Added jest along with a jest test.

Author: dlabaj

jest.config.ts

@@ -0,0 +1,14 @@
+import type {Config} from 'jest';
+
+const config: Config = {
+    preset: 'ts-jest',
+    testEnvironment: 'node',
+    transform: {
+        ".ts": ["ts-jest", { tsconfig: "./tsconfig.jest.json" }]
+      },
+    roots: ['<rootDir>/src'],
+    testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.[jt]sx?$',
+    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+};
+
+export default config;