diff --git a/2022/day05-supply_stacks/src/lib.rs b/2022/day05-supply_stacks/src/lib.rs
new file mode 100644
index 0000000..6bd7fea
--- /dev/null
+++ b/2022/day05-supply_stacks/src/lib.rs
@@ -0,0 +1,115 @@
+use core::fmt::Display;
+use std::num::ParseIntError;
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum ParseError {
+    InvalidInput,
+    ParseIntError(std::num::ParseIntError),
+}
+
+impl From<ParseIntError> for ParseError {
+    fn from(value: ParseIntError) -> Self {
+        Self::ParseIntError(value)
+    }
+}
+
+impl Display for ParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::InvalidInput => write!(f, "Invalid Input: Didn't contain two areas separated by an empty line"),
+            Self::ParseIntError(e) => write!(f, "Unable to parse into integer: {e}"),
+        }
+    }
+}
+
+enum Mode { SingleCrate, MultiCrate }
+
+#[derive(Clone)]
+struct State {
+    stacks: Vec<Vec<char>>,
+}
+
+impl From<&str> for State {
+    fn from(value: &str) -> Self {
+        let stack_count = (value.lines().last().unwrap().len() + 1) / 4;
+        let mut stacks = vec![Vec::new(); stack_count];
+        
+        value.lines().rev().skip(1).for_each(|line| {
+            (0..stack_count).for_each(|stack| {
+                let supply_crate = line.chars().nth(stack*4+1).unwrap_or(' ');
+                if supply_crate != ' ' {
+                    stacks[stack].push(supply_crate);
+                }
+            });
+        });
+        Self {
+            stacks,
+        }
+    }
+}
+
+impl State {
+    fn move_crates(&mut self, crate_count: usize, source: usize, destination: usize,) {
+        let source_length = self.stacks[source].len();
+        let move_stack = self.stacks[source].split_off(source_length.saturating_sub(crate_count));
+        self.stacks[destination].extend(move_stack.into_iter());
+    }
+
+    fn perform(&mut self, instruction: &str, operation_mode: Mode) -> Result<(), ParseError> {
+        let elements: Vec<&str> = instruction.split(' ').collect();
+        if elements.len()>4 {
+            let (crate_count, source, destination) = (elements[1].parse::<usize>()?, elements[3].parse::<usize>()?, elements[5].parse::<usize>()?);
+            match operation_mode {
+                Mode::SingleCrate => for _ in 0..crate_count {
+                        self.move_crates(1, source-1, destination-1);
+                    },
+                Mode::MultiCrate => {self.move_crates(crate_count, source-1, destination-1);},
+            }
+        }
+        Ok(())
+    }
+
+    fn top_str(&self) -> String {
+        self.stacks.iter()
+            .map(|stack| stack.last().unwrap_or(&' '))
+            .collect()
+    }
+}
+
+pub fn run(input: &str) -> Result<(String, String), ParseError> {
+    if let Some((initial_state, instructions)) = input.split_once("\n\n") {
+        let mut state_9000 = State::from(initial_state);
+        let mut state_9001 = state_9000.clone();
+        for instruction in instructions.lines() {
+            state_9000.perform(instruction, Mode::SingleCrate)?;
+            state_9001.perform(instruction, Mode::MultiCrate)?;
+        }
+        let first = state_9000.top_str();
+        let second = state_9001.top_str();
+        Ok((first, second))
+    } else {
+        Err(ParseError::InvalidInput)
+    }
+}
+
+#[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}")[..])
