build(package): update dtslint and fix type errors

.eslintrc.json

@@ -1,15 +1,20 @@
 {
   "env": {
-    "jest": true,
-    "node": true
+    "node": true,
+    "jest": true
   },
-  "extends": "eslint:recommended",
+  "extends": ["eslint:recommended", "plugin:@typescript-eslint/recommended"],
+  "parser": "@typescript-eslint/parser",
   "parserOptions": {
-    "ecmaVersion": 6,
+    "ecmaVersion": 12,
     "sourceType": "module"
   },
-  "plugins": ["prettier"],
+  "plugins": ["@typescript-eslint", "prettier"],
   "rules": {
+    "@typescript-eslint/no-unused-vars": "error",
+    "@typescript-eslint/no-var-requires": "off",
+    "no-console": "error",
+    "no-debugger": "error",
     "prettier/prettier": "error"
   }
 }

__tests__/index.test.js

@@ -30,6 +30,7 @@ describe('invalid cases', () => {
 
 describe('iterator', () => {
   it('returns null', () => {
+    // eslint-disable-next-line @typescript-eslint/no-empty-function
     expect(parse('color: #foo;', () => {})).toBe(null);
   });
 

__tests__/types/index.ts

@@ -0,0 +1,16 @@
+import StyleToObject from 'style-to-object';
+
+// $ExpectType { [name: string]: string; } | null
+StyleToObject('color: red');
+
+// @ts-expect-error: Expected 1-2 arguments, but got 0.
+StyleToObject();
+
+// @ts-expect-error: Argument of type 'null' is not assignable to parameter of type 'string'.
+StyleToObject(null);
+
+// @ts-expect-error: Argument of type 'number' is not assignable to parameter of type 'string'.
+StyleToObject(42);
+
+// @ts-expect-error: Argument of type 'boolean' is not assignable to parameter of type 'string'.
+StyleToObject(true);