feat: support handling .svelte files

package.json

@@ -49,8 +49,27 @@
     "nps": "^5.7.1",
     "nps-utils": "^1.3.0",
     "prettier-eslint-cli": "^8.0.0",
+    "prettier-plugin-svelte": "^3.1.2",
     "rimraf": "^5.0.5",
-    "strip-indent": "^3.0.0"
+    "strip-indent": "^3.0.0",
+    "svelte": "^4.2.9",
+    "svelte-eslint-parser": "^0.33.1"
+  },
+  "peerDependencies": {
+    "prettier-plugin-svelte": "^3.1.2",
+    "svelte": "^4.2.9",
+    "svelte-eslint-parser": "^0.33.1"
+  },
+  "peerDependenciesMeta": {
+    "prettier-plugin-svelte": {
+      "optional": true
+    },
+    "svelte": {
+      "optional": true
+    },
+    "svelte-eslint-parser": {
+      "optional": true
+    }
   },
   "engines": {
     "node": ">=16.10.0"

src/__tests__/index.js

@@ -193,6 +193,19 @@ const tests = [
     output:
       '<template>\n  <div></div>\n</template>\n<script>\nfunction foo () {\n  return "foo";\n}\n</script>\n<style></style>'
   },
+  {
+    title: 'Svelte example',
+    input: {
+      prettierOptions: {
+          plugins: ['prettier-plugin-svelte'],
+          overrides: [{ files: '*.svelte', options: { parser: 'svelte' } }]
+        },
+      text: '<script>\nfunction foo() { return "foo" }\n</script>\n  <div>test</div>\n<style>\n</style>',
+      filePath: path.resolve('./test.svelte')
+    },
+    output:
+      '<script>\n  function foo() {\n    return "foo";\n  }\n</script>\n\n<div>test</div>\n\n<style>\n</style>'
+  },
   {
     title: 'GraphQL example',
     input: {

src/index.js

@@ -56,6 +56,7 @@ async function format(options) {
  *  `r.output` is the formatted string and `r.messages` is an array of
  *  message specifications from eslint.
  */
+// eslint-disable-next-line complexity
 async function analyze(options) {
   const { logLevel = getDefaultLogLevel() } = options;
   logger.setLevel(logLevel);
@@ -112,7 +113,8 @@ async function analyze(options) {
     '.ts',
     '.tsx',
     '.mjs',
-    '.vue'
+    '.vue',
+    '.svelte'
   ];
   const fileExtension = path.extname(filePath || '');
 
@@ -138,6 +140,10 @@ async function analyze(options) {
     formattingOptions.eslint.parser ||= require.resolve('vue-eslint-parser');
   }
 
+  if (['.svelte'].includes(fileExtension)) {
+    formattingOptions.eslint.parser ||= require.resolve('svelte-eslint-parser');
+  }
+
   const eslintFix = await createEslintFix(formattingOptions.eslint, eslintPath);
 
   if (prettierLast) {