Add a test for core::str::from_cstr_len

Author: uasi

src/libcore/str.rs

@@ -1979,6 +1979,14 @@ mod tests {
         assert (c == "AAAAAAA");
     }
 
+    #[test]
+    fn test_from_cstr_len() unsafe {
+        let a = [65u8, 65u8, 65u8, 65u8, 65u8, 65u8, 65u8, 0u8];
+        let b = vec::to_ptr(a);
+        let c = from_cstr_len(b, 3u);
+        assert (c == "AAA");
+    }
+
     #[test]
     fn test_as_buf() unsafe {
         let a = "Abcdefg";