Support for specifying plugins in Array

jest.config.ts

@@ -0,0 +1,12 @@
+export default {
+  roots: [
+    '<rootDir>'
+  ],
+  testMatch: [
+    '**/__tests__/**/*.+(ts|tsx|js)',
+    '**/?(*.)+(spec|test).+(ts|tsx|js)'
+  ],
+  transform: {
+    '^.+\\.(ts|tsx)$': 'ts-jest'
+  }
+}

package.json

@@ -11,9 +11,10 @@
     "build": "siroc build",
     "prepublishOnly": "yarn build",
     "dev": "nuxt dev test/fixture",
+    "dev:legacy": "nuxt dev -c nuxt.config.legacy.ts test/fixture",
     "lint": "eslint --ext .ts .",
     "release": "yarn test && standard-version && git push --follow-tags && npm publish",
-    "test": "yarn lint"
+    "test": "yarn build && jest"
   },
   "dependencies": {
     "autoprefixer": "^10.2.5",
@@ -27,9 +28,13 @@
   },
   "devDependencies": {
     "@nuxtjs/eslint-config-typescript": "^5.0.0",
+    "@types/jest": "^26.0.23",
     "eslint": "^7.22.0",
+    "jest": "^27.0.5",
     "nuxt": "^2.15.3",
     "siroc": "^0.8.0",
-    "standard-version": "^9.1.1"
+    "standard-version": "^9.1.1",
+    "ts-jest": "^27.0.3",
+    "ts-node": "^10.0.0"
   }
 }

src/index.ts

@@ -20,9 +20,13 @@ function postcss8Module () {
     return [item].concat(arr.filter(el => el !== item))
   }
   nuxt.options.build.postcss = defu(nuxt.options.build.postcss, {
-    plugins: {
-      autoprefixer: {}
-    },
+    plugins: Array.isArray(nuxt.options.build.postcss.plugins)
+      ? [
+          ['autoprefixer', {}]
+        ]
+      : {
+          autoprefixer: {}
+        },
     order (names) {
       names = moveToFirst(names, 'postcss-url')
       names = moveToFirst(names, 'postcss-import')

test/__tests__/index.spec.ts

@@ -0,0 +1,52 @@
+const postcss8Module = require('../../dist')
+
+describe('@nuxt/postcss8', () => {
+  const mockNuxt: any = (() => {
+    const nuxt: any = {}
+    nuxt.constructor.version = '2.15.3'
+    nuxt.options = {
+      build: {
+        postcss: {}
+      }
+    }
+
+    return { nuxt }
+  })()
+
+  describe.each([
+    [
+      'plugins are specified by object',
+      {
+        pluginA: {},
+        pluginB: {}
+      },
+      {
+        pluginA: {},
+        pluginB: {},
+        autoprefixer: {}
+      }
+    ],
+    [
+      'plugins are specified by array',
+      [
+        ['pluginA', {}],
+        ['pluginB', {}]
+      ],
+      [
+        ['autoprefixer', {}],
+        ['pluginA', {}],
+        ['pluginB', {}]
+      ]
+    ]
+  ])('when %s', (_case: string, pluginsInDefaults: object, pluginsExpected: object) => {
+    describe(`defaults are ${JSON.stringify(pluginsInDefaults)}`, () => {
+      it(`should overwrite build.postcss.plugins to ${JSON.stringify(pluginsExpected)}`, () => {
+        mockNuxt.nuxt.options.build.postcss = { plugins: pluginsInDefaults }
+        mockNuxt.module = postcss8Module
+        mockNuxt.module()
+
+        expect(mockNuxt.nuxt.options.build.postcss.plugins).toStrictEqual(pluginsExpected)
+      })
+    })
+  })
+})

test/fixture/mock-plugin.js

@@ -0,0 +1,7 @@
+
+module.exports = () => {
+  return {
+    postcssPlugin: 'mock-plugin'
+  }
+}
+module.exports.postcss = true

test/fixture/nuxt.config.legacy.ts

@@ -0,0 +1,17 @@
+import nuxtpostcss8 from '../../src'
+
+export default {
+  buildModules: [
+    nuxtpostcss8
+  ],
+  css: [
+    '~/css/app.css'
+  ],
+  build: {
+    postcss: {
+      plugins: {
+        'mock-plugin': require('./mock-plugin')
+      }
+    }
+  }
+}

test/fixture/nuxt.config.ts

@@ -6,5 +6,12 @@ export default {
   ],
   css: [
     '~/css/app.css'
-  ]
+  ],
+  build: {
+    postcss: {
+      plugins: [
+        require('./mock-plugin')
+      ]
+    }
+  }
 }