Ivor O’Connor

May 4, 2009

JavaScript Code Coverage On Ubuntu

Filed under: Code Coverage, Firefox, howto, Linux, tutorial, ubuntu — Tags: , — ioconnor @ 10:24 am

I’ve been playing with JavaScript looking for QA tools, getting JavaScript Lint in vim on Ubuntu, etc.. Now I’ve got code coverage analysis going for it. Follow these instructions to install JavaScript Code Coverage on Ubuntu:

  1. Download from and unpack.
  2. Change directory to where it was unpacked:

    cd jscoverage-0.4/
  3. Configure the environment for Ubuntu:

  4. Compile the program:

  5. Copy jscoverage-server to your personal bin:

    cp jscoverage-server /my/bin
  6. The jscoverage documentation does not mention it but you must start jscoverage-server from the directory where it is to be serving the javascript from. So to run their examples move to the directory where their example code is:

    cd jscoverage-0.4/doc/example/
  7. Now start up the coverage server from the same directory the javascript is located:

    jscoverage-server –verbose
  8. Open up a browser where index.html is the starting point of the code you are going to test:

  9. Execute the code a bit and then move to the store tab and press the store button.
  10. Open up another browser to view the results:

    firefox jscoverage-report/jscoverage.html
  11. Possibly open another browser, like opera, and test with it. All the additional tests will be added to the report.
  12. Now if you have the directory available via the network test the code with IE.

At this point it’s a simple matter of writing the javascript as a separate library.
Once in a separate library each function can be called separately.
Unit tests can then be written attempting to maximize code coverage and results can be verified.
Once this is done then the user interfaces can be tested.

There are some caveats listed in the manual. They all seem quite acceptable.

  1. JSCoverage adds instrumentation to JavaScript code, which will slow down execution speed. Expect instrumented code to take at least twice as much time to run.
  2. JSCoverage currently instruments only .js files; it does not instrument code in script elements in HTML files.
  3. HTML files must use relative URLs to reference scripts. If you use an absolute URL, your page will reference the original uninstrumented script rather than the instrumented one, and no code coverage data will be collected.
  4. JSCoverage instruments physical lines of code rather than logical JavaScript statements; it works bests with code that has exactly one statement per line. If you put multiple statements on a line, or split a line across two or more statements, you may get strange results.
  5. JSCoverage uses frames. Some web pages that use frames may not function properly when run under JSCoverage, especially those which try to access the top-level frame (window.top, target=”_top”, etc.).

I don’t see any way of incorporating the results into vim.
It would be nice if that were possible though.
I think the best that can be done would simply be to start a page that would call the various functions with assert statements.
Perhaps via a bash script.
Maybe I’ll learn more when I look into the jsunit tools.
As it now stands all of the error paths are questionable.
Still it’s better than no code coverage.

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