And write a *real* smoke test.

Reported by @martymcmahon in #1354.

Also added tests for changing the line and order status. Unfortunately,
I had to introduce test-global status pipelines instead of using
overridden_settings(). Even though I both applied it in setUp() and the
individual tests, the forms were rendered with no statuses available.

Fixes #1354.

When ordering a basket of free products, or with vouchers giving 100%
discount, we should not collect payment details.

To achieve this, I've added a check to the CheckoutSessionMixin which
calculates the order total and decides whether payment is necessary.

The modified test failed because the OrderCalculator called by
check_payment_is_necessary accessed other properties on the shipping
method. We now just mock a valid shipping method, which still achieves
the aim of ensuring there's only one.

Oscar already has child products to model tightly coupled products, and
"recommended products" to model products that are related (which we
expect to mostly be used for upselling). Product.related_products was a
third option that sat somewhere inbetween, and which I think will often
not be needed, has a mediocre interface in the dashboard and beyond that
no special treatment in the codebase. Furthermore, I see it being
confusing when trying to model a catalogue, and it's easily added back
if necessary.

This is quite a large change. It:

- Alters the add-to-basket URL to have the "base" product's PK in it
- Changes the constructor of the AddToBasket form to not require
  purchase_info (even though I only just introduced it!)
- Renames the product_id field to variant_id and only uses it for group
  products

These changes are motivated by the variant workflow. Before this change,
you effectively had different forms being used for rending and
validation as the product being passed to the form constructor was the
group product when rendering but the variant when validating. This just
about worked but was not nice.

The purchase_info param is removed as we can only calculate the
purchase_info once the variant product has been validated. Hence we
again violate Demeter and make a deep call to the purchase info
calculation within the basket form. Might revisit this again.

This change also simplifies the basket view logic and allows a form to
be removed.

Conceptually, save() is the wrong place for model validation. ModelForms
call clean() before saving, so the results should be the same as long as
they are used.

Fixes #1297.

This means we don't need to do the law-of-demeter-violating call to
fetch the purchase info for a product (line 79 of forms.py). HOWEVER,
I'm starting to have second thoughts about this - I've discovered that
the adding to basket process is quite confusing for variants and I
intend to refactor.

This commit also adds some useful tests though so it's a valid stepping
stone to a better place.

This change includes some tidying and organisational changes. There's
also a new test for adding order notes.

The new version has been extended to allow the success URLs and messages
to be easily customised.

We also now redirect staff members to the dashboard when they first
login.

Oddly enough, the warnings were only thrown under Python 2.6. Should
investigate!

A bit OCD, but I noticed that the checkout forms were an exception in
using a hyphen so I've cleaned up all IDs to use underscores.

Before this change, it was conflating WebTest functionality with the
Django test client. This change removes the Django test client
functionality (namely, the login function which was being automatically
called).

A shed-load of tests are adjusted to work with this change.

This almost completes the work for #826 - only a couple more references
to the Django client are left in the test codebase.

We no longer use Django's test client.

- Comment the session manager better.
- Clean up the functional checkout tests.

Issue #888 mentioned that this is recommended in Google's SEO guide.

It is now replaced with a checkout pre-condition that applies to every
checkout view. If someone's basket becomes invalid while they are in
checkout, then they will be redirected back to the basket page.

This change introduces a new framework for enforcing checkout
pre-conditions. Each view class can define a class attribute
'pre_conditions' which lists method names to run before the class
itself.

Of course, decorators are more conventional for this kind of thing but
they are harder to override and customise.

underscore as separator.
Changed setup of functional test in dashboard/communication to be passed
with code populated from name.

Now that Oscar's simple search has been removed, ProductListView does
nothing but show all products. It's been incorporated into
ProductCategoryView.

ProductListView used to give out an invalid summary; this is now fixed.

ProductCategoryView used to pass 'categories' in the template context,
but it wasn't used.

Using "partner" is easily confused with passing an actual partner
instance.

Previously, the 'key' kwarg was not respected and all products would get
added to the first wishlist.

Thanks to @DanielChu for reporting, and supplying a fix.
Fixes #1216

On my local machine, django-dynamic-fixture created product classes
where the slug and primary key were identical and the tests passed
although the check was wrong. Luckily, Murphy's Law works in our favour
on Travis CI, and that failed and spotted it.

This commit fixes the assumption that the redirect view expects the slug
(which it doesn't since the last commit), and ensures that the generated
product classes are non-numeric.

During the registration and in dashboard, the new password is required
to have min 6 characters and not be in common passwords. Those rules are
not enforced when changing password in the account section or resetting
password.

Extract password validators into core validators as they are used by
multiple apps. `password_validators` now contains all validators applied
to passwords: DRY principle.

Changed auth tests to have a proper password for password reset.

This gives more readable URLs.

Fixes #1186

This should always be used instead of Django's silent version.

Previously, the test suite ran with a custom user model for Django >=
1.5, but it didn't subclass Oscar's AbstractUser.  This commit adjusts
the custom user model to subclass Oscar's so we can test functionality
within the custom user class.

This does require a change to the way tests authenticate as we don't
actually use the username field.

This reverts fa1f8403 which moved them from models.py to __init__.py.
As reported by @mvantellingen, importing receivers from __init__.py
breaks the way models are normally overridden as it causes the core
models.py to get imported before the custom one.

We need to move back to the old system and will need to advise that the
debug toolbar needs to be set-up explicitly to avoid circular import
issues with models.

Fixes #1159
Original issue #1125

We add a new form to the profile section that requires the customer to
confirm their password, but which then deletes their user.

After creating a product, the flash message has links to
(a) view on site
(b) edit again.

ClientTestCase is deprecated.

Fixes #826
Fixes #1007

Analogous to the settings for the basket cookie, the cookie that stores
the recently viewed products is now configurable.

Fixes #1064