[Zope-dev] Re: New test runner work
Stuart Bishop wrote: Jim Fulton wrote: A large proportion of our tests use a relational database. Some of them want an empty database, some of them want just the schema created but no data, some of them want the schema created and the data. Some of them need the component architecture, and some of them don't. Some of them need one or more twisted servers running, some of them don't. Note that we mix and match. We have 4 different types of database fixture (none, empty, schema, populated), 2 different types of database connection mechanisms (psycopgda, psycopg), 2 types of CA fixture (none, loaded), and (currently) 4 states of external daemons needed. If we were to arrange this in layers, it would take 56 different layers, and this will double every time we add a new daemon, or add more database templates (e.g. fat for lots of sample data to go with the existing thin). As a way of supporting this better, instead of specifying a layer a test could specify the list of resources it needs: import testresources as r class FooTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian, r.Component] [...] class BarTest(unittest.TestCase): resources = [r.EmptyDb] class BazTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian] This is pretty much how layers work. Layers can be arranged in a DAG (much like a traditional multiple-inheritence class graph). So, you can model each resource as a layer and specific combinations of resources as layers. The test runner will attempt to run the layers in an order than minimizes set-up and tear-down of layers. So my example could be modeled using layers like: import layers as l class FooLayer(l.LaunchpadDb, l.Librarian, l.Component): pass class FooTest(unittest.TestCase): layer = 'FooLayer' [...] class BarLayer(l.LaunchpadDb, l.Librarian, l.Component): pass class BarTest(unitest.TestCase): layer = 'BarLayer' [...] class BazLayer(l.LaunchpadDb, l.Librarian): pass class BazTest(unittest.TestCase): layer = 'BazLayer' [...] In general I would need to define a layer for each test case (because the number of combinations make it impractical to explode all the possible combinations into a tree of layers, if for no other reason than naming them). That's too bad. Perhaps layers don't fit your need then. If I tell the test runner to run all the tests, will the LaunchpadDb, Librarian and Component layers each be initialized just once? If all of the tests means these 3, then yes. If I tell the test runner to run the Librarian layer tests, will all three tests be run? No, no tests will be run. None of the tests are in the librarian layer. They are in layers build on the librarian layer. What happens if I go and define a new test: class LibTest(unittest.TestCase): layer = 'l.Librarian' [...] If I run all the tests, will the Librarian setup/teardown be run once (by running the tests in the order LibTest, BazTest, FooTest, BarTest and initializing the Librarian layer before the LaunchpadDb layer)? Yes I expect not, as 'layer' indicates a heirarchy which isn't as useful to me as a set of resources. I don't follow this. If layers don't work this way, it might be possible to emulate resources somehow: If each test *really* has a unique set of resources, then perhaps laters don't fit. class ResourceTest(unittest.TestCase): @property def layer(self): return type(optimize_order(self.resources)) Howver, optimize_order would need to know about all the other tests so would really be the responsibility of the test runner (so it would need to be customized/overridden), and the test runner would need to support the layer attribute possibly being a class rather than a string. Layers can be classes. In fact, I typically use classes with class methods for setUp and tearDown. Ah, so the layer specifies additional per-test setUp and tearDown that is used in addition to the tests's own setUp and tearDown. This sounds reasonable. But what to call them? setUpPerTest? The pretest and posttest names I used are a bit sucky. shrug testSetUp? On another note, enforcing isolation of tests has been a continuous problem for us. For example, a developer registering a utility or otherwise mucking around with the global environment and forgetting to reset things in tearDown. This goes unnoticed for a while, and other tests get written that actually depend on this corruption. But at some point, the order the tests are run changes for some reason and suddenly test 500 starts failing. It turns out the global state has been screwed, and you have the fun task of tracking down which of the proceeding 499 tests screwed it. I think this is a use case for some sort of global posttest hook. How so? In order to diagnose the problem I describe (which has happened far too often!), you would add a posttest check that is run after each test. The first test that fails due to this check is the
[Zope-dev] Re: New test runner work
