The favorite lookup should be by 'usage' (kinda interface) and by model
name ('components()' method).  The lookup by component name should
normally not be used as it reduces the flexibility.  Using a different
method for this lookup discourage its usage.  Also, the lookup by
component name completely ignores the current collection, which is bad
or not bad depending of what you want to achieve.

when inheriting from multiple components, we might inadvertly override a
value with None

Used for instance by the 'ecommerce' components

The mapping methods are now built by the component initialization when
the "aggregated" class is built.

And remove automatic naming from class name, not explicit enough,
especially when we have to inherit from one.

We could take the total opposite and only use class names components:

class MyComponent(Component):
    ...

class MyComponentExtended(Component):
    _inherit = 'MyComponent'

But it would be less close to the odoo's API.

============================================================================================================= test session starts =============================================================================================================
platform linux2 -- Python 2.7.9, pytest-3.0.7, py-1.4.33, pluggy-0.4.0
run-last-failure: run all (no recorded failures)
rootdir: /opt/odoo, inifile:
plugins: cov-2.5.1, odoo-0.2.2
collected 25 items
odoo/external-src/connector/component/tests/test_build_component.py .........
odoo/external-src/connector/component/tests/test_component.py ........
odoo/external-src/connector/component/tests/test_lookup.py ......
odoo/external-src/connector/component/tests/test_work_on.py ..
---------- coverage: platform linux2, python 2.7.9-final-0 -----------
Name                                                                  Stmts   Miss  Cover
-----------------------------------------------------------------------------------------
odoo/external-src/connector/component/__init__.py                         4      0   100%
odoo/external-src/connector/component/__manifest__.py                     1      1     0%
odoo/external-src/connector/component/base_components.py                  3      0   100%
odoo/external-src/connector/component/builder.py                         18      0   100%
odoo/external-src/connector/component/core.py                           155      6    96%
odoo/external-src/connector/component/exception.py                        3      0   100%
odoo/external-src/connector/component/models/__init__.py                  1      0   100%
odoo/external-src/connector/component/models/collection.py                8      0   100%
odoo/external-src/connector/component/tests/__init__.py                   4      0   100%
odoo/external-src/connector/component/tests/common.py                    26      2    92%
odoo/external-src/connector/component/tests/test_build_component.py     102      0   100%
odoo/external-src/connector/component/tests/test_component.py            56      0   100%
odoo/external-src/connector/component/tests/test_lookup.py               84      0   100%
odoo/external-src/connector/component/tests/test_work_on.py              26      0   100%
-----------------------------------------------------------------------------------------
TOTAL                                                                   491      9    98%
========================================================================================================== 25 passed in 0.76 seconds ==========================================================================================================

the 'components' method had 2 different return types depending of the
'multi' argument.

Now we have 'component' or 'many_components' that return a Component
instance or a list of Component instances.

Proposing a new API based on components for the events

Because they can have different addons

* Move the methods to get components from the components to the
WorkContext, it should really be its responsibilities to get them.
There are shorcuts on the components though.
My first implementation was like that, then I moved the lookup methods
on the components thinking that it would allow to customize them. But if
we did that, we would have a different behavior from component to
component which is bad, so if one really wanted to do that, better have
to work with a different subclass of WorkContext, which would have its
own behavior, consistently throughout all the work session.

* Allow to switch the collection using work_on(), not only the
  model_name

Tests using odoo transactions must run post install, because during the
install the registry is not ready, so the components aren't neither.

For consistency, this is where components should go (as for models,
views, ...)

Checking that the odoo registry is ready is not working:
in tests, the events are not working because they are run
just before the odoo registry is set to ready.

(might be empty for EventWorkContext)

It allows to open/close objects on start/end of a synchro / work
session. The base method does none of that, but this is a really common
use case. Example: at the beginning of the work session, I open a
webservice client that is available in our WorkContext for the duration
of our work. At the end, I close the client to end the connection.

…ule is loaded with test-enable=True, the components of this module are not registerd by the call to the method _register_hook of the component.builder. Indeed the state of the module is still *to install*. This change allows to call the method *load_components* on the component.builder for a specific module by taking care to not reload the components of a module already loaded.