diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..8b423bf
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,15 @@
+# https://editorconfig.org/
+
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.txt]
+trim_trailing_whitespace = unset
+insert_final_newline = unset
diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..6313b56
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+* text=auto eol=lf
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..869219e
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,24 @@
+name: "ci"
+
+on:
+    push:
+        branches: ["main"]
+    pull_request:
+        branches: ["main"]
+
+env:
+    CARGO_TERM_COLOR: "always"
+
+jobs:
+    ci:
+        runs-on: "ubuntu-latest"
+
+        steps:
+            - uses: "actions/checkout@v4"
+
+            - run: "rustc --version"
+
+            - run: "cargo build --verbose"
+            - run: "cargo test --verbose"
+            - run: "cargo clippy --verbose -- -D warnings"
+            - run: "cargo fmt -- --check"
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/day_1/Cargo.lock b/Cargo.lock
similarity index 76%
rename from day_1/Cargo.lock
rename to Cargo.lock
index 865acc3..64f913b 100644
--- a/day_1/Cargo.lock
+++ b/Cargo.lock
@@ -5,3 +5,7 @@ version = 3
 [[package]]
 name = "day_1"
 version = "1.0.0"
+
+[[package]]
+name = "day_2"
+version = "1.0.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..038916e
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,6 @@
+[workspace]
+members = [
+    "day_1",
+    "day_2",
+]
+resolver = "2"
diff --git a/README.md b/README.md
index 30ebb1d..20a350f 100644
--- a/README.md
+++ b/README.md
@@ -2,16 +2,15 @@
 
 ## About
 
-This repository contains my solutions to the [Advent of Code 2023](https://adventofcode.com/2023) challenges using the [Rust Programming Language](https://www.rust-lang.org/) v1.74.0.
-
-To run a solution (e.g. Day 1):
+This repository contains my solutions for the [Advent of Code 2023](https://adventofcode.com/2023) challenges implemented in the [Rust Programming Language](https://www.rust-lang.org/) v1.74.0.
 
 ```sh
-cd day_1
-cargo run
-```
+# Run the tests (input examples)
+cargo test
 
-**Note:** The solutions are not necessarily optimized for performance or readability, but rather for completing the challenge successfully.
+# Run a specific day's challenge (e.g. Day 1)
+cargo run --package day_1
+```
 
 ## License
 
diff --git a/day_1/src/main.rs b/day_1/src/main.rs
index c50a888..06ec0d4 100644
--- a/day_1/src/main.rs
+++ b/day_1/src/main.rs
@@ -10,7 +10,7 @@ fn part_1(input: &str) -> i32 {
             let first_digit = characters_digits.first().unwrap_or(&'0').to_owned();
             let last_digit = characters_digits.last().unwrap_or(&'0').to_owned();
             let number = format!("{}{}", first_digit, last_digit);
-            let number: i32 = number.parse().expect("Should parse as a number.");
+            let number: i32 = number.parse().expect("Should parse as a i32.");
             number
         })
         .sum()
@@ -64,15 +64,23 @@ fn part_2(input: &str) -> i32 {
 }
 
 fn main() {
-    let input_example1 = include_str!("../input_example_1.txt");
-    let input_example2 = include_str!("../input_example_2.txt");
     let input = include_str!("../input.txt");
-
-    println!("Answer Part 1 (example1): {}", part_1(input_example1));
-    println!("Answer Part 1 (example2): {}", part_1(input_example2));
+    println!("- Day 1: Trebuchet?! -");
     println!("Answer Part 1: {}", part_1(input));
-
-    println!("Answer Part 2 (example1): {}", part_2(input_example1));
-    println!("Answer Part 2 (example2): {}", part_2(input_example2));
     println!("Answer Part 2: {}", part_2(input));
 }
+
+#[cfg(test)]
+mod day_1_tests {
+    use super::*;
+
+    #[test]
+    fn test_part_1_example() {
+        assert_eq!(142, part_1(include_str!("../input_example_1.txt")));
+    }
+
+    #[test]
+    fn test_part_2_example() {
+        assert_eq!(281, part_2(include_str!("../input_example_2.txt")));
+    }
+}
diff --git a/day_2/.gitignore b/day_2/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/day_2/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/day_2/Cargo.toml b/day_2/Cargo.toml
new file mode 100644
index 0000000..e5fc844
--- /dev/null
+++ b/day_2/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "day_2"
+version = "1.0.0"
+edition = "2021"
+
+[dependencies]
diff --git a/day_2/README.md b/day_2/README.md
new file mode 100644
index 0000000..79cb764
--- /dev/null
+++ b/day_2/README.md
@@ -0,0 +1,7 @@
+# - Day 2 -
+
+Source: <https://adventofcode.com/2023/day/2>
+
+## Instructions - Part 1
+
+## Instructions - Part 2
diff --git a/day_2/src/main.rs b/day_2/src/main.rs
new file mode 100644
index 0000000..3eefe75
--- /dev/null
+++ b/day_2/src/main.rs
@@ -0,0 +1,18 @@
+fn part_1() -> i32 {
+    142
+}
+
+fn main() {
+    println!("- Day 2: Title -");
+    println!("Answer Part 1: {}", part_1());
+}
+
+#[cfg(test)]
+mod day_2_tests {
+    use super::*;
+
+    #[test]
+    fn test_part_1_example() {
+        assert_eq!(142, part_1());
+    }
+}