os: make behave more like Unix "mv" command (#6300)

vlib/os/os.v

@@ -58,10 +58,14 @@ pub fn file_size(path string) int {
 
 // mv moves files or folders from `src` to `dst`.
 pub fn mv(src, dst string) {
+	mut rdst := dst
+	if is_dir(rdst) {
+		rdst = join_path(rdst,file_name(src.trim_right(path_separator)))
+	}
 	$if windows {
-		C._wrename(src.to_wide(), dst.to_wide())
+		C._wrename(src.to_wide(), rdst.to_wide())
 	} $else {
-		C.rename(charptr(src.str), charptr(dst.str))
+		C.rename(charptr(src.str), charptr(rdst.str))
 	}
 }
 

vlib/os/os_test.v

@@ -156,6 +156,52 @@ fn test_cp() {
 	os.rm(new_file_name)
 }
 
+/*
+fn test_mv() {
+	work_dir := os.join_path(os.temp_dir(),'v','mv_test')
+	if os.exists(work_dir) {
+		os.rmdir_all(work_dir)
+	}
+	mkdir_all(work_dir)
+	// Setup test files
+	tfile1 := os.join_path(work_dir,'file')
+	tfile2 := os.join_path(work_dir,'file.test')
+	tfile3 := os.join_path(work_dir,'file.3')
+	tfile_content := 'temporary file'
+	os.write_file(tfile1, tfile_content)
+	os.write_file(tfile2, tfile_content)
+	// Setup test dirs
+	tdir1 := os.join_path(work_dir,'dir')
+	tdir2 := os.join_path(work_dir,'dir2')
+	tdir3 := os.join_path(work_dir,'dir3')
+	mkdir(tdir1)
+	mkdir(tdir2)
+	// Move file with no extension to dir
+	os.mv(tfile1,tdir1)
+	mut expected := os.join_path(tdir1,'file')
+	assert os.exists(expected) && !is_dir(expected) == true
+	// Move dir with contents to other dir
+	os.mv(tdir1,tdir2)
+	expected = os.join_path(tdir2,'dir')
+	assert os.exists(expected) && is_dir(expected) == true
+	expected = os.join_path(tdir2,'dir','file')
+	assert os.exists(expected) && !is_dir(expected) == true
+	// Move dir with contents to other dir (by renaming)
+	os.mv(os.join_path(tdir2,'dir'),tdir3)
+	expected = tdir3
+	assert os.exists(expected) && is_dir(expected) == true
+	assert os.is_dir_empty(tdir2) == true
+	// Move file with extension to dir
+	os.mv(tfile2,tdir2)
+	expected = os.join_path(tdir2,'file.test')
+	assert os.exists(expected) && !is_dir(expected) == true
+	// Move file to dir (by renaming)
+	os.mv(os.join_path(tdir2,'file.test'),tfile3)
+	expected = tfile3
+	assert os.exists(expected) && !is_dir(expected) == true
+}
+*/
+
 fn test_cp_r() {
 	// fileX -> dir/fileX
 	// NB: clean up of the files happens inside the cleanup_leftovers function