- add tests

- update packages
- update jest to use ts-jest
- refactor color generation to theme

jest.config.js

@@ -0,0 +1,6 @@
+/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */
+module.exports = {
+  preset: "ts-jest",
+  testEnvironment: "node",
+  modulePaths: ["<rootDir>/src"],
+};