diff --git a/2022/day04-camp_cleanup/src/lib.rs b/2022/day04-camp_cleanup/src/lib.rs
new file mode 100644
index 0000000..0cc8eeb
--- /dev/null
+++ b/2022/day04-camp_cleanup/src/lib.rs
@@ -0,0 +1,67 @@
+use core::fmt::Display;
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum ParseError {
+    LineMalformed(String),
+}
+
+impl Display for ParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::LineMalformed(v) => write!(f, "Line is malformed: {v}"),
+        }
+    }
+}
+
+fn fully_contained(pair: &str) -> Result<bool, ParseError> {
+    let ((l1, r1), (l2, r2)) = parse_into_tuples(pair)?;
+    Ok(l1<=l2 && r1>=r2 || l2<=l1 && r2>=r1)
+}
+
+fn overlapping(pair: &str) -> Result<bool, ParseError> {
+    let ((l1, r1), (l2, r2)) = parse_into_tuples(pair)?;
+    Ok(l1<=l2 && r1>=l2 || l2<=l1 && r2>=l1)
+}
+
+fn parse_into_tuples(pair: &str) -> Result<((u32, u32), (u32, u32)), ParseError> {
+    if let Some((first, second)) = pair.split_once(',') {
+        if let Some ((l1, r1)) = first.split_once('-') {
+            if let Some((l2, r2)) = second.split_once('-') {
+                let l1 = l1.parse::<u32>().expect("Malformed ID: Not a number");
+                let l2 = l2.parse::<u32>().expect("Malformed ID: Not a number");
+                let r1 = r1.parse::<u32>().expect("Malformed ID: Not a number");
+                let r2 = r2.parse::<u32>().expect("Malformed ID: Not a number");
+                return Ok(((l1, r1), (l2, r2)));
+            }
+        }
+    }
+    Err(ParseError::LineMalformed(pair.to_string()))
+}
+
+pub fn run(input: &str) -> Result<(usize, usize), ParseError> {
+    let first = input.lines().map(fully_contained).collect::<Result<Vec<_>, _>>()?.iter().filter(|l| **l).count();
+    let second = input.lines().map(overlapping).collect::<Result<Vec<_>, _>>()?.iter().filter(|l| **l).count();
+    Ok((first, second))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs::read_to_string;
+
+    fn read_file(name: &str) -> String {
+        read_to_string(name).expect(&format!("Unable to read file: {name}")[..]).trim().to_string()
+    }
+
+    #[test]
+    fn test_sample() {
+        let sample_input = read_file("tests/sample_input");
+        assert_eq!(run(&sample_input), Ok((2, 4)));
+    }
+
+    #[test]
+    fn test_challenge() {
+        let challenge_input = read_file("tests/challenge_input");
+        assert_eq!(run(&challenge_input), Ok((560, 839)));
+    }
+}
diff --git a/2022/day04-camp_cleanup/src/main.rs b/2022/day04-camp_cleanup/src/main.rs
deleted file mode 100644
index cba4bff..0000000
--- a/2022/day04-camp_cleanup/src/main.rs
+++ /dev/null
@@ -1,61 +0,0 @@
-use std::fs;
-
-fn read_file(path: &str) -> String {
-    fs::read_to_string(path)
-        .expect("File not Found")
-}
-
-fn fully_contained(pair: &str) -> bool {
-    let ((l1, r1), (l2, r2)) = parse_into_tuples(pair);
-    l1<=l2 && r1>=r2 || l2<=l1 && r2>=r1
-}
-
-fn overlapping(pair: &str) -> bool {
-    let ((l1, r1), (l2, r2)) = parse_into_tuples(pair);
-    l1<=l2 && r1>=l2 || l2<=l1 && r2>=l1
-}
-
-fn parse_into_tuples(pair: &str) -> ((u32, u32), (u32, u32)) {
-    if let Some((first, second)) = pair.split_once(',') {
-        if let Some ((l1, r1)) = first.split_once('-') {
-            if let Some((l2, r2)) = second.split_once('-') {
-                let l1 = l1.parse::<u32>().expect("Malformed ID: Not a number");
-                let l2 = l2.parse::<u32>().expect("Malformed ID: Not a number");
-                let r1 = r1.parse::<u32>().expect("Malformed ID: Not a number");
-                let r2 = r2.parse::<u32>().expect("Malformed ID: Not a number");
-                return ((l1, r1), (l2, r2));
-            }
-        }
-    }
-    panic!("Malformatted input");
-}
-
-fn main() {
-    //let contents = read_file("sample_input");
-    let contents = read_file("input");
-
-    let fully_contained_count = contents.lines()
-        .filter(|l| fully_contained(l))
-        .count();
-
-    let overlapping_count = contents.lines()
-        .filter(|l| overlapping(l))
-        .count();
-
-    println!("For {fully_contained_count} pairs, one is fully contained within the other.");
-    println!("{overlapping_count} pairs have at least some overlap.")
-}
-
-#[test]
-fn sample_input() {
-    let contents = read_file("tests/sample_input");
-    assert_eq!(contents.lines().filter(|l| fully_contained(l)).count(), 2);
-    assert_eq!(contents.lines().filter(|l| overlapping(l)).count(), 4);
-}
-
-#[test]
-fn challenge_input() {
-    let contents = read_file("tests/input");
-    assert_eq!(contents.lines().filter(|l| fully_contained(l)).count(), 560);
-    assert_eq!(contents.lines().filter(|l| overlapping(l)).count(), 839);
-}
diff --git a/2022/day04-camp_cleanup/tests/input b/2022/day04-camp_cleanup/tests/challenge_input
similarity index 100%
rename from 2022/day04-camp_cleanup/tests/input
rename to 2022/day04-camp_cleanup/tests/challenge_input