fix: pluginFactory preset accepts no argument

fix: unocss/unocss#1540

src/presets.ts

@@ -36,8 +36,8 @@ export function sourcePluginFactory(options: SourcePluginFactoryOptions) {
     transform: (source: string) => {
       const prefix = `
 let __unconfig_data;
-let __unconfig_stub = function (data) { __unconfig_data = data };
-__unconfig_stub.default = (data) => { __unconfig_data = data };
+let __unconfig_stub = function (data = {}) { __unconfig_data = data };
+__unconfig_stub.default = (data = {}) => { __unconfig_data = data };
 `
       const suffix = 'export default __unconfig_data;'
       let code = source

test/__snapshots__/run.test.ts.snap

@@ -1,6 +1,16 @@
 // Vitest Snapshot v1
 
-exports[`load > files 1`] = `6`;
+exports[`load > files 1`] = `
+[
+  "un.config.ts",
+  "un.config.mjs",
+  "un.config.json",
+  "package.json",
+  "rewrite.js",
+  "rewrite2.js",
+  "params.js",
+]
+`;
 
 exports[`load 1`] = `
 {

test/fixtures/rewrite2.js

@@ -0,0 +1,5 @@
+import a from 'stub'
+
+export default () => {
+  return a()
+}

test/run.test.ts

@@ -4,6 +4,7 @@ import { loadConfig } from '../src'
 import { sourcePackageJsonFields, sourcePluginFactory } from '../src/presets'
 
 it('load', async () => {
+  const cwd = resolve(__dirname, 'fixtures')
   const result = await loadConfig({
     sources: [
       {
@@ -17,20 +18,28 @@ it('load', async () => {
         files: 'rewrite.js',
         extensions: [],
       }),
+      sourcePluginFactory({
+        targetModule: 'stub',
+        files: 'rewrite2.js',
+        extensions: [],
+      }),
       sourcePluginFactory({
         targetModule: 'stub',
         files: 'params',
         parameters: ['include me', { param2: 'but not me' }],
       }),
     ],
-    cwd: resolve(__dirname, 'fixtures'),
+    cwd,
     defaults: {
       defaults: 'default',
       deep: { foo: 'hi' },
     },
     merge: true,
   })
 
-  expect(result.config).toMatchSnapshot()
-  expect(result.sources.length).toMatchSnapshot('files')
+  expect(result.config)
+    .toMatchSnapshot()
+
+  expect(result.sources.map(i => i.slice(cwd.length + 1)))
+    .toMatchSnapshot('files')
 })