From f8ad1b25866c6e9c5a15356116f966f71477cc28 Mon Sep 17 00:00:00 2001
From: Steve Kinney <hello@stevekinney.net>
Date: Sun, 29 Sep 2024 16:55:08 -0600
Subject: [PATCH] Add utility belt example

---
 examples/utility-belt/package.json            | 25 +++++++++++++++++++
 examples/utility-belt/src/index.js            |  0
 examples/utility-belt/src/string-to-number.js | 14 +++++++++++
 .../utility-belt/src/string-to-number.test.js | 15 +++++++++++
 4 files changed, 54 insertions(+)
 create mode 100644 examples/utility-belt/package.json
 create mode 100644 examples/utility-belt/src/index.js
 create mode 100644 examples/utility-belt/src/string-to-number.js
 create mode 100644 examples/utility-belt/src/string-to-number.test.js

diff --git a/examples/utility-belt/package.json b/examples/utility-belt/package.json
new file mode 100644
index 0000000..e06f64a
--- /dev/null
+++ b/examples/utility-belt/package.json
@@ -0,0 +1,25 @@
+{
+  "name": "utility-belt",
+  "version": "1.0.0",
+  "main": "src/index.js",
+  "type": "module",
+  "scripts": {
+    "start": "vitest --ui",
+    "test": "vitest"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/stevekinney/testing-javascript.git"
+  },
+  "author": "Steve Kinney <hello@stevekinney.net>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/stevekinney/testing-javascript/issues"
+  },
+  "homepage": "https://github.com/stevekinney/testing-javascript#readme",
+  "devDependencies": {
+    "@vitest/ui": "^2.1.1",
+    "vite": "^5.4.5",
+    "vitest": "^2.1.1"
+  }
+}
diff --git a/examples/utility-belt/src/index.js b/examples/utility-belt/src/index.js
new file mode 100644
index 0000000..e69de29
diff --git a/examples/utility-belt/src/string-to-number.js b/examples/utility-belt/src/string-to-number.js
new file mode 100644
index 0000000..611af64
--- /dev/null
+++ b/examples/utility-belt/src/string-to-number.js
@@ -0,0 +1,14 @@
+/**
+ * Converts a string to a number or throws an error if the string is not a number.
+ * @param {string} value
+ * @returns {number} The number.
+ */
+export const stringToNumber = (value) => {
+  const number = Number(value);
+
+  if (isNaN(number)) {
+    throw new Error(`'${value}' cannot be parsed as a number.`);
+  }
+
+  return number;
+};
diff --git a/examples/utility-belt/src/string-to-number.test.js b/examples/utility-belt/src/string-to-number.test.js
new file mode 100644
index 0000000..95c252d
--- /dev/null
+++ b/examples/utility-belt/src/string-to-number.test.js
@@ -0,0 +1,15 @@
+import { describe, it, expect } from 'vitest';
+import { stringToNumber } from './string-to-number';
+
+describe('stringToNumber', () => {
+  it('converts a string to a number', () => {
+    expect(stringToNumber('42')).toBe(42);
+  });
+
+  it('throws an error if given a string that is not a number', () => {
+    const value = 'foo';
+    expect(() => stringToNumber(value)).toThrowError(
+      `cannot be parsed as a number`,
+    );
+  });
+});