Jim Fulton wrote: I'll note that I'm working on a newer test runner that I hope to use in Zope 2.9 and 3.2. The new test runner is a nearly complete rewrite to provide: - A more flexible test runner that can be used for a variety of projects. The current test runner has been forked for ZODB, Zope 3, and Zope 2. That's why the Zope 3 version has features that are lacking in the Zope 2 version. - Support for layers of tests, so that it can handle unit tests and functional tests. - A slightly better UI. - Tests (of the test runner itself :) See: http://svn.zope.org/zope.testing/trunk/src/zope/testing/testrunner.txt?view=log http://svn.zope.org/zope.testing/trunk/src/zope/testing/testrunner.py?view=log Hi Jim. I've been looking over this - fixing tests seems to take up a significant amount of our time, so I might have some interesting use cases. A large proportion of our tests use a relational database. Some of them want an empty database, some of them want just the schema created but no data, some of them want the schema created and the data. Some of them need the component architecture, and some of them don't. Some of them need one or more twisted servers running, some of them don't. Note that we mix and match. We have 4 different types of database fixture (none, empty, schema, populated), 2 different types of database connection mechanisms (psycopgda, psycopg), 2 types of CA fixture (none, loaded), and (currently) 4 states of external daemons needed. If we were to arrange this in layers, it would take 56 different layers, and this will double every time we add a new daemon, or add more database templates (e.g. fat for lots of sample data to go with the existing thin). As a way of supporting this better, instead of specifying a layer a test could specify the list of resources it needs: import testresources as r class FooTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian, r.Component] [...] class BarTest(unittest.TestCase): resources = [r.EmptyDb] class BazTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian] The resources are pretty much identical to the current layers, in that (after the test runner does some sorting fu), the run order can be optimized to avoid setting up and tearing down resources unnecessarily. This would be a big win for us - currently, we specify 'resources' by simply calling various setup and teardown methods in the test case: class FooTest(unittest.TestCase): def setUp(self): LaunchpadTestSetup().setUp() LibrarianTestSetup().setUp() FunctionalTestSetup().setUp() def tearDown(self): FunctionalTestSetup().tearDown() LibrarianTestSetup().tearDown() LaunchpadTestSetup().tearDown() Some other nice things could be done with the resources: - If the setUp raises NotImplementedError (or whatever), tests using this resource are skipped (and reported as skipped). This nicely handles tests that should only be run in particular environments (Win32, Internet connection, python.net installed etc.) - If the setUp raises another exception, all tests using this resource fail. The common case we see is 'database in use', where PostgreSQL does not let us destroy or use as a template a database that has open connections to it. Also useful for general sanity checking of the environment - no point running the tests if we know they are going to fail or have skewed results. - A resource should have a pretest and posttest hooks. pretest is used for lightweight resource specific initialization (e.g. setUp creates a fresh database from a dump and pretest initializes the connection pool). posttest can be used to ensure tests cleaned up properly or other housekeeping (e.g. issuing a rollback). This could also apply to layers in the current environment. This eliminates tedious boilerplate from testcases. - A resource could provide useful data to the test runner. For example, if a resource says it doesn't use or lock any shared system resources, the test runner could decide to run tests in parallel. Although a less blue sky use would be specifying a dependancy on another resource. On another note, enforcing isolation of tests has been a continuous problem for us. For example, a developer registering a utility or otherwise mucking around with the global environment and forgetting to reset things in tearDown. This goes unnoticed for a while, and other tests get written that actually depend on this corruption. But at some point, the order the tests are run changes for some reason and suddenly test 500 starts failing. It turns out the global state has been screwed, and you have the fun task of tracking down which of the proceeding 499 tests screwed it. I think this is a use case for some sort of global posttest hook. Perhaps this would be best done by allowing people to write wrappers around the one-true-testrunner? This seems to be the simplest way of allowing
[Zope-dev] Re: New test runner work
