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0004_item_list.py:
- Add field list to item
Deleting migrations is dangerous. If you delete a migration that’s
already been applied to a database somewhere, Django will be con‐
fused about what state it’s in, and how to apply future migrations.
You should only do it when you’re sure the migration hasn’t been
used. A good rule of thumb is that you should never delete a migra‐
tion that’s been committed to your VCS.
Adjusting the Rest of the World to Our New Models
Back in our tests, now what happens?
$
python3 manage.py test lists
[...]
ERROR: test_displays_all_items (lists.tests.ListViewTest)
django.db.utils.IntegrityError: NOT NULL constraint failed: lists_item.list_id
[...]
ERROR: test_redirects_after_POST (lists.tests.NewListTest)
django.db.utils.IntegrityError: NOT NULL constraint failed: lists_item.list_id
[...]
ERROR: test_saving_a_POST_request (lists.tests.NewListTest)
django.db.utils.IntegrityError: NOT NULL constraint failed: lists_item.list_id
Ran 7 tests in 0.021s
FAILED (errors=3)
Oh dear!
There is some good news. Although it’s hard to see, our model tests are passing. But
three of our view tests are failing nastily.
The reason is because of the new relationship we’ve introduced between Items and Lists,
which requires each list to have a parent item, which our old tests weren’t prepared for.
Still, this is exactly why we have tests. Let’s get them working again. The easiest is the
ListViewTest
; we just create a parent list for our two test items:
lists/tests.py (ch06l031).
class
ListViewTest
(
TestCase
):
def
test_displays_all_items
(
self
):
list_
=
List
.
objects
.
create
()
Item
.
objects
.
create
(
text
=
'itemey 1'
,
list
=
list_
)
Item
.
objects
.
create
(
text
=
'itemey 2'
,
list
=
list_
)
That gets us down to two failing tests, both on tests that try to POST to our
new_list
view. Decoding the tracebacks using our usual technique, working back from error, to
line of test code, to the line of our own code that caused the failure, we identify:
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Chapter 6: Getting to the Minimum Viable Site