admin/cli/check_database_schema.php does not check indexes

Test 1

1. Create a fresh Moodle site.
2. Run php admin/cli/check_database_schema.php
3. Confirm it returns "Database structure is ok".
4. Visit the database using your favourite DB editor.
5. Edit the "mdl_messages" table and delete the indexes "conversationid, timecreated" and "conversationid".
6. Run php admin/cli/check_database_schema.php
7. Confirm you get the following -

   -------------------------------------------------------------------------------

   messages

   * Missing index 'conversationid' (not unique (conversationid)).

   CREATE INDEX mdl_mess_con_ix ON mdl_messages (conversationid);

   * Missing index 'conversationid_timecreated' (not unique (conversationid, timecreated)).

   CREATE INDEX mdl_mess_contim_ix ON mdl_messages (conversationid, timecreated);

   -------------------------------------------------------------------------------

Test 2

1. Create a fresh Moodle site.
2. Visit the database using your favourite DB editor.
3. Edit the "mdl_messages" table and delete the indexes "conversationid, timecreated" and "conversationid".
4. Create another database called anything you want.
5. Visit 'Site administration' > 'Development' > 'Experimental' > 'Database migration'.
6. Enter in the details for the new database you created.
7. Click 'Transfer data'.
8. Confirm it transferred correctly.

Test 3 (master only)

1. Create a fresh Moodle site.
2. Visit 'Site administration' > 'Development' > 'XMLDB editor'.
3. Click on 'Check indexes'.
4. Click 'Yes'.
5. Confirm it says "No missing or extra indexes have been found, your DB doesn't need further actions.".
6. Visit the database using your favourite DB editor.
7. Edit the "mdl_messages" table and add a new index on the "customdata" field.
8. Visit 'Site administration' > 'Development' > 'XMLDB editor'.
9. Click on 'Check indexes'.
10. Click on 'Yes'.
11. Confirm it says that you have 1 additional one.

Test 4 (master only)

1. Create a fresh Moodle site.
2. Run php admin/cli/check_database_schema.php
3. Confirm it returns "Database structure is ok".
4. Visit the database using your favourite DB editor.
5. Edit the "mdl_messages" table and add a new index on the "customdata" field.
6. Run php admin/cli/check_database_schema.php
7. Confirm you get the following -

   -------------------------------------------------------------------------------

   messages

   * Unexpected index 'mdl_messages_customdata'.

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