Installing/using Selenium for Nightwatch.js in C9.io

I'm trying to use Nightwatch.js to do automated unit and end-to-end testing. Nightwatch.js depends on Selenium.

I have determined how to install it ( see "Steps to install Selenium" below ), and can get the Selenium server started (via bin/ java -jar selenium-server-standalone-2.48.2.jar).
However, when I try to actually run a basic nightwatch test, I get errors due to browser, url, and port configuration problems (errors below).
Any chance someone can provide some hints on how I should configure the nightwatch.json file to work with Selenium installed into C9?

Steps to install Selenium

mkdir bin
cd bin
wget "http://selenium-release.storage.googleapis.com/2.48/selenium-server-standalone-2.48.2.jar"
unzip selenium-server-standalone-2.48.2.jar
cd ..

LOG

03:26:27.875 INFO - Executing: [new session: Capabilities [{platform=ANY, acceptSslCerts=true, javascriptEnabled=true, browserName=firefox, name=Basic}]])
03:26:27.893 INFO - Creating a new session for Capabilities [{platform=ANY, acceptSslCerts=true, javascriptEnabled=true, browserName=firefox, name=Basic}]
org.openqa.selenium.firefox.NotConnectedException: Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms. Firefox console output:

(process:3585): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
Error: no display specified

        at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:122)
        at org.openqa.selenium.firefox.FirefoxDriver.startClient(FirefoxDriver.java:271)
        at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:117)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:218)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:211)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:129)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.openqa.selenium.remote.server.FirefoxDriverProvider.callConstructor(FirefoxDriverProvider.java:91)
        at org.openqa.selenium.remote.server.FirefoxDriverProvider.newInstance(FirefoxDriverProvider.java:68)
        at org.openqa.selenium.remote.server.DefaultDriverFactory.newInstance(DefaultDriverFactory.java:60)
        at org.openqa.selenium.remote.server.DefaultSession$BrowserCreator.call(DefaultSession.java:222)
        at org.openqa.selenium.remote.server.DefaultSession$BrowserCreator.call(DefaultSession.java:1)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at org.openqa.selenium.remote.server.DefaultSession$1.run(DefaultSession.java:176)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
03:27:13.875 WARN - Exception thrown
java.util.concurrent.ExecutionException: org.openqa.selenium.WebDriverException: java.lang.reflect.InvocationTargetException
Build info: version: '2.48.2', revision: '41bccdd', time: '2015-10-09 19:59:12'
System info: host: 'metasean-learnin-nightwatch-2330511', ip: '172.17.33.167', os.name: 'Linux', os.arch: 'amd64', os.version: '4.2.0-c9', java.version: '1.7.0_85'
Driver info: driver.version: unknown
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:188)
        at org.openqa.selenium.remote.server.DefaultSession.execute(DefaultSession.java:183)
        at org.openqa.selenium.remote.server.DefaultSession.<init>(DefaultSession.java:119)
        at org.openqa.selenium.remote.server.DefaultSession.createSession(DefaultSession.java:95)
        at org.openqa.selenium.remote.server.DefaultDriverSessions.newSession(DefaultDriverSessions.java:124)
        at org.openqa.selenium.remote.server.handler.NewSession.handle(NewSession.java:58)
        at org.openqa.selenium.remote.server.handler.NewSession.handle(NewSession.java:1)
        at org.openqa.selenium.remote.server.rest.ResultConfig.handle(ResultConfig.java:111)
        at org.openqa.selenium.remote.server.JsonHttpCommandHandler.handleRequest(JsonHttpCommandHandler.java:175)
        at org.openqa.selenium.remote.server.DriverServlet.handleRequest(DriverServlet.java:202)
        at org.openqa.selenium.remote.server.DriverServlet.doPost(DriverServlet.java:164)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
        at org.openqa.selenium.remote.server.DriverServlet.service(DriverServlet.java:130)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
        at org.openqa.jetty.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
        at org.openqa.jetty.jetty.servlet.ServletHandler.dispatch(ServletHandler.java:680)
        at org.openqa.jetty.jetty.servlet.ServletHandler.handle(ServletHandler.java:571)
        at org.openqa.jetty.http.HttpContext.handle(HttpContext.java:1526)
        at org.openqa.jetty.http.HttpContext.handle(HttpContext.java:1479)
        at org.openqa.jetty.http.HttpServer.service(HttpServer.java:920)
        at org.openqa.jetty.http.HttpConnection.service(HttpConnection.java:820)
        at org.openqa.jetty.http.HttpConnection.handleNext(HttpConnection.java:986)
        at org.openqa.jetty.http.HttpConnection.handle(HttpConnection.java:837)
        at org.openqa.jetty.http.SocketListener.handleConnection(SocketListener.java:243)
        at org.openqa.jetty.util.ThreadedServer.handle(ThreadedServer.java:358)
        at org.openqa.jetty.util.ThreadPool$PoolThread.run(ThreadPool.java:537)
Caused by: org.openqa.selenium.WebDriverException: java.lang.reflect.InvocationTargetException
Build info: version: '2.48.2', revision: '41bccdd', time: '2015-10-09 19:59:12'
System info: host: 'metasean-learnin-nightwatch-2330511', ip: '172.17.33.167', os.name: 'Linux', os.arch: 'amd64', os.version: '4.2.0-c9', java.version: '1.7.0_85'
Driver info: driver.version: unknown
        at org.openqa.selenium.remote.server.FirefoxDriverProvider.callConstructor(FirefoxDriverProvider.java:101)
        at org.openqa.selenium.remote.server.FirefoxDriverProvider.newInstance(FirefoxDriverProvider.java:68)
        at org.openqa.selenium.remote.server.DefaultDriverFactory.newInstance(DefaultDriverFactory.java:60)
        at org.openqa.selenium.remote.server.DefaultSession$BrowserCreator.call(DefaultSession.java:222)
        at org.openqa.selenium.remote.server.DefaultSession$BrowserCreator.call(DefaultSession.java:1)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at org.openqa.selenium.remote.server.DefaultSession$1.run(DefaultSession.java:176)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.openqa.selenium.remote.server.FirefoxDriverProvider.callConstructor(FirefoxDriverProvider.java:91)
        ... 9 more
Caused by: org.openqa.selenium.WebDriverException: Failed to connect to binary FirefoxBinary(/usr/bin/firefox) on port 7055; process output follows: 

