Restore behavior of reusing focused window for opened files

spec/integration/helpers/start-atom.coffee

@@ -2,7 +2,7 @@ path = require "path"
 temp = require("temp").track()
 remote = require "remote"
 async = require "async"
-{map, extend, once} = require "underscore-plus"
+{map, extend, once, difference} = require "underscore-plus"
 {spawn, spawnSync} = require "child_process"
 webdriverio = require "../../../build/node_modules/webdriverio"
 
@@ -67,6 +67,17 @@ buildAtomClient = (args, env) ->
         expect(result).toBe(true)
         cb(null)
 
+    .addCommand("waitForNewWindow", (fn, timeout, done) ->
+      @windowHandles()
+      .then(({value}) ->
+        return done() unless isRunning
+        oldWindowHandles = value
+        @call(-> fn.call(this))
+        .waitForWindowCount(oldWindowHandles.length + 1, 5000)
+        .then(({value}) ->
+          [newWindowHandle] = difference(value, oldWindowHandles)
+          @window(newWindowHandle, done))))
+
     .addCommand "startAnotherWindow", (args, env, done) ->
       @call ->
         if isRunning

spec/integration/startup-spec.coffee

@@ -53,39 +53,35 @@ describe "Starting Atom", ->
 
           # Opening a different directory creates a second window with no
           # tabs open.
-          .startAnotherWindow([otherTempDirPath], ATOM_HOME: AtomHome)
-          .waitForWindowCount(2, 5000)
-          .then(({value}) -> @window(value[1]))
+          .waitForNewWindow(->
+            @startAnotherWindow([otherTempDirPath], ATOM_HOME: AtomHome)
+          , 5000)
           .waitForExist("atom-workspace", 5000)
           .then((exists) -> expect(exists).toBe true)
           .waitForPaneItemCount(0, 1000)
 
     it "saves the state of closed windows", ->
-      runAtom [otherTempDirPath], {ATOM_HOME: AtomHome}, (client) ->
+      runAtom [tempDirPath], {ATOM_HOME: AtomHome}, (client) ->
         client
 
-          # Opening a file in another window creates another window with a tab
-          # open for that file.
+          # In a second window, opening a new buffer creates a new tab.
           .waitForExist("atom-workspace", 5000)
-          .startAnotherWindow([tempFilePath], ATOM_HOME: AtomHome)
-          .waitForWindowCount(2, 5000)
-          .then(({value}) -> @window(value[1]))
-          .waitForExist("atom-text-editor", 5000)
-          .click("atom-text-editor")
-          .execute(-> atom.workspace.getActiveTextEditor().getText())
-          .then(({value}) -> expect(value).toBe "This file was already here.")
+          .waitForNewWindow(->
+            @startAnotherWindow([otherTempDirPath], ATOM_HOME: AtomHome)
+          , 5000)
+          .waitForPaneItemCount(0, 3000)
+          .execute(-> atom.workspace.open())
+          .waitForPaneItemCount(1, 3000)
 
           # Closing that window and reopening that directory shows the
-          # previously-opened file.
+          # previously-created new buffer.
           .execute(-> atom.unloadEditorWindow())
           .close()
           .waitForWindowCount(1, 5000)
-          .startAnotherWindow([tempDirPath], ATOM_HOME: AtomHome)
-          .waitForWindowCount(2, 5000)
-          .then(({value}) -> @window(value[1]))
-          .waitForExist("atom-text-editor", 5000)
-          .execute(-> atom.workspace.getActiveTextEditor().getText())
-          .then(({value}) -> expect(value).toBe "This file was already here.")
+          .waitForNewWindow(->
+            @startAnotherWindow([otherTempDirPath], ATOM_HOME: AtomHome)
+          , 5000)
+          .waitForPaneItemCount(1, 5000)
 
     it "allows multiple project directories to be passed as separate arguments", ->
       runAtom [tempDirPath, otherTempDirPath], {ATOM_HOME: AtomHome}, (client) ->

src/browser/atom-application.coffee

@@ -351,9 +351,13 @@ class AtomApplication
     pathsToOpen = (fs.normalize(pathToOpen) for pathToOpen in pathsToOpen)
     locationsToOpen = (@locationForPathToOpen(pathToOpen) for pathToOpen in pathsToOpen)
 
-    unless pidToKillWhenClosed or newWindow # or devMode
+    unless pidToKillWhenClosed or newWindow
       existingWindow = @windowForPaths(pathsToOpen, devMode)
 
+    # Default to using the specified window or the last focused window
+    if pathsToOpen.every((pathToOpen) -> fs.statSyncNoException(pathToOpen).isFile?())
+      existingWindow ?= window ? @lastFocusedWindow
+
     if existingWindow?
       openedWindow = existingWindow
       openedWindow.openLocations(locationsToOpen)