Code coverage reporting (via xdebug)

Instruction:
0) enable xdebug php extension.
1) enable php_coverage module from php_coverage.zip. It's without comments, sorry.
2) edit this lines in php_coverage.module:

define('PHP_CODE_COVERAGE_SETTINGS_FILE', '/tmp/coverage_settings');
define('PHP_CODE_COVERAGE_DATA_FILE', '/tmp/coverage_data');

There should be absolute paths.
This files are created automatically and they don't need after running tests.
This files hold settings and a coverage data between subrequests.

3) edit setings in admin/settings/testing. Set 'Include paths' and 'Exclude paths' as you wish. One path for one line, relative to the Drupal root.
4) apply the patch php_coverage.patch
5) go to admin/build/testing (Testing) and run one test (Block functionality eg.)
6) go to admin/build/testing/coverage (Coverage report).

Here you can see a list of covered files (coverage_report.png).

If you click a file you'll see a code coverage report for the file (coverage_file.png).

Advantages:
1) this code coverage handles subrequests' coverages like $this->drupalPost();
2) a highlight php code capability
3) this is not depended on external stuff

There are fullsize screenshots so you can see it.

• p1_settings.png - settings for the code coverage.
• p2_test_list.png - "testing" menu with 2 tabs
• p3_report.png - a list of covered files after "Block functionality" tests.
• p4_file.png - coverage details for "modules/block/block.module" file.

It seems I should change "status".

Thanks to all for the interest and advice.

I've merged the simpletest module and the previous stuff.
Let's look how it works now.

Now if you have XDebug enabled then there are 2 tabs: "Test lists" and "Coverage report".
You can now make XDebug code coverage setup in admin/settings/testing.
Added comments, some UI tuning.
Updated screenshots in http://drupal.org/node/260032#comment-849004.

By default the code coverage disabled.

The "Instruction" from http://drupal.org/node/260032#comment-848868 is almost needless.