Use the proper assertion methods of the mocks.

Change-Id: I7b02f3b52012976a3ed0b8d5fc445653c0546547

- Added a MapFunctorTask and ReduceFunctorTask to mimic the python
  builtin functions map and reduce, respectively

Change-Id: I29cd1249e1671aedfd2d25460d746b8d2154df2b

Instead of using always using a set/dict which do not retain
use a ordered set and a ordered dict for requires, optional,
and provides and rebind mappings types so that the ordering
of these containers is maintained later when they are used.

These ordering can be useful depending on the atom type (such
as in a map and reduce tasks).

Partial-Bug: 1357117

Change-Id: I365d11bbba4aa221bc36ca15441acecf199b4d56

Optional arguments that are not explicitly required are being ignored
when arguments are being mapped based on inference from atoms' execute
method signatures.  This patch adds support for mapping optional
arguments in addition to required arguments.

Change-Id: I440c02dcd901a563df512e33754b13e3c05d4155

To make it easy to add new type errors and to make the existing
ones have a common string pattern adjust the current type errors
to contain at least the following string format: '%s' (%s) where
these two places will be filled in with the object of the wrong
type and the type of that object. This information is useful when
analyzing the exception (by the user) to know exactly what they
passed in and what type it was.

This convention is not maintained where it would interpolate large
text blobs (such as in binary encoding/decoding and json decoding).

Change-Id: Id84b0e7ce684a543cc407b15016e77804e6f03ed

Instead of having code that is some what like the notifier
code we already have, but is duplicated and is slightly different
in the task class just move the code that was in the task class (and
doing similar actions) to instead now use a notifier that is directly
contained in the task base class for internal task triggering of
internal task events.

Breaking change: alters the capabilities of the task to process
notifications itself, most actions now must go through the task
notifier property and instead use that (update_progress still exists
as a common utility method, since it's likely the most common type
of notification that will be used).

Removes the following methods from task base class (as they are
no longer needed with a notifier attribute):

- trigger (replaced with notifier.notify)
- autobind (removed, not replaced, can be created by the user
            of taskflow in a simple manner, without requiring
            functionality in taskflow)
- bind (replaced with notifier.register)
- unbind (replaced with notifier.unregister)
- listeners_iter (replaced with notifier.listeners_iter)

Due to this change we can now also correctly proxy back events from
remote tasks to the engine for correct proxying back to the original
task.

Fixes bug 1370766

Change-Id: Ic9dfef516d72e6e32e71dda30a1cb3522c9e0be6

When a engine needs to copy a task and possibly
adjust its listeners to execute it elsewhere it
needs to be able to clone that object and have
the clone retain different properties than the
initial object; so in order to support this at
a top-level we require a new copy() method which
a task can override (or it can just use the default
implementation if it chooses to).

Part of blueprint process-executor

Change-Id: Ib29a0afdc01973eb94d41af18a9b04601cd2f152

Unifies the bind, unbind, autobind parameters.

Also to make it easier to introspect what are a tasks associated
callbacks and events are provide a listeners_iter() method that
can be used to introspect the registered (event, callbacks) pairs that
are registered with a task.

Also adds more useful docstrings to the various callback associated
binding, unbinding functions to make it more understandable how they
are used and what they are provided.

Also makes the currently only default provided event 'update_progress'
a constant that can be referenced from the task module, which allows others
to easily find it and use it.

Change-Id: I14181a150b74fbd97f6ea976723f37c0ba4cec36

Since asserts can be silenced using -0 and/or compiled out
we want to be more strict here and raise value errors when the
expected callable objects/functions are not actually callable.

Change-Id: Ib14e2e7329dbfcce50660f144ad4780d99f36854

The oslotest library has a nice openstack testing integrated
base class that can ensure we setup our base test case using
the right logging fixtures, test timeouts, and output fixtures
that better operate in the openstack ecosystem.

This will also allow us to remove some of the functionality
that we currently have in our base test case and replace it with
the equivalent (or better) functionality that oslotest now
provides.

Part of blueprint use-oslo-test

Change-Id: I1602d5180ec8649a1899185972750ddddf65990f