feat: support ESM config files (#414)

Uses `import` for dynamic module imports allowing you to use ESM as a config file.

Also lets you return a function that returns a promise to get the config in case you need to do some async work to retrieve it from somewhere.

Fixes #413

.gitignore

@@ -13,3 +13,4 @@ node_modules
 coverage.lcov
 yarn-error.log
 dist
+.tmp

cli.js

@@ -5,7 +5,7 @@ import path from 'path'
 import sade from 'sade'
 import kleur from 'kleur'
 import { fileURLToPath } from 'url'
-import { lilconfigSync } from 'lilconfig'
+import { lilconfig } from 'lilconfig'
 import mergeOptions from 'merge-options'
 import { runnerOptions } from './src/utils/index.js'
 import UvuRunner from './src/runner-uvu.js'
@@ -105,6 +105,22 @@ const sade2 = new Proxy(sade('playwright-test [files]', true), {
   },
 })
 
+const loadEsm = async (/** @type {string} */ filepath) => {
+  /** @type {any} */
+  const res = await import(filepath)
+
+  if (res.default) {
+    return res.default
+  }
+
+  return res
+}
+
+const configLoaders = {
+  '.js': loadEsm,
+  '.mjs': loadEsm,
+}
+
 sade2
   .version(version)
   .describe(
@@ -143,20 +159,29 @@ sade2
     'File extensions allowed in the bundle.  (default js,cjs,mjs,ts,tsx)'
   )
   .option('--config', 'Path to the config file')
-  .action((input, opts) => {
+  .action(async (input, opts) => {
     let config
     try {
       if (opts.config) {
-        config = lilconfigSync('playwright-test').load(
-          path.resolve(opts.config)
-        )
+        config = await lilconfig('playwright-test', {
+          loaders: configLoaders,
+        }).load(path.resolve(opts.config))
       } else {
-        config = lilconfigSync('playwright-test').search()
+        config = await lilconfig('playwright-test', {
+          loaders: configLoaders,
+        }).search()
         if (!config) {
-          config = lilconfigSync('pw-test').search()
+          config = await lilconfig('pw-test', {
+            loaders: configLoaders,
+          }).search()
         }
       }
 
+      // if the supplied config module was a function, invoke it
+      if (config && typeof config.config === 'function') {
+        config.config = await config.config()
+      }
+
       let Runner
 
       switch (opts.runner) {

mocks/sw/sw.config.mjs

@@ -0,0 +1,10 @@
+const path = require('path')
+
+export default {
+  buildSWConfig: {
+    inject: [path.join(__dirname, 'sw-globals.js')],
+  },
+  afterTests: () => {
+    console.log('AFTER')
+  }
+}

mocks/sw/sw.function.config.mjs

@@ -0,0 +1,12 @@
+const path = require('path')
+
+export default function () {
+  return {
+    buildSWConfig: {
+      inject: [path.join(__dirname, 'sw-globals.js')],
+    },
+    afterTests: () => {
+      console.log('AFTER')
+    }
+  }
+}

mocks/sw/sw.promise.config.mjs

@@ -0,0 +1,10 @@
+const path = require('path')
+
+export default Promise.resolve({
+  buildSWConfig: {
+    inject: [path.join(__dirname, 'sw-globals.js')],
+  },
+  afterTests: () => {
+    console.log('AFTER')
+  }
+})

test.js

@@ -100,6 +100,42 @@ describe('mocha', function () {
 
     is(proc.exitCode, 0, 'exit code')
   })
+
+  it('supports esm config files', async () => {
+    const proc = await execa('./cli.js', [
+      'mocks/sw/sw-test.js',
+      '--sw',
+      'mocks/sw/sw.js',
+      '--config',
+      'mocks/sw/sw.config.mjs',
+    ])
+
+    is(proc.exitCode, 0, 'exit code')
+  })
+
+  it('supports esm config files that return promises', async () => {
+    const proc = await execa('./cli.js', [
+      'mocks/sw/sw-test.js',
+      '--sw',
+      'mocks/sw/sw.js',
+      '--config',
+      'mocks/sw/sw.promise.config.mjs',
+    ])
+
+    is(proc.exitCode, 0, 'exit code')
+  })
+
+  it('supports esm config files that return functions', async () => {
+    const proc = await execa('./cli.js', [
+      'mocks/sw/sw-test.js',
+      '--sw',
+      'mocks/sw/sw.js',
+      '--config',
+      'mocks/sw/sw.function.config.mjs',
+    ])
+
+    is(proc.exitCode, 0, 'exit code')
+  })
 })
 
 describe('tape', function () {