+    }
+
+    #[test]
+    fn test_sample() {
+        let sample_input = read_file("tests/sample_input");
+        assert_eq!(run(&sample_input), Ok(("CMZ".to_string(), "MCD".to_string())));
+    }
+
+    #[test]
+    fn test_challenge() {
+        let challenge_input = read_file("tests/challenge_input");
+        assert_eq!(run(&challenge_input), Ok(("QNHWJVJZW".to_string(), "BPCZJLFJW".to_string())));
+    }
+}
diff --git a/2022/day05-supply_stacks/src/main.rs b/2022/day05-supply_stacks/src/main.rs
deleted file mode 100644
index 12b5675..0000000
--- a/2022/day05-supply_stacks/src/main.rs
+++ /dev/null
@@ -1,109 +0,0 @@
-use std::fs;
-
-enum Mode { SingleCrate, MultiCrate }
-
-#[derive(Clone)]
-struct State {
-    stacks: Vec<Vec<char>>,
-}
-
-impl State {
-    fn from_initial(initial_state: &str) -> Self {
-        let stack_count = (initial_state.lines().last().unwrap().len() + 1) / 4;
-        let mut stacks = vec![Vec::new(); stack_count];
-        
-        for line in initial_state.lines().rev().skip(1) {
-            for stack in 0..stack_count {
-                let supply_crate = line.chars().nth(stack*4+1).unwrap();
-                if supply_crate != ' ' {
-                    stacks[stack].push(supply_crate);
-                }
-            }
-        }
-        State {
-            stacks,
-        }
-    }
-
-    fn move_crates(&mut self, crate_count: usize, source: usize, destination: usize,) {
-        let source_length = self.stacks[source].len();
-        let mut move_stack = self.stacks[source].split_off(source_length-crate_count);
-        self.stacks[destination].append(&mut move_stack);
-    }
-
-    fn perform(&mut self, instruction: &str, operation_mode: Mode) {
-        let elements: Vec<&str> = instruction.split(' ').collect();
-        if elements.len()>4 {
-            let (crate_count, source, destination) = (elements[1].parse::<usize>().unwrap(), elements[3].parse::<usize>().unwrap(), elements[5].parse::<usize>().unwrap());
-            match operation_mode {
-                Mode::SingleCrate => for _ in 0..crate_count {
-                        self.move_crates(1, source-1, destination-1);
-                    },
-                Mode::MultiCrate => {self.move_crates(crate_count, source-1, destination-1);},
-            }
-        }
-    }
-
-    fn top_str(&self) -> String {
-        self.stacks.iter()
-            .map(|stack| stack.last().unwrap_or(&' '))
-            .collect()
-    }
-}
-
-fn read_file(path: &str) -> String {
-    fs::read_to_string(path)
-        .expect("File not Found")
-}
-
-fn main() {
-    //let contents = read_file("sample_input");
-    let contents = read_file("input");
-    
-    if let Some((initial_state, instructions)) = contents.split_once("\n\n") {
-        let mut state_9000 = State::from_initial(initial_state);
-        let mut state_9001 = state_9000.clone();
-        for instruction in instructions.lines() {
-            state_9000.perform(instruction, Mode::SingleCrate);
-            state_9001.perform(instruction, Mode::MultiCrate);
-        }
-        println!("With CrateMover 9000, the top crates at the end are {}", state_9000.top_str());
-        println!("With CrateMover 9001, the top crates at the end are {}", state_9001.top_str());
-    }
-}
-
- #[test]
-fn sample_input() {
-    let contents = read_file("tests/sample_input");
-
-    if let Some((initial_state, instructions)) = contents.split_once("\n\n") {
-        let mut state_9000 = State::from_initial(initial_state);
-        let mut state_9001 = state_9000.clone();
-        for instruction in instructions.lines() {
-            state_9000.perform(instruction, Mode::SingleCrate);
-            state_9001.perform(instruction, Mode::MultiCrate);
-        }
-        assert_eq!(state_9000.top_str(), "CMZ");
-        assert_eq!(state_9001.top_str(), "MCD");
-    } else {
-        panic!("Unable to split input: {contents}");
-    }
-}
-
- #[test]
-fn challenge_input() {
-    let contents = read_file("tests/input");
-
-    if let Some((initial_state, instructions)) = contents.split_once("\n\n") {
-        let mut state_9000 = State::from_initial(initial_state);
-        let mut state_9001 = state_9000.clone();
-        for instruction in instructions.lines() {
-            state_9000.perform(instruction, Mode::SingleCrate);
-            state_9001.perform(instruction, Mode::MultiCrate);
-        }
-        assert_eq!(state_9000.top_str(), "QNHWJVJZW");
-        assert_eq!(state_9001.top_str(), "BPCZJLFJW");
-    } else {
-        panic!("Unable to split input: {contents}");
-    }
-}
diff --git a/2022/day05-supply_stacks/tests/input b/2022/day05-supply_stacks/tests/challenge_input
similarity index 100%
rename from 2022/day05-supply_stacks/tests/input
rename to 2022/day05-supply_stacks/tests/challenge_input