Fix tests

Author: rzhw

test/index.test.ts

@@ -17,10 +17,10 @@
 
 import { promises as fs } from 'fs';
 import postcss from 'postcss';
-import plugin, { Options } from '../src';
+import plugin = require('../src');
 import { toShortName } from '../src/minimal-renamer';
 
-async function run(input: string, options?: Options): Promise<postcss.Result> {
+async function run(input: string, options = {}): Promise<postcss.Result> {
   return await postcss([plugin(options)]).process(input, { from: undefined });
 }
 
@@ -36,7 +36,7 @@ function assertPostcss(result: postcss.Result, output: string): void {
 async function assertMapEquals(
   input: string,
   expected: { [key: string]: string },
-  options: Options = {}
+  options = {}
 ): Promise<void> {
   await run(input, {
     ...options,