| 248 | |
| 249 | #[test] |
| 250 | fn stack_ops() { |
| 251 | let mut stack = Stack::new(); |
| 252 | |
| 253 | // [] |
| 254 | assert!(stack.is_empty()); |
| 255 | assert_eq!(stack.peek(), None); |
| 256 | assert_eq!(stack.pop(), None); |
| 257 | |
| 258 | // [0] |
| 259 | stack.push(0); |
| 260 | assert!(!stack.is_empty()); |
| 261 | assert_eq!(stack.peek(), Some(&0)); |
| 262 | |
| 263 | // [0, 1] |
| 264 | stack.push(1); |
| 265 | assert!(!stack.is_empty()); |
| 266 | assert_eq!(stack.peek(), Some(&1)); |
| 267 | |
| 268 | // [0] |
| 269 | assert_eq!(stack.pop(), Some(1)); |
| 270 | assert!(!stack.is_empty()); |
| 271 | assert_eq!(stack.peek(), Some(&0)); |
| 272 | |
| 273 | // [0, 2] |
| 274 | stack.push(2); |
| 275 | assert!(!stack.is_empty()); |
| 276 | assert_eq!(stack.peek(), Some(&2)); |
| 277 | |
| 278 | // [0, 2, 3] |
| 279 | stack.push(3); |
| 280 | assert!(!stack.is_empty()); |
| 281 | assert_eq!(stack.peek(), Some(&3)); |
| 282 | |
| 283 | // Take a snapshot of the current stack |
| 284 | // [0, 2, 3] |
| 285 | stack.snapshot(); |
| 286 | |
| 287 | // [0, 2] |
| 288 | assert_eq!(stack.pop(), Some(3)); |
| 289 | assert!(!stack.is_empty()); |
| 290 | assert_eq!(stack.peek(), Some(&2)); |
| 291 | |
| 292 | // Take a snapshot of the current stack |
| 293 | // [0, 2] |
| 294 | stack.snapshot(); |
| 295 | |
| 296 | // [0] |
| 297 | assert_eq!(stack.pop(), Some(2)); |
| 298 | assert!(!stack.is_empty()); |
| 299 | assert_eq!(stack.peek(), Some(&0)); |
| 300 | |
| 301 | // [] |
| 302 | assert_eq!(stack.pop(), Some(0)); |
| 303 | assert!(stack.is_empty()); |
| 304 | |
| 305 | // Test backtracking |
| 306 | // [0, 2] |
| 307 | stack.restore(); |