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

babel.config.js

@@ -1,14 +1,6 @@
-module.exports = {
-    presets: [
-        '@babel/typescript',
-        ['@babel/env', {
-            modules: false,
-            useBuiltIns: 'entry',
-            corejs: 3,
-        }],
-        '@babel/react',
-    ],
-    plugins: [
+module.exports = function (api) {
+    let targets = {};
+    const plugins = [
         'babel-plugin-macros',
         'styled-components',
         'react-hot-loader/babel',
@@ -19,5 +11,24 @@ module.exports = {
         '@babel/proposal-optional-chaining',
         '@babel/proposal-nullish-coalescing-operator',
         '@babel/syntax-dynamic-import',
-    ],
+    ];
+
+    if (api.env('test')) {
+        targets = { node: 'current' };
+        plugins.push('@babel/transform-modules-commonjs');
+    }
+
+    return {
+        plugins,
+        presets: [
+            '@babel/typescript',
+            ['@babel/env', {
+                modules: false,
+                useBuiltIns: 'entry',
+                corejs: 3,
+                targets,
+            }],
+            '@babel/react',
+        ]
+    };
 };