Stuart Bishop wrote: Jim Fulton wrote: I'll note that I'm working on a newer test runner that I hope to use in Zope 2.9 and 3.2. The new test runner is a nearly complete rewrite to provide: - A more flexible test runner that can be used for a variety of projects. The current test runner has been forked for ZODB, Zope 3, and Zope 2. That's why the Zope 3 version has features that are lacking in the Zope 2 version. - Support for layers of tests, so that it can handle unit tests and functional tests. - A slightly better UI. - Tests (of the test runner itself :) See: http://svn.zope.org/zope.testing/trunk/src/zope/testing/testrunner.txt?view=log http://svn.zope.org/zope.testing/trunk/src/zope/testing/testrunner.py?view=log Hi Jim. I've been looking over this - fixing tests seems to take up a significant amount of our time, so I might have some interesting use cases. A large proportion of our tests use a relational database. Some of them want an empty database, some of them want just the schema created but no data, some of them want the schema created and the data. Some of them need the component architecture, and some of them don't. Some of them need one or more twisted servers running, some of them don't. Note that we mix and match. We have 4 different types of database fixture (none, empty, schema, populated), 2 different types of database connection mechanisms (psycopgda, psycopg), 2 types of CA fixture (none, loaded), and (currently) 4 states of external daemons needed. If we were to arrange this in layers, it would take 56 different layers, and this will double every time we add a new daemon, or add more database templates (e.g. fat for lots of sample data to go with the existing thin). As a way of supporting this better, instead of specifying a layer a test could specify the list of resources it needs: import testresources as r class FooTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian, r.Component] [...] class BarTest(unittest.TestCase): resources = [r.EmptyDb] class BazTest(unittest.TestCase): resources = [r.LaunchpadDb, r.Librarian] This is pretty much how layers work. Layers can be arranged in a DAG (much like a traditional multiple-inheritence class graph). So, you can model each resource as a layer and specific combinations of resources as layers. The test runner will attempt to run the layers in an order than minimizes set-up and tear-down of layers. ... Some other nice things could be done with the resources: - If the setUp raises NotImplementedError (or whatever), tests using this resource are skipped (and reported as skipped). This nicely handles tests that should only be run in particular environments (Win32, Internet connection, python.net installed etc.) That's a good idea. - If the setUp raises another exception, all tests using this resource fail. The common case we see is 'database in use', where PostgreSQL does not let us destroy or use as a template a database that has open connections to it. Also useful for general sanity checking of the environment - no point running the tests if we know they are going to fail or have skewed results. Good. - A resource should have a pretest and posttest hooks. pretest is used for lightweight resource specific initialization (e.g. setUp creates a fresh database from a dump and pretest initializes the connection pool). posttest can be used to ensure tests cleaned up properly or other housekeeping (e.g. issuing a rollback). This could also apply to layers in the current environment. This eliminates tedious boilerplate from testcases. Ah, so the layer specifies additional per-test setUp and tearDown that is used in addition to the tests's own setUp and tearDown. This sounds reasonable. - A resource could provide useful data to the test runner. For example, if a resource says it doesn't use or lock any shared system resources, the test runner could decide to run tests in parallel. Although a less blue sky use would be specifying a dependancy on another resource. This is handled by layers now. Layers have __bases__ -- layers are build on other layers. That's why they are caled layers. :) On another note, enforcing isolation of tests has been a continuous problem for us. For example, a developer registering a utility or otherwise mucking around with the global environment and forgetting to reset things in tearDown. This goes unnoticed for a while, and other tests get written that actually depend on this corruption. But at some point, the order the tests are run changes for some reason and suddenly test 500 starts failing. It turns out the global state has been screwed, and you have the fun task of tracking down which of the proceeding 499 tests screwed it. I think this is a use case for some sort of global posttest hook. How so? Perhaps this would be best done by allowing people to write wrappers around the one-true-testrunner? or we could simply provide such a
