Some code cleanup, add jest coverage and begin using it for utility functions

jest.config.js

@@ -0,0 +1,28 @@
+const { pathsToModuleNameMapper } = require('ts-jest');
+const { compilerOptions } = require('./tsconfig');
+
+/** @type {import('ts-jest').InitialOptionsTsJest} */
+module.exports = {
+    preset: 'ts-jest',
+    globals: {
+        'ts-jest': {
+            isolatedModules: true,
+        },
+    },
+    moduleFileExtensions: ['js', 'ts', 'tsx', 'd.ts', 'json', 'node'],
+    moduleNameMapper: {
+        '\\.(jpe?g|png|gif|svg)$': '<rootDir>/resources/scripts/__mocks__/file.ts',
+        '\\.(s?css|less)$': 'identity-obj-proxy',
+        ...pathsToModuleNameMapper(compilerOptions.paths, {
+            prefix: '<rootDir>/',
+        }),
+    },
+    setupFilesAfterEnv: [
+        '<rootDir>/resources/scripts/setup-tests.ts',
+    ],
+    transform: {
+        '.*\\.[t|j]sx$': 'babel-jest',
+        '.*\\.ts$': 'ts-jest',
+    },
+    testPathIgnorePatterns: ['/node_modules/'],
+};