tests: setup unit tests, and add firsts

.eslintrc.cjs

@@ -1,18 +1,19 @@
 module.exports = {
   root: true,
-  env: { browser: true, es2020: true },
+  env: { browser: true, es2021: true },
   extends: [
-    'eslint:recommended',
-    'plugin:@typescript-eslint/recommended',
-    'plugin:react-hooks/recommended',
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:react-hooks/recommended",
+    "prettier",
   ],
-  ignorePatterns: ['dist', '.eslintrc.cjs'],
-  parser: '@typescript-eslint/parser',
-  plugins: ['react-refresh'],
+  ignorePatterns: ["dist", ".eslintrc.cjs"],
+  parser: "@typescript-eslint/parser",
+  plugins: ["react", "react-refresh", "prettier"],
   rules: {
-    'react-refresh/only-export-components': [
-      'warn',
+    "react-refresh/only-export-components": [
+      "warn",
       { allowConstantExport: true },
     ],
   },
-}
+};

.gitignore

@@ -10,6 +10,7 @@ lerna-debug.log*
 node_modules
 dist
 dist-ssr
+coverage
 *.local
 
 # Editor directories and files
@@ -23,4 +24,4 @@ dist-ssr
 *.sln
 *.sw?
 
-.env
+.env

.prettierrc.cjs

@@ -0,0 +1,8 @@
+const config = {
+  trailingComma: 'es5',
+  tabWidth: 2,
+  semi: true,
+  singleQuote: false,
+};
+
+module.exports = config;