141 lines
4.7 KiB
Plaintext
141 lines
4.7 KiB
Plaintext
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.. highlightlang:: python
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.. _mysetup:
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mysetup pattern: application specific test fixtures
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==========================================================
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Here is a basic useful step-by-step example for managing and interacting
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with application specific test setup. The goal is to have one place
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where we have the glue and test support code for bootstrapping and
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configuring application objects and allow test modules and test
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functions to stay ignorant of involved details.
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step1: implementing the test/app-specific ``mysetup`` pattern
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-------------------------------------------------------------
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Let's write a simple test function using a ``mysetup`` funcarg::
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# content of test_sample.py
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def test_answer(mysetup):
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app = mysetup.myapp()
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answer = app.question()
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assert answer == 42
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To run this test py.test needs to find and call a factory to
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obtain the required ``mysetup`` function argument. To make
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an according factory findable we write down a specifically named factory
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method in a :ref:`local plugin`::
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# content of conftest.py
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from myapp import MyApp
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def pytest_funcarg__mysetup(request): # "mysetup" factory function
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return MySetup()
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class MySetup: # instances of this are seen by test functions
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def myapp(self):
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return MyApp()
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To run the example we stub out a a simple ``MyApp`` application object::
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# content of myapp.py
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class MyApp:
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def question(self):
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return 6 * 9
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You can now run the test::
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$ py.test test_sample.py
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=========================== test session starts ============================
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platform linux2 -- Python 2.6.5 -- pytest-2.0.0.dev30
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test path 1: test_sample.py
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test_sample.py F
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================================= FAILURES =================================
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_______________________________ test_answer ________________________________
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mysetup = <conftest.MySetup instance at 0x16f5998>
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def test_answer(mysetup):
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app = mysetup.myapp()
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answer = app.question()
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> assert answer == 42
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E assert 54 == 42
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test_sample.py:4: AssertionError
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========================= 1 failed in 0.02 seconds =========================
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This means that our ``mysetup`` object was successfully instantiated
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and ``mysetup.app()`` returned an initialized ``MyApp`` instance.
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We can ask it about the question and if you are confused as to what
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the concrete question or answers actually mean, please see here_.
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.. _here: http://uncyclopedia.wikia.com/wiki/The_Hitchhiker's_Guide_to_the_Galaxy
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.. _`tut-cmdlineoption`:
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step 2: checking a command line option and skipping tests
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-----------------------------------------------------------
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To add a command line option we update the ``conftest.py`` of
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the previous example to add a command line option
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and to offer a new mysetup method::
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# content of ./conftest.py
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import pytest
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from myapp import MyApp
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def pytest_funcarg__mysetup(request): # "mysetup" factory function
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return MySetup(request)
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def pytest_addoption(parser):
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parser.addoption("--ssh", action="store", default=None,
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help="specify ssh host to run tests with")
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class MySetup:
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def __init__(self, request):
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self.config = request.config
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def myapp(self):
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return MyApp()
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def getsshconnection(self):
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host = self.config.option.ssh
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if host is None:
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pytest.skip("specify ssh host with --ssh")
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return execnet.SshGateway(host)
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Now any test function can use the ``mysetup.getsshconnection()`` method
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like this::
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# content of test_ssh.py
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class TestClass:
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def test_function(self, mysetup):
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conn = mysetup.getsshconnection()
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# work with conn
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Running it yields::
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$ py.test test_ssh.py -rs
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=========================== test session starts ============================
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platform linux2 -- Python 2.6.5 -- pytest-2.0.0.dev30
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test path 1: test_ssh.py
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test_ssh.py s
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========================= short test summary info ==========================
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SKIP [1] /tmp/doc-exec-107/conftest.py:22: specify ssh host with --ssh
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======================== 1 skipped in 0.02 seconds =========================
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If you specify a command line option like ``py.test --ssh=python.org`` the test will execute as expected.
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Note that neither the ``TestClass`` nor the ``test_function`` need to
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know anything about how to setup the test state. It is handled separately
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in your "test setup glue" code in the ``conftest.py`` file. It is easy
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to extend the ``mysetup`` object for further needs in the test code - and for use by any other test functions in the files and directories below the ``conftest.py`` file.
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