Use scope and closures to make all gadget module alike.

Add a test about checking quantity unit behavior on movement. Quantity unit set to movement must not be changed by changing default quantity unit on resource. This test will fail as expected.

add new assert to support range of values expected. The position is calculated on planning box and is returning small difference on value in each testnode result. With this, the test was changed to support this range.

TIDStorage monkey-patches ZEO so it imported it before 'custom_zodb' is loaded.
This commit fix 'custom_zodb' to reset ZEO triggers.

This revert a wrong change in commit 8995b645

Move active context creation, active callable creation, packet length test
out of loop.

That change makes no sense latency-wise, iteration will anyway happen
inside "list()". Also, it potentially degrades memory usage.

use key press instead of click on button save to avoid permission denied failure with selenium and firefox

Reduce differences between similar tests.
Remove bit-rot comments.
Simplify code (avoid redundant lookups, ...).
Also, make easier to subclass and use for a different category tree.

Still, don't fail depending on day of week.

Also, update exception raising style.

Those are single-valued, so just check consistency internally and return
a single value.
Changelog and some cleanups by Vincent Pelletier <vincent@nexedi.com>.

It is known to cause table locks when no value is provided for such
column. We now always generate uids in ERP5, so this setting is useless.

-user with correct permissions should be able to set start or stop date. Add proxy role manager in scripts.

See testTradeModelLine for new use of taxes/discounts.