COMMANDS (perhaps keep these notes in $command definition?)
------------
pm-download: GOOD.
pm-updatecode: GOOD.
pm-update
pm-releasenotes
pm-releases
pm-enable: GOOD. testEnDisUnList().
pm-disable: GOOD. testEnDisUnList().
pm-uninstall: GOOD. testEnDisUnList().
pm-list: GOOD. testEnDisUnList().
pm-info:
pm-refresh
version-control: FAIR. See updatecode. To be deprecated all git workflow after git.drupal.org?
package-hander:

sql-cli:
sql-connect:
sql-query:
sql-dump: FAIR. Implicitly tested by siteUpgradeTest.
sql-sync: FAIR. Implicitly tested by siteUpgradeTest.
sql-drop:


updatedb: GOOD. Implicitly tested siteUpgradeTest.
archive-dump: GOOD
archive-restore: 
help
version: Good. Implicit by testStandaloneScript()
self-update
php-eval: GOOD. Implicitly tested by many tests (e.g. siteUpgradeTest).
php-script: GOOD.
drupal-directory: GOOD
core-cli: FAIR
cache-clear
core-cron
core-status: FAIR: Implicit test by contextTest.
docs
image
core-rsync
search-*
site-install: FAIR. Implicit test by setUpDrupal().
site-upgrade: GOOD.
test-*
topic
variable-*: GOOD.
watchdog-*

user-*: GOOD.

field-*: GOOD.

INCLUDES
------------
backend: GOOD
batch: FAIR. Implicit by siteUpgradeTest.
command: FAIR
context: FAIR
drush: NONE.
environment
sitealias. FAIR. Explicit test for alias lists. Single aliases implicitly tested by contextTest.
dbtng: Good. Implicit by variable-*.
drupal
exec: GOOD: Implicitly tested all over.
filesystem
output


ROOT
-------------
drush
drush.php
drush.bat