Buffers emit 'before-save' and 'after-save' events during save

spec/app/buffer-spec.coffee

@@ -159,23 +159,39 @@ describe 'Buffer', ->
 
   describe ".save()", ->
     describe "when the buffer has a path", ->
-      filePath = null
+      [filePath, buffer] = []
 
       beforeEach ->
-        filePath = require.resolve('fixtures') + '/temp.txt'
-        expect(fs.exists(filePath)).toBeFalsy()
+        filePath = '/tmp/temp.txt'
+        fs.remove filePath if fs.exists(filePath)
+        buffer = new Buffer filePath
 
       afterEach ->
-        fs.remove filePath
+        fs.remove filePath if fs.exists(filePath)
 
       it "saves the contents of the buffer to the path", ->
-        buffer = new Buffer filePath
         buffer.setText 'Buffer contents!'
         buffer.save()
         expect(fs.read(filePath)).toEqual 'Buffer contents!'
 
+      it "fires beforeSave and afterSave events around the call to fs.write", ->
+        events = []
+        beforeSave1 = -> events.push('beforeSave1')
+        beforeSave2 = -> events.push('beforeSave2')
+        afterSave1 = -> events.push('afterSave1')
+        afterSave2 = -> events.push('afterSave2')
+
+        buffer.on 'before-save', beforeSave1
+        buffer.on 'before-save', beforeSave2
+        spyOn(fs, 'write').andCallFake -> events.push 'fs.write'
+        buffer.on 'after-save', afterSave1
+        buffer.on 'after-save', afterSave2
+
+        buffer.save()
+        expect(events).toEqual ['beforeSave1', 'beforeSave2', 'fs.write', 'afterSave1', 'afterSave2']
+
     describe "when the buffer no path", ->
-      it "throw an exception", ->
+      it "throws an exception", ->
         buffer = new Buffer
         expect(-> buffer.save()).toThrow()
 
@@ -313,6 +329,13 @@ describe 'Buffer', ->
         expect(buffer.lineForRow(5)).toBe '      foo = items.shift();'
         expect(buffer.lineForRow(6)).toBe '      foo < pivot ? left.push(foo) : right.push(current);'
 
+      it "allows the match to be replaced with the empty string", ->
+        buffer.scanInRange /current/g, [[4,0], [6,59]], (match, range, { replace }) ->
+          replace("")
+
+        expect(buffer.lineForRow(5)).toBe '       = items.shift();'
+        expect(buffer.lineForRow(6)).toBe '       < pivot ? left.push() : right.push(current);'
+
     describe "when the iterator calls the 'stop' control function", ->
       it "stops the traversal", ->
         ranges = []

src/app/buffer.coffee

@@ -142,7 +142,9 @@ class Buffer
 
   save: ->
     if not @getPath() then throw new Error("Tried to save buffer with no file path")
+    @trigger 'before-save'
     fs.write @getPath(), @getText()
+    @trigger 'after-save'
 
   saveAs: (path) ->
     @setPath(path)
@@ -185,6 +187,9 @@ class Buffer
 
     matches
 
+  scan: (regex, iterator) ->
+    @scanInRange(regex, @getRange(), iterator)
+
   scanInRange: (regex, range, iterator, reverse=false) ->
     range = Range.fromObject(range)
     global = regex.global
@@ -214,7 +219,7 @@ class Buffer
       replacementText = null
       iterator(match, range, { stop, replace })
 
-      if replacementText
+      if replacementText?
         @change(range, replacementText)
         lengthDelta += replacementText.length - matchLength unless reverse