==== How to look at the test coverage for an extension - eg /ext/dom ====

  * Make sure that you have LTP installed, for Ubuntu:
      * sudo apt-get install ltp 
      * sudo apt-get install lcov

=== Checkout the PHP53 code and build it ===
  * Checkout or download PHP53 into directory of your choice (in my case /home/zoe/BUILDS/php53_dev)
  * cd /home/zoe/BUILDS/php53_dev
  * ./buildconf
  * ./configure --enable-gcov
  * make

=== Check the coverage of a single extension ===
  * make a new directory somewhere (eg /home/zoe/TESTS/coverage) and cd to it
  * create a script (run_coverage) file to run the tests, eg
<code>
export TEST_PHP_EXECUTABLE=/home/zoe/BUILDS/php53_dev/sapi/cli/php
$TEST_PHP_EXECUTABLE /home/zoe/BUILDS/php53_dev/run-tests.php /home/zoe/BUILDS/php53_dev/ext/dom
</code>
   * ./run_coverage. This runs all the tests found under php53_dev/ext/dom
   * lcov --directory /home/zoe/BUILDS/php53_dev/ext/dom -c -o dom.info
   * genhtml dom.info -o dom_coverage. This will make a directory called dom_coverage with html coverage files in it.
   * View the coverage files :-)

==== How would I look at the coverage of a subset of the tests? ====
For example - suppose I wanted to take all the tests which are there because of bug reports and just look at what the base test cases cover.
  * cd /home/zoe/BUILDS/php53_dev/ext/dom
  * '' find tests -name "bug*.phpt" | xargs -i mv {} {}.bak ''   ( Copies all the tests to test.phpt.bak ) 
  * make clean; make
  * cd /home/zoe/TESTS/coverage; ./runcov.sh run
  * run lcov and genhtml as above

Just for interest, the code coverage of the dom extension without the bug tests is 2101 of 4708 lines (44.6%).

Don't forget to copy the bug tests back afterwards:
  * '' find tests -name "bug*.phpt.bak" | sed 's/.bak/ /' | xargs -i mv {}.bak {} ''
  * NB: no space between the two slashes after .bak