CONFspirator in your unit tests¶
You often need ways to override config when running tests, so CONFspirator provides some powerful ways to do that even for the most complicated of nested configs.
Setting test defaults¶
The first smart thing to do is set the test_default
value on
a given config field for something you want to be a global test
default value. This is useful for values you rarely need to
change, and this means you can put your test defaults in the
same places you define you config and put your actual defaults.
An example of this might be:
config_group.register_child_config(
fields.StrConfig(
"my_string_config",
help_text="Some useful help text.",
required=True,
default="stuff",
test_default="test_specific_stuff",
)
)
To ensure CONFspirator uses the test_default
you will need to put it
into test_mode
when running the load config functions:
CONF = confspirator.load_file(
config_group, "/etc/my_app/conf.yaml", test_mode=True)
That does mean you will need some way to decide when loading config
if your application is running in test_mode
. This will vary depending
on your framework, or unit testing tools, but as an example, in Django
you could do it as follows:
test_mode = False
if "test" in sys.argv:
test_mode = True
CONF = confspirator.load_file(
config_group, "/etc/my_app/conf.yaml", test_mode=test_mode)
Overriding config for test cases¶
Often in unit or functional testing you need ways to override config for the duration of a test, a whole set of tests, or even in different phases of a test.
As such CONFspirator provides an all powerful modify_conf
function
that alows you to selectively alter your config entity for the needed
scope.
Note
modify_conf
assumes your test case classes inherit from
unittest.TestCase
. If they do not, then this will not work.
A simple example:
import confspirator
from my_app.config import CONF
@confspirator.modify_conf(
CONF,
{
"my_app.top_level_config": [
{"operation": "override", "value": "a new value"}
],
}
)
class BasicTests(TestCase):
def test_top_level_config(self):
self.assertEqual(CONF.top_level_config, "a new value")
It can also be used to decorate a single test function:
import confspirator
from my_app.config import CONF
class BasicTests(TestCase):
@confspirator.modify_conf(
CONF,
{
"my_app.top_level_config": [
{"operation": "override", "value": "a new value"}
],
}
)
def test_top_level_config(self):
self.assertEqual(CONF.top_level_config, "a new value")
Or even a section when using the with
keyword:
import confspirator
from my_app.config import CONF
class BasicTests(TestCase):
def test_top_level_config(self):
with confspirator.modify_conf(
CONF,
{
"my_app.top_level_config": [
{"operation": "override", "value": "a new value"}
],
},
):
self.assertEqual(CONF.top_level_config, "a new value")
parameters for modify_conf¶
modify_conf
takes two argument which can be used positionally, or
as keywords.
conf¶
This should be the loaded config entity and will be either an
instance of GroupNamespace
or in advanced cases
LazyLoadedGroupNamespace
.
operations¶
This is a dictionary of config values as dot separated paths to a list of operations.
It is possible to alter multiple config values at the same time, and run multiple operations on each. Operations will run in the order supplied and can be chained together (e.g. add a value to the start and end of a list).
Here is what a more complex example may look like:
operations={
"my_app.api_settings.item_list_option": [
{"operation": "remove", "value": "option1"},
{"operation": "append", "value": "option15"},
],
"my_app.api_settings.boolean_flag_option": [
{"operation": "override", "value": False},
],
}
Available operations per config type¶
- value:
override
- list:
override
preprend
append
remove
- dict:
override
update
delete
overlay
- GroupNamespace:
override
overlay
Overlay is essential a dict merge, where any keys present in the overlaying dictionay will be inserted or will override the ones in the target.