test: use async functions in resolveConfig test

lib/__tests__/resolveConfig.test.js

@@ -5,37 +5,37 @@ const pluginWarnAboutFoo = require('./fixtures/plugin-warn-about-foo');
 const replaceBackslashes = require('../testUtils/replaceBackslashes');
 const stylelint = require('..');
 
-it('resolveConfig uses getConfigForFile to retrieve the config', () => {
+it('resolveConfig uses getConfigForFile to retrieve the config', async () => {
 	const filepath = replaceBackslashes(
 		path.join(__dirname, 'fixtures/getConfigForFile/a/b/foo.css'),
 	);
 
-	return stylelint.resolveConfig(filepath).then((result) => {
-		expect(result).toEqual({
-			plugins: [path.join(__dirname, '/fixtures/plugin-warn-about-foo.js')],
-			rules: {
-				'block-no-empty': [true],
-				'plugin/warn-about-foo': ['always'],
-			},
-			pluginFunctions: {
-				'plugin/warn-about-foo': pluginWarnAboutFoo.rule,
-			},
-		});
+	const config = await stylelint.resolveConfig(filepath);
+
+	expect(config).toEqual({
+		plugins: [path.join(__dirname, '/fixtures/plugin-warn-about-foo.js')],
+		rules: {
+			'block-no-empty': [true],
+			'plugin/warn-about-foo': ['always'],
+		},
+		pluginFunctions: {
+			'plugin/warn-about-foo': pluginWarnAboutFoo.rule,
+		},
 	});
 });
 
-it('config overrides should apply', () => {
+it('config overrides should apply', async () => {
 	const filepath = replaceBackslashes(
 		path.join(__dirname, 'fixtures/config-overrides/testPrintConfig/style.css'),
 	);
 
-	return stylelint.resolveConfig(filepath).then((result) => {
-		expect(result).toEqual({
-			rules: {
-				'block-no-empty': [true],
-				'color-named': ['never'],
-			},
-		});
+	const config = await stylelint.resolveConfig(filepath);
+
+	expect(config).toEqual({
+		rules: {
+			'block-no-empty': [true],
+			'color-named': ['never'],
+		},
 	});
 });