fix: PostCSS 8 plugin loading

package.json

@@ -72,11 +72,11 @@
     "memfs": "^3.2.0",
     "midas": "^2.0.3",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.0.1",
+    "postcss": "^8.1.1",
     "postcss-dark-theme-class": "^0.4.0",
     "postcss-import": "^12.0.1",
     "postcss-js": "^2.0.0",
-    "postcss-nested": "^4.2.3",
+    "postcss-nested": "^5.0.1",
     "postcss-short": "^5.0.0",
     "prettier": "^2.1.1",
     "sass": "^1.26.10",

src/utils.js

@@ -127,6 +127,8 @@ function pluginFactory() {
           const [name, options] = plugin;
 
           listOfPlugins.set(name, options);
+        } else if (plugin && typeof plugin === 'function') {
+          listOfPlugins.set(plugin);
         } else if (
           plugin &&
           Object.keys(plugin).length === 1 &&

test/config-autoload.test.js

@@ -75,7 +75,7 @@ describe('autoload config', () => {
     expect(loadedConfig.config.to).toEqual(
       './test/fixtures/config-autoload/js/object/expect/index.css'
     );
-    expect(Object.keys(loadedConfig.config.plugins).length).toEqual(2);
+    expect(Object.keys(loadedConfig.config.plugins).length).toEqual(4);
     expect(loadedConfig.filepath).toEqual(
       path.resolve(testDirectory, 'js/array', 'postcss.config.js')
     );

test/fixtures/config-autoload/js/array/postcss.config.js

@@ -12,7 +12,9 @@ module.exports = function (api) {
         {
           // Options
         }
-      ]
+      ],
+      require('postcss-nested'),
+      require('postcss-nested')({ /* Options */ }),
     ]
   }
 };