conditionally spawn xvfb more intelligently

Author: brian-mann

lib/commands/open.coffee

@@ -26,9 +26,8 @@ class Open
       args.push("--port", options.port)
 
     utils.spawn(args, {
-      xvfb: false
       detached: true
       stdio: ["ignore", "ignore", "ignore"]
     })
 
-module.exports = Open
+module.exports = Open

lib/utils.coffee

@@ -123,6 +123,13 @@ module.exports = {
     .then(fn)
     .catch(fn)
 
+  needsXfvb: ->
+    ## do we need xvfb to run?
+    ##
+    ## we only need xvfb on linux
+    ## and when no process.env.DISPLAY is not
+    os.platform() is "linux" and not process.env.DISPLAY
+
   exec: (args, options = {}) ->
     e = null
 
@@ -149,10 +156,11 @@ module.exports = {
   spawn: (args, options = {}) ->
     args = [].concat(args)
 
+    needsXfvb = @needsXfvb()
+
     _.defaults options,
       verify: false
       detached: false
-      xvfb: os.platform() is "linux"
       stdio: [process.stdin, process.stdout, "ignore"]
 
     spawn = =>
@@ -162,7 +170,7 @@ module.exports = {
           return process.exit()
 
         sp = cp.spawn pathToCypress, args, options
-        if options.xvfb
+        if needsXfvb
           ## make sure we close down xvfb
           ## when our spawned process exits
           sp.on "close", @stopXvfb
@@ -177,8 +185,8 @@ module.exports = {
 
         return sp
 
-    if options.xvfb
+    if needsXfvb
       @startXvfb().then(spawn)
     else
       spawn()
-}
+}

test/commands/open_spec.coffee

@@ -41,7 +41,6 @@ describe "Open", ->
 
       pathToProject = path.resolve(process.cwd(), "path/to/project")
       expect(@spawn).to.be.calledWith(["--project", pathToProject], {
-        xvfb: false
         detached: true
         stdio: ["ignore", "ignore", "ignore"]
       })

test/utils_spec.coffee

@@ -1,4 +1,5 @@
 fs        = require("fs-extra")
+os        = require("os")
 mockSpawn = require("mock-spawn")
 
 fs = Promise.promisifyAll(fs)
@@ -25,17 +26,30 @@ describe "utils", ->
       utils.spawn("--foo", {foo: "bar"}).then =>
         expect(@spawn).to.be.calledWithMatch("/path/to/cypress", ["--foo"], {foo: "bar"})
 
+    it "does not call into startXvfb when its not needed", ->
+      @sandbox.spy(utils, "startXvfb")
+      @sandbox.stub(utils, "needsXfvb").returns(false)
+
+      utils.spawn("--foo")
+      .then ->
+        expect(utils.startXvfb).not.to.be.called
+
     it "starts utils.xvfb", ->
-      utils.spawn("--foo", {xvfb: true}).then =>
+      @sandbox.stub(utils, "needsXfvb").returns(true)
+
+      utils.spawn("--foo")
+      .then =>
         expect(@startAsync).to.be.calledOnce
 
     it "stops utils.xvfb when spawn closes", (done) ->
+      @sandbox.stub(utils, "needsXfvb").returns(true)
+
       spawn.setDefault (cb) =>
         cb(0)
         expect(@stopAsync).to.be.calledOnce
         done()
 
-      utils.spawn("--foo", {xvfb: true})
+      utils.spawn("--foo")
 
     it "exits with spawned exit code", (done) ->
       spawn.setDefault (cb) =>
@@ -53,7 +67,7 @@ describe "utils", ->
         unref: unref
       })
 
-      utils.spawn(null, {detached: true, xvfb: false}).then ->
+      utils.spawn(null, {detached: true}).then ->
         expect(unref).to.be.calledOnce
 
     it "does not unref by default", ->
@@ -64,9 +78,30 @@ describe "utils", ->
         unref: unref
       })
 
-      utils.spawn(null, {xvfb: false}).then ->
+      utils.spawn(null).then ->
         expect(unref).not.to.be.called
 
+  context ".needsXfvb", ->
+    afterEach ->
+      delete process.env.DISPLAY
+
+    it "does not need xvfb on osx", ->
+      @sandbox.stub(os, "platform").returns("darwin")
+
+      expect(utils.needsXfvb()).to.be.false
+
+    it "does not need xvfb on linux when DISPLAY is set", ->
+      @sandbox.stub(os, "platform").returns("linux")
+
+      process.env.DISPLAY = ":99"
+
+      expect(utils.needsXfvb()).to.be.false
+
+    it "does need xvfb on linux when no DISPLAY is set", ->
+      @sandbox.stub(os, "platform").returns("linux")
+
+      expect(utils.needsXfvb()).to.be.true
+
   context "#getCypressPath", ->
     beforeEach ->
       @log = @sandbox.spy(console, "log")