Add build and test scripts

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/semver/semver?shareId=XXXX-XXXX-XXXX-XXXX).

.github/workflows/checks.yml

@@ -13,3 +13,5 @@ jobs:
           cache: 'npm'
       - run: npm ci
       - run: npm run lint
+      - run: npm run test
+      - run: npm run build

jest.config.js

@@ -0,0 +1,7 @@
+module.exports = {
+  testEnvironment: 'node',
+  verbose: true,
+  collectCoverage: true,
+  coverageDirectory: 'coverage',
+  testMatch: ['**/__tests__/**/*.js?(x)', '**/?(*.)+(spec|test).js?(x)'],
+};

package.json

@@ -5,7 +5,8 @@
   "main": "semver.md",
   "scripts": {
     "lint": "remark -qf semver.md",
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "jest",
+    "build": "tsc"
   },
   "repository": {
     "type": "git",
@@ -28,6 +29,8 @@
     "remark-cli": "^11.0.0",
     "remark-frontmatter": "^2.0.0",
     "remark-lint-mdash-style": "^1.1.1",
-    "remark-preset-lint-node": "^1.16.0"
+    "remark-preset-lint-node": "^1.16.0",
+    "jest": "^27.0.0",
+    "typescript": "^4.0.0"
   }
 }

tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "ES6",
+    "module": "commonjs",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "**/*.spec.ts"]
+}