test: adds jest for unit tests

Author: BenShelton

Diff for: .gitignore

@@ -10,3 +10,6 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 report.*.json
+
+# Test files
+tests/coverage

Diff for: jest.config.js

@@ -0,0 +1,14 @@
+module.exports = {
+  transform: {
+    '^.+\\.ts$': 'ts-jest',
+  },
+  collectCoverage: true,
+  collectCoverageFrom: ['src/**/*.ts'],
+  coverageDirectory: 'tests/coverage',
+  coveragePathIgnorePatterns: ['/node_modules/'],
+  coverageProvider: 'v8',
+  moduleFileExtensions: ['js', 'ts', 'vue'],
+  roots: ['<rootDir>/src/', '<rootDir>/tests/'],
+  testEnvironment: 'jest-environment-node',
+  testMatch: ['**/*.spec.ts'],
+}

Diff for: package.json

@@ -27,6 +27,7 @@
     "prepare": "yarn build",
     "commit": "cz",
     "build": "tsc",
+    "test": "jest",
     "semantic-release": "semantic-release"
   },
   "dependencies": {
@@ -35,6 +36,7 @@
   "devDependencies": {
     "@semantic-release/changelog": "^5.0.1",
     "@semantic-release/git": "^9.0.0",
+    "@types/jest": "^27.0.2",
     "@types/minimist": "^1.2.1",
     "@types/node": "^12.20.13",
     "@typescript-eslint/eslint-plugin": "^4.25.0",
@@ -44,8 +46,10 @@
     "eslint": "^7.27.0",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-prettier": "^3.4.0",
+    "jest": "^27.2.4",
     "prettier": "^2.3.0",
     "semantic-release": "^17.4.3",
+    "ts-jest": "^27.0.5",
     "typescript": "^4.2.4"
   },
   "peerDependencies": {