Merge pull request #254 from atom/mb-async-on-will-save-hook

Wait for promises returned by `onWillSave` handlers before saving

Author: Max Brunsfeld

package-lock.json

@@ -50,7 +50,7 @@
     "delegato": "^1.0.0",
     "diff": "^2.2.1",
     "emissary": "^1.0.0",
-    "event-kit": "^2.1.0",
+    "event-kit": "^2.4.0",
     "fs-admin": "^0.1.4",
     "fs-plus": "^3.0.0",
     "grim": "^2.0.1",

package.json

@@ -238,6 +238,21 @@ describe('TextBuffer IO', () => {
       })
     })
 
+    it('waits for any promises returned by ::onWillSave observers', (done) => {
+      buffer.onWillSave(() => new Promise((resolve) => {
+        setTimeout(() => {
+          buffer.append(' - updated')
+          resolve()
+        }, 50)
+      }))
+
+      buffer.setText('Buffer contents')
+      buffer.save().then(() => {
+        expect(fs.readFileSync(filePath, 'utf8')).toBe('Buffer contents - updated')
+        done()
+      })
+    })
+
     describe('when the buffer is destroyed before the save completes', () => {
       it('saves the current contents of the buffer to the path', (done) => {
         buffer.setText('hello\n')

spec/text-buffer-io-spec.js

@@ -1561,11 +1561,13 @@ class TextBuffer
       destination = file.createWriteStream()
       directoryPromise = Promise.resolve()
 
-    @emitter.emit 'will-save', {path: filePath}
     @outstandingSaveCount++
 
     directoryPromise
-      .then => @buffer.save(destination, @getEncoding())
+      .then =>
+        @emitter.emitAsync 'will-save', {path: filePath}
+      .then =>
+        @buffer.save(destination, @getEncoding())
       .catch (error) =>
         if process.platform is 'darwin' and error.code is 'EACCES' and destination is filePath
           fsAdmin = require('fs-admin')