[py-dev] Testing publish-subscribe apps

[holger krekel]

Hi Michael, 

On Fri, Feb 16, 2007 at 21:58 -0600, Michael Hipp wrote:
> In my previous question I asked about testing applications that use a 
> publish-subscribe mechanism. I've done a simple app and tester to prove I can 
> make it work. I'm posting it here in case it might help someone else. I'd also 
> like to invite critique as this is my first attempt at using py.test. (I'll be 
> doing a *lot* of this when I test my real application.)
> 
> Thanks,
> Michael
> 
> --- The app being tested --------------------------------
> # FILE: myapp.py
> 
> from wx.lib.pubsub import Publisher
> 
> myTestTopic = "my_test_topic"  # A publisher topic
> 
> def DoSomething():
>      # Send a message with a tuple of data
>      Publisher.sendMessage(myTestTopic, (1,2,3))
> --- The app being tested --------------------------------
> # FILE: test_myapp.py
> 
> from wx.lib.pubsub import Publisher  # wxPython publish-subscribe module
> from myapp import DoSomething, myTestTopic  # myapp.py
> 
> # If someone can tell me how to not need these module-level
> #    globals I'm all ears
> gotTestTopic = False  # Indicates we received the test topic message
> testTopicData = None  # The data we got with the test topic message
> 
> def setup_module(module):
>      '''This sets certain state specific to the execution of this module.'''
>      # Subscribe to the test topic message
>      Publisher.subscribe(TestTopicReceiver, myTestTopic)

a few notes: 

* i have no clue about wxpython :) 

* I prefer to have test and code-being-tested separate from
  each other, so myTestTopic would be better to live in the
  testfile.  

* i guess you can avoid module globals by using test classes
  (see e.g. http://codespeak.net/py/dist/test.html#id17)

  maybe something like (untested): 

    class TestMyApp:
        def setup_method(self, method):
            self.topic = "my_test_topic" # + method.__name__
            self.received = []
            Publisher.subscribe(self.topic, self.received.append)

        def teardown_method(self, method):  
            # don't know if wx has it: 
            Publisher.unsubscribe(self.topic, self.received.append)

        def test_dosomething(self):
            assert not self.received 
            DoSomething()
            assert len(self.received) == 1
            msg = self.received[0]
            assert msg.topic == self.topic
            assert len(msg.data) == 3 # and so one
           
hope it helps, have fun,

holger
             

> def test_DoSomething():
>      assert not gotTestTopic       # Make sure there is no trickery
>      assert testTopicData is None
>      DoSomething()  # This is "myapp"
>      assert gotTestTopic             # Now we should have it
>      assert len(testTopicData) == 3  # Verify the data also
> 
> def TestTopicReceiver(msg):
>      '''Receives the test topic message and sets global vars to be read in
>      the test routine.'''
>      global gotTestTopic, testTopicData
>      if msg.topic[0] == myTestTopic:  # Make sure it's really our topic
>          gotTestTopic = True
>          testTopicData = msg.data     # The data payload in the msg
> 
> --- End ----
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> 

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