Setup jest config and added example test.

jest.config.ts

@@ -0,0 +1,13 @@
+import type { Config } from '@jest/types'
+
+const config: Config.InitialOptions =
+{
+    transform:
+    {
+    '^.+\\.tsx?$': 'ts-jest',
+    },
+
+    collectCoverageFrom: ['src/*.ts'],
+}
+
+export default config