src'
+    dst = tmp_path / 'dst'
+    dst.mkdir()
+    with pytest.raises(FileNotFoundError, match=fr'{src}'):
+        osext.copytree(str(src), str(dst), dirs_exist_ok=dirs_exist_ok)
+
+
 @pytest.fixture
 def rmtree(tmp_path):
     testdir = tmp_path / 'test'