fix: 🐛 custom transformer not working with external src files

package.json

@@ -1,6 +1,6 @@
 {
   "name": "svelte-preprocess",
-  "version": "2.5.0",
+  "version": "2.5.1",
   "license": "MIT",
   "main": "src/index.js",
   "types": "src/index.d.ts",

src/utils.js

@@ -68,15 +68,15 @@ exports.addLanguageAlias = entries =>
   entries.forEach(entry => LANG_DICT.set(...entry))
 
 exports.getLanguage = (attributes, defaultLang) => {
-  let lang
+  let lang = defaultLang
 
-  if (attributes.src) {
+  if (attributes.lang) {
+    lang = attributes.lang
+  } else if (attributes.type) {
+    lang = attributes.type.replace(/^(text|application)\/(.*)$/, '$2')
+  } else if (attributes.src) {
     lang = attributes.src.match(/\.([^/.]+)$/)
     lang = lang ? lang[1] : defaultLang
-  } else {
-    lang = attributes.type
-      ? attributes.type.replace(/^(text|application)\/(.*)$/, '$2')
-      : attributes.lang || defaultLang
   }
 
   return {

test/fixtures/template.custom

@@ -0,0 +1 @@
+foo

test/index.test.js

@@ -263,10 +263,11 @@ describe('detect - mimetype', () => {
     { type: 'application/ld+json', parser: 'ld+json' },
     { type: 'text/some-other', parser: 'some-other' },
     { lang: 'stylus', parser: 'stylus' },
+    { src: '../foo.custom', lang: 'customLanguage', parser: 'customLanguage' },
   ]
-  MIMETYPES.forEach(({ type, lang, parser }) => {
-    it(`should detect ${type || lang} as ${parser}`, async () => {
-      expect(getLanguage({ type, lang }, 'javascript')).toEqual({
+  MIMETYPES.forEach(({ type, lang, src, parser }) => {
+    it(`should detect '${src || type || lang}' as '${parser}'`, async () => {
+      expect(getLanguage({ type, lang, src }, 'javascript')).toEqual({
         lang: parser,
         alias: parser,
       })
@@ -330,17 +331,19 @@ describe('external files', () => {
 
 describe('options', () => {
   it('should accept custom method for a transformer', async () => {
-    const input = `<template src="./fixtures/template.pug"></template>`
+    const input = `<template lang="customTransformer">${getFixtureContent(
+      'template.custom',
+    )}</template>`
     const opts = getPreprocess({
-      pug: (content, filename) => {
-        const code = require('pug').render(content, opts)
-        return {
-          code,
-        }
+      transformers: {
+        customTransformer({ content, filename }) {
+          content = content.replace('foo', 'bar')
+          return { code: content, map: null }
+        },
       },
     })
     const preprocessed = (await preprocess(input, opts)).trim()
-    expect(preprocessed).toBe(parsedMarkup)
+    expect(preprocessed).toBe('bar')
   })
 
   it('should accept an options object as transformer value', async () => {