diff --git a/src/add.ts b/src/add.ts
new file mode 100644
index 0000000..8d9b8a2
--- /dev/null
+++ b/src/add.ts
@@ -0,0 +1,3 @@
+export function add(a: number, b: number): number {
+  return a + b;
+}
diff --git a/src/keep.ts b/src/keep.ts
new file mode 100644
index 0000000..f6bc2b3
--- /dev/null
+++ b/src/keep.ts
@@ -0,0 +1 @@
+export const keep = 1;
diff --git a/test/add.test.ts b/test/add.test.ts
new file mode 100644
index 0000000..ac2562b
--- /dev/null
+++ b/test/add.test.ts
@@ -0,0 +1,14 @@
+import { test, expect } from 'bun:test';
+import { add } from '../src/add';
+
+test('adds two numbers', () => {
+  expect(add(1, 2)).toBe(3);
+});
+
+test('adds negatives', () => {
+  expect(add(-1, -2)).toBe(-3);
+});
+
+test('is commutative', () => {
+  expect(add(2, 3)).toBe(add(3, 2));
+});