Update Ch15

projects/limit_tracker/src/lib.rs

@@ -25,14 +25,11 @@ where
 
         let percentage_of_max = self.value as f64 / self.max as f64;
 
-        if percentage_of_max >= 1.0 {
-            self.messenger.send("出错：你已超出你的配额！");
-        } else if percentage_of_max >= 0.9 {
-            self.messenger
-                .send("紧急警告：你已用掉你配额的 90% ！");
-        } else if percentage_of_max >= 0.75 {
-            self.messenger
-                .send("警告：你已用掉你配额的 75% ！");
+        match percentage_of_max {
+            max if max >= 1.0 => self.messenger.send("出错：你已超出你的配额！"),
+            max if max >= 0.9 => self.messenger.send("紧急警告：你已用掉你配额的 90% ！"),
+            max if max >= 0.75 => self.messenger.send("警告：你已用掉你配额的 75% ！"),
+            _ => {},
         }
     }
 }

projects/pattern_syntax_demo/src/main.rs

@@ -10,8 +10,17 @@ fn main() {
             id: id_variable @ 3..=7,
         } => println! ("找到位于范围内的一个 id: {}", id_variable),
         Message::Hello { id: 10..=12 } => {
-            println! ("找到位于另一范围的一个 {}", id);
+            println! ("找到位于另一范围的一个 id");
         },
         Message::Hello { id } => println! ("找到别的一个 id: {}", id),
     }
+
+    let level = 0.8;
+
+    match level {
+        l if l >= 1.0 => println! ("超出额度"),
+        l if l >= 0.9 => println! ("超出 90% 额度"),
+        l if l >= 0.75 => println! ("超出 75% 额度"),
+        _ => (),
+    }
 }

src/Ch15_Smart_Pointers.md

@@ -857,7 +857,38 @@ Rust 没有像其他语言那样拥有对象，Rust 也没有像其他一些语
 文件名：`src/lib.rs`
 
 ```rust
-{{#include ../projects/limit_tracker/src/lib.rs:40:}}
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct MockMessenger {
+        sent_messages: Vec<String>,
+    }
+
+    impl MockMessenger {
+        fn new() -> MockMessenger {
+            MockMessenger {
+                sent_messages: vec![],
+            }
+        }
+    }
+
+    impl Messenger for MockMessenger {
+        fn send(&self, message: &str) {
+            self.sent_messages.push(String::from(message));
+        }
+    }
+
+    #[test]
+    fn it_sends_an_over_75_percent_warning_message() {
+        let mock_messenger = MockMessenger::new();
+        let mut limit_tracker = LimitTracker::new(&mock_messenger, 100);
+
+        limit_tracker.set_value(80);
+
+        assert_eq!(mock_messenger.sent_messages.len(), 1);
+    }
+}
 ```
 
 *清单 15-21：试图实现一个借用检查器不允许的 `MockMessenger`*