(process:3585): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
Error: no display specified

Build info: version: '2.48.2', revision: '41bccdd', time: '2015-10-09 19:59:12'
System info: host: 'metasean-learnin-nightwatch-2330511', ip: '172.17.33.167', os.name: 'Linux', os.arch: 'amd64', os.version: '4.2.0-c9', java.version: '1.7.0_85'
Driver info: driver.version: FirefoxDriver
        at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:134)
        at org.openqa.selenium.firefox.FirefoxDriver.startClient(FirefoxDriver.java:271)
        at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:117)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:218)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:211)
        at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:129)
        ... 14 more
Caused by: org.openqa.selenium.firefox.NotConnectedException: Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms. Firefox console output:

(process:3585): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
Error: no display specified

        at org.openqa.selenium.firefox.internal.NewProfileExtensionConnection.start(NewProfileExtensionConnection.java:122)
        ... 19 more
03:27:13.884 WARN - Exception: Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms. Firefox console output:

(process:3585): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
Error: no display specified

Solution

For others in this situation, there's some good news and some bad news.

The good news ...

At the top of the C9 workspace, click "Preview", then "Preview Running Application". This will open a new C9 tab.
Copy the portion of the new C9 tab's address bar AFTER "https://" (e.g. <project-name>-<username>.c9users.io).
In a C9 terminal, run ping <project-name>-<username>.c9users.io (replacing the <project-name>-<username>.c9users.io with your info). This returns an actual ip address.
In the nightwatch.json file, set the value of the "launch_url" to the returned ip address
You can now run nightwatch. :-)

The bad news ... - The first two tests we tried to run involved testing against browser.url then browser.end and in both cases, nightwatch's browser object appears to have been modified somewhere. We're not sure where or why or how to fix it, but without it, being able to run nightwatch isn't going to do us a lot of good. :-(