updated js tests README, --port= now optional

IPython/html/tests/casperjs/README.md

@@ -1,13 +1,23 b''
+# IPython Notebook Javascript Tests
+
 Regression tests for the web notebook. These tests depend on
 [CasperJS](http://casperjs.org/), which in turn requires
 a recent version of [PhantomJS](http://phantomjs.org/).
 
-Run the tests:
+Run the tests using:
+
+```
+iptest js
+```
+
+For finer granularity, or to specify more options, you can also run the
+following `casperjs` command
 
 ```sh
 /path/to/bin/casperjs test --includes=util.js test_cases
 ```
 
-The file `util.js` contains utility functions for tests,
-including a hardcoded path to a running notebook server
-(http://127.0.0.1:8888 by default).
+The file `util.js` contains utility functions for tests, including a path to a
+running notebook server on localhost (http://127.0.0.1) with the port number
+specified as a command line argument to the test suite. Port 8888 is used if
+`--port=` is not specified.

IPython/html/tests/casperjs/util.js

@@ -4,7 +4,9 b''
 
 // Get the URL of a notebook server on which to run tests.
 casper.getNotebookServer = function () {
-    return 'http://127.0.0.1:' + casper.cli.get("port");
+    port = casper.cli.get("port")
+    port = (typeof port === 'undefined') ? '8888' : port;
+    return 'http://127.0.0.1:' + port
 };
 
 // Create and open a new notebook.