day3 made testable

day3/src/main.rs

@@ -1,18 +1,11 @@
 #![warn(clippy::all, clippy::pedantic)]
 
-use std::fs::File;
-use std::io::{prelude::*, BufReader};
+use std::fs;
 
-fn main() -> std::io::Result<()> {
-    //Read in file
-    let file = File::open("input")?;
-    let reader = BufReader::new(file);
-
-    /*
-        let value = reader
+fn part1(input: &str) -> String {
+    input
         .lines()
         .map(|line| {
-                let line = line.unwrap();
             let (comp1, comp2) = line.split_at(line.len() / 2);
             let duplicate = comp2.chars().find(|c| comp1.contains(*c)).unwrap();
             match duplicate {
@@ -21,18 +14,18 @@ fn main() -> std::io::Result<()> {
                 _ => 0,
             }
         })
-            .sum::<i32>();
-        println!("Part 1: {value}");
-    */
-    //part 2
-    // fold the lines into groups of three
-    let value = reader
+        .sum::<i32>()
+        .to_string()
+}
+
+fn part2(input: &str) -> String {
+    input
         .lines()
         .fold(Vec::new(), |mut acc: Vec<Vec<String>>, line| {
             if acc.is_empty() || acc.last().unwrap().len() == 3 {
                 acc.push(Vec::new());
             }
-            acc.last_mut().unwrap().push(line.unwrap());
+            acc.last_mut().unwrap().push(line.to_owned());
             acc
         })
         .iter()
@@ -57,10 +50,41 @@ fn main() -> std::io::Result<()> {
                 _ => 0,
             }
         })
-        .sum::<i32>();
-    println!("Part 2: {value}");
+        .sum::<i32>()
+        .to_string()
+}
+
+fn main() -> std::io::Result<()> {
+    //Read in file
+    let file = fs::read_to_string("input")?;
+
+    // fold the lines into groups of three
+    println!("Part 1: {}", part1(&file));
+    println!("Part 2: {}", part2(&file));
     // find common letter in the groups
     //   find common letters in the first 2 then find the common in the third
     // sum the common letters
     Ok(())
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    const INPUT: &str = "vJrwpWtwJgWrhcsFMMfFFhFp
+jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
+PmmdzqPrVvPwwTWBwg
+wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
+ttgJtRGJQctTZtZT
+CrZsJsPPZsGzwwsLwLmpwMDw";
+
+    #[test]
+    fn part1_works() {
+        assert_eq!(part1(&INPUT), "157");
+    }
+
+    #[test]
+    fn part2_works() {
+        assert_eq!(part2(&INPUT), "70");
+    }
+}