string: update split() method

vlib/builtin/string.v

@@ -310,8 +310,14 @@ fn (s string) add(a string) string {
 pub fn (s string) split(delim string) []string {
 	// println('string split delim="$delim" s="$s"')
 	mut res := []string
+	// if delim.len == 0 {
+	// 	res << s
+	// 	return res
+	// }
 	if delim.len == 0 {
-		res << s
+		for ch in s {
+			res << ch.str()
+		}
 		return res
 	}
 	if delim.len == 1 {

vlib/builtin/string_test.v

@@ -113,6 +113,17 @@ fn test_split() {
 	assert vals[0] == 'l'
 	assert vals[1] == 'l'
 	assert vals[2] == 'l'
+	// /////////
+	s = 'awesome'
+	a := s.split('')
+	assert a.len == 7
+	assert a[0] == 'a'
+	assert a[1] == 'w'
+	assert a[2] == 'e'
+	assert a[3] == 's'
+	assert a[4] == 'o'
+	assert a[5] == 'm'
+	assert a[6] == 'e'
 }
 
 fn test_trim_space() {