test: add basic spec and ci for jest

.github/workflows/tests.yml

@@ -0,0 +1,15 @@
+name: tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - run: npm ci
+    - run: npm test

README.md

@@ -11,6 +11,10 @@
     <img src="https://github.com/bcanseco/github-contribution-graph-action/workflows/build/badge.svg">
   </a>
 
+  <a href="https://github.com/bcanseco/github-contribution-graph-action/actions?query=workflow%3Atests">
+    <img src="https://github.com/bcanseco/github-contribution-graph-action/workflows/tests/badge.svg">
+  </a>
+
   <a href="https://github.com/bcanseco/github-contribution-graph-action/actions?query=workflow%3Aaudit">
     <img src="https://github.com/bcanseco/github-contribution-graph-action/workflows/audit/badge.svg">
   </a>

package.json

@@ -2,7 +2,8 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "start": "node --experimental-top-level-await --experimental-specifier-resolution=node -r dotenv-safe/config src"
+    "start": "node --experimental-top-level-await --experimental-specifier-resolution=node -r dotenv-safe/config src",
+    "test": "node --experimental-vm-modules node_modules/jest/bin/jest"
   },
   "engines": {
     "node": ">=14.3.0"
@@ -11,5 +12,9 @@
     "date-fns": "^2.14.0",
     "dotenv-safe": "^8.2.0",
     "simple-git": "^2.5.0"
+  },
+  "devDependencies": {
+    "@types/jest": "^25.2.3",
+    "jest": "^26.0.1"
   }
 }

src/random/index.js

@@ -13,4 +13,4 @@ export const getRandomInt = (min, max) => {
   }
 
   return Math.floor(Math.random() * (max - min + 1)) + min;
-}
+};

src/random/index.spec.js

@@ -0,0 +1,24 @@
+import {getRandomInt} from '.';
+
+it('should disallow negative values', () => {
+  expect(() => getRandomInt(-5, 1)).toThrow();
+  expect(() => getRandomInt(-5, -1)).toThrow();
+  expect(() => getRandomInt(1, -5)).toThrow();
+});
+
+it('should disallow min greater than max', () => {
+  expect(() => getRandomInt(1, 2)).not.toThrow();
+  expect(() => getRandomInt(1, 1)).not.toThrow();
+  expect(() => getRandomInt(1, 0)).toThrow();
+  expect(() => getRandomInt(0, 0)).not.toThrow();
+});
+
+it('should work with numeric strings', () => {
+  expect(() => getRandomInt(1, 5)).not.toThrow();
+  expect(() => getRandomInt('1', '5')).not.toThrow();
+});
+
+it('should be inclusive on min and max', () => {
+  expect(getRandomInt(0, 0)).toEqual(0);
+  expect(getRandomInt(1, 1)).toEqual(1);
+});