finished ch12.4

minigrep/src/lib.rs

@@ -23,7 +23,39 @@ impl Config {
 pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
     let contents = fs::read_to_string(config.file_path)?;
 
-    println!("With text:\n{contents}")
+    // refactor 10
+    // println!("With text:\n{contents}")
+
+    for line in search(&config.query, &contents) {
+        println!("{line}");
+    }
 
     Ok(())
-}
+}
+
+pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+    // original that only can fail
+    // vec![]
+
+    for line in contents.lines() {
+        if line.contains(query) {
+            // do something with line
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn one_result() {
+        let query = "duct";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.";
+
+        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
+    }
+}

minigrep/src/main.rs

@@ -30,12 +30,13 @@ fn main() {
     //     process::exit(1);
     // });
 
-
-    println!("Searching for {}", config.query);
-    println!("In the file {}", config.file_path);
+    // refactor 10
+    // println!("Searching for {}", config.query);
+    // println!("In the file {}", config.file_path);
 
     // refactor 8
     if let Err(e) = minigrep::run(config) {
+        // needed for helping the user
         println!("Application error: {e}");
         process::exit(1);
     }