feat: add tests

__std/misc/src/bin/cursor_test.rs

@@ -0,0 +1,17 @@
+use std::io::{BufRead, Cursor, Read};
+
+fn main() {
+    let mut cursor = Cursor::new(b"hello world\n001");
+    println!("{}", cursor.position());
+    let mut buff = [0_u8; 5];
+    cursor.read_exact(&mut buff).unwrap();
+    println!("{:x?}", buff);
+    println!("{}", cursor.position());
+    let mut s = String::new();
+    cursor.read_line(&mut s).unwrap();
+    println!("[{}]", s);
+    println!("{}", cursor.position());
+    let mut s2 = String::new();
+    cursor.read_to_string(&mut s2).unwrap();
+    println!("[{}]", s2);
+}