374 / 478
lists/tests/test_views.py (ch19l017).
@patch
(
'lists.views.render'
)
def
test_renders_home_template_with_form_if_form_invalid
(
self
,
mock_render
,
mockNewListForm
):
mock_form
=
mockNewListForm
.
return_value
mock_form
.
is_valid
.
return_value
=
False
response
=
new_list2
(
self
.
request
)
self
.
assertEqual
(
response
,
mock_render
.
return_value
)
mock_render
.
assert_called_once_with
(
self
.
request
,
'home.html'
, {
'form'
:
mock_form
}
)
That gives us:
AssertionError: <django.http.response.HttpResponseRedirect object at
0x7f8d3f338a50> != <MagicMock name='render()' id='140244627467408'>
When using assert methods on mocks, like
assert_called_
once_with
, it’s doubly important to make sure you run the test and
see it fail. It’s all too easy to make a typo in your assert function name
and end up calling a mock method that does nothing (mine was to
write
asssert_called_once_with
with three essses, try it!)
We make a deliberate mistake, just to make sure our tests are comprehensive:
lists/views.py (ch19l018).
def
new_list2
(
request
):
form
=
NewListForm
(
data
=
request
.
POST
)
list_
=
form
.
save
(
owner
=
request
.
user
)
if
form
.
is_valid
():
return
redirect
(
list_
)
return
render
(
request
,
'home.html'
, {
'form'
:
form
})
That passes but it shouldn’t! One more test then:
lists/tests/test_views.py (ch19l019).
def
test_does_not_save_if_form_invalid
(
self
,
mockNewListForm
):
mock_form
=
mockNewListForm
.
return_value
mock_form
.
is_valid
.
return_value
=
False
new_list2
(
self
.
request
)
self
.
assertFalse
(
mock_form
.
save
.
called
)
346
|
Chapter 19: Test Isolation, and “Listening to Your Tests”