Code and tests

tests/add.test.js

@@ -1,4 +1,5 @@
 import { describe, it, expect } from "vitest";
+import { add } from "../src/add";
 
 describe("Test add function", () => {
   it("should add two positive numbers", () => {
@@ -8,9 +9,29 @@ describe("Test add function", () => {
     const expected = 3;
 
     // Act
-    const result = a + b;
+    const result = add(a, b);
 
     // Assert
     expect(result).toBe(expected);
   });
+
+  it("should add two negative numbers", () => {
+    const x = -5;
+    const y = -6;
+    const expected = -11;
+
+    const res = add(x, y);
+
+    expect(res).toBe(expected);
+  });
+
+  it("should add a positive and a negative number", () => {
+    const firstNum = -7;
+    const secondNum = 10;
+    const expected = 3;
+
+    const res = add(firstNum, secondNum);
+
+    expect(res).toBe(expected);
+  });
 });