Jerome says this is partially done.

there are some unit tests in /webservice/simpletest/testwebservice.php. The test instructions are in the phpdoc.

Currently, the existing web service unit tests are for:

• moodle_group_get_groups (compare the groups total)
• moodle_user_get_users_by_id (compare the users total)
• moodle_enrol_get_enrolled_users (compare the enrolled users total for every courses)
• moodle_course_create_courses (compare values of two created courses)
• moodle_user_create_users (compare values of two created users)
• mooodle_course_get_courses (compare the courses total and all the courses values)

The missing core web service unit tests are:

all done!

Added:

• support for PHP soap options in our client (example: SOAP synchronous mode)
• fix moodle_user_get_users_by_id unit test that compared with deleted users
• add moodle_user_delete_users unit test

Added moodle_user_update_users() (compare two temporary users values, all of the possible values accepted by web services).
Unit test for users and courses are in CVS.

maybe someone should review this unit test file?

This unit test file can be run on production test, it doesn't do anything till you edit the file.

These unit tests are calling the real web service functions (purpose of the testing). So some manual setup is needed (you need to create a web service token and to edit it in the unit test code) + some data could potentially be written into the database (you need to manually activate the function test).

added moodle_role_assign and moodle_role_unassign.
The only externallib.php file left not 100% unit tested is group now...

added moodle_get_course_groups and moodle_get_group_members

Ok all done, all passed (SOAP and XMLRPC).

Even though, there are still lots to be improved. For example we could be extending the unit test class like in backup unit tests (I just discover that, but the fact that we test web service call could not allow it anyway).

I did some performance testing too, to run all of them:
xmlrpc: 70s
soap: 32s