feat: handle error if cb does not return jimp

exuanbo · Nov 18, 2020 · ba9bae5 · ba9bae5
1 parent f0d77f9
commit ba9bae5
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Showing 2 changed files with 34 additions and 22 deletions.
diff --git a/__tests__/index.test.js b/__tests__/index.test.js
@@ -39,7 +39,7 @@ const compare = (stream, fixtureName, expectedName, done, expectedErr) => {
 }
 
 describe('gulp-jimp-wrapper', () => {
-  it('works for me', done => {
+  it('should just work', done => {
     compare(
       jimp(img => img.invert()),
       'original.jpg',
@@ -48,13 +48,25 @@ describe('gulp-jimp-wrapper', () => {
     )
   })
 
-  it('throws an error', done => {
+  it('should throw an error if argument is illegal', done => {
     compare(
       jimp('img => img.invert()'),
       'original.jpg',
       'invert.jpg',
       done,
-      `Argument \`img => img.invert()\` is not a function`
+      "Argument 'img => img.invert()' is not a function."
+    )
+  })
+
+  it('throws an error if callback does not return a Jimp instance', done => {
+    compare(
+      jimp(img => {
+        img.invert()
+      }),
+      'original.jpg',
+      'invert.jpg',
+      done,
+      'Jimp instance must be returned from your callback.'
     )
   })
 })
diff --git a/src/index.js b/src/index.js
@@ -15,46 +15,46 @@ const SUPPORTED_MIME_TYPES = {
   gif: 'image/gif'
 }
 
-const processImg = (img, cb) =>
-  new Promise((resolve, reject) => {
-    const extension = path.extname(img.path).split('.').pop()
-
-    jimp
-      .read(img.contents)
-      .then(cb)
-      .then(img => img.getBufferAsync(SUPPORTED_MIME_TYPES[extension]))
-      .then(data => resolve(data))
-      .catch(err => reject(err))
-  })
+const pluginError = msg => new PluginError(PLUGIN_NAME, msg)
+
+const processImage = async (img, cb, callback) => {
+  const extension = path.extname(img.path).split('.').pop()
+
+  const res = await jimp.read(img.contents).then(cb)
+  if (!(res instanceof jimp)) {
+    callback(pluginError('Jimp instance must be returned from your callback.'))
+    return
+  }
+
+  return res.getBufferAsync(SUPPORTED_MIME_TYPES[extension])
+}
 
-const jimpWrapper = cb =>
+const gulpJimp = cb =>
   through.obj(async function (img, _, callback) {
     if (img.isNull()) {
       callback(null, img)
       return
     }
 
     if (img.isStream()) {
-      callback(new PluginError(PLUGIN_NAME, 'Streaming not supported'))
+      callback(pluginError('Streaming not supported.'))
       return
     }
 
     if (typeof cb !== 'function') {
-      callback(
-        new PluginError(PLUGIN_NAME, `Argument \`${cb}\` is not a function`)
-      )
+      callback(pluginError(`Argument '${cb}' is not a function.`))
       return
     }
 
     try {
-      const data = await processImg(img, cb)
+      const data = await processImage(img, cb, callback)
       img.contents = Buffer.from(data)
       this.push(img)
     } catch (err) {
-      this.emit('error', new PluginError(PLUGIN_NAME, err))
+      this.emit('error', pluginError(err.message))
     }
 
     callback()
   })
 
-module.exports = jimpWrapper
+module.exports = gulpJimp