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75 lines
3.0 KiB
ReStructuredText
75 lines
3.0 KiB
ReStructuredText
Testing Consumers
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=================
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When you want to write unit tests for your new Channels consumers, you'll
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realise that you can't use the standard Django test client to submit fake HTTP
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requests - instead, you'll need to submit fake Messages to your consumers,
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and inspect what Messages they send themselves.
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Channels comes with a ``TestCase`` subclass that sets all of this up for you,
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however, so you can easily write tests and check what your consumers are sending.
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ChannelTestCase
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---------------
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If your tests inherit from the ``channels.tests.ChannelTestCase`` base class,
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whenever you run tests your channel layer will be swapped out for a captive
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in-memory layer, meaning you don't need an exernal server running to run tests.
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Moreover, you can inject messages onto this layer and inspect ones sent to it
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to help test your consumers.
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To inject a message onto the layer, simply call ``Channel.send()`` inside
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any test method on a ``ChannelTestCase`` subclass, like so::
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from channels import Channel
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from channels.tests import ChannelTestCase
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class MyTests(ChannelTestCase):
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def test_a_thing(self):
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# This goes onto an in-memory channel, not the real backend.
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Channel("some-channel-name").send({"foo": "bar"})
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To receive a message from the layer, you can use ``self.get_next_message(channel)``,
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which handles receiving the message and converting it into a Message object for
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you (if you want, you can call ``receive_many`` on the underlying channel layer,
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but you'll get back a raw dict and channel name, which is not what consumers want).
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You can use this both to get Messages to send to consumers as their primary
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argument, as well as to get Messages from channels that consumers are supposed
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to send on to verify that they did.
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You can even pass ``require=True`` to ``get_next_message`` to make the test
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fail if there is no message on the channel (by default, it will return you
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``None`` instead).
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Here's an extended example testing a consumer that's supposed to take a value
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and post the square of it to the ``"result"`` channel::
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from channels import Channel
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from channels.tests import ChannelTestCase
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class MyTests(ChannelTestCase):
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def test_a_thing(self):
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# Inject a message onto the channel to use in a consumer
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Channel("input").send({"value": 33})
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# Run the consumer with the new Message object
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my_consumer(self.get_next_message("input", require=True))
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# Verify there's a result and that it's accurate
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result = self.get_next_message("result", require=True)
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self.assertEqual(result['value'], 1089)
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Multiple Channel Layers
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-----------------------
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If you want to test code that uses multiple channel layers, specify the alias
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of the layers you want to mock as the ``test_channel_aliases`` attribute on
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the ``ChannelTestCase`` subclass; by default, only the ``default`` layer is
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mocked.
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You can pass an ``alias`` argument to ``get_next_message`` and ``Channel``
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to use a different layer too.
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