add jest

jest.config.js

@@ -0,0 +1,6 @@
+module.exports = {
+  transform: {'^.+\\.ts?$': 'ts-jest'},
+  testEnvironment: 'node',
+  testRegex: '/tests/.*\\.(test|spec)?\\.(ts|tsx)$',
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node']
+};

package.json

@@ -5,7 +5,7 @@
   "main": "index.js",
   "scripts": {
     "dev": "yarn tsc -w",
-    "test": "echo \"Error: no test specified\" && exit 1",
+    "test": "yarn jest",
     "lint": "eslint . --ext .ts",
     "prettier-format": "prettier --config .prettierrc 'src/**/*.ts' --write"
   },
@@ -15,7 +15,12 @@
     "@typescript-eslint/eslint-plugin": "^5.21.0",
     "@typescript-eslint/parser": "^5.21.0",
     "eslint": "^8.14.0",
+    "jest": "^27.5.1",
+    "prettier": "^2.6.2",
+    "ts-jest": "^27.1.4",
     "typescript": "^4.6.3",
-    "prettier": "^2.6.2"
+    "@types/jest": "^27.4.1"
+  },
+  "dependencies": {
   }
 }