diff options
-rw-r--r-- | NEWS | 6 | ||||
-rw-r--r-- | README | 29 | ||||
-rw-r--r-- | lib/testscenarios/scenarios.py | 36 | ||||
-rw-r--r-- | lib/testscenarios/tests/test_scenarios.py | 18 |
4 files changed, 87 insertions, 2 deletions
@@ -9,6 +9,12 @@ IN DEVELOPMENT 0.2 ~~~ +NEW FEATURES: + +* New function ``per_module_scenarios`` for tests that should be applied across + multiple modules providing the same interface, some of which may not be + available at run time. (Martin Pool) + CHANGES: * Adjust the cloned tests ``shortDescription`` if one is present. (Ben Finney) @@ -258,6 +258,35 @@ allowing it to be used to layer scenarios without affecting existing scenario selection. +Generating Scenarios +==================== + +Some functions (currently one :-) are available to ease generation of scenario +lists for common situations. + +Testing Per Implementation Module ++++++++++++++++++++++++++++++++++ + +It is reasonably common to have multiple Python modules that provide the same +capabilities and interface, and to want apply the same tests to all of them. + +In some cases, not all of the statically defined implementations will be able +to be used in a particular testing environment. For example, there may be both +a C and a pure-Python implementation of a module. You want to test the C +module if it can be loaded, but also to have the tests pass if the C module has +not been compiled. + +The ``per_module_scenarios`` function generates a scenario for each named +module, omitting those that raise an ``ImportError``. For each test object, +the implementation to be tested is installed into a given attribute. + +Note that for the test to be valid, all access to the module under test must go +through the relevant attribute of the test object. If one of the +implementations is also directly imported by the test module or any other, +testscenarios will not magically stop it being used. + + + Advice on Writing Scenarios =========================== diff --git a/lib/testscenarios/scenarios.py b/lib/testscenarios/scenarios.py index 80847d6..e052c22 100644 --- a/lib/testscenarios/scenarios.py +++ b/lib/testscenarios/scenarios.py @@ -2,7 +2,7 @@ # dependency injection ('scenarios') by tests. # # Copyright (c) 2009, Robert Collins <robertc@robertcollins.net> -# Copyright (c) 2010 Martin Pool <mbp@sourcefrog.net> +# Copyright (c) 2010, 2011 Martin Pool <mbp@sourcefrog.net> # # Licensed under either the Apache License, Version 2.0 or the BSD 3-clause # license at the users choice. A copy of both licenses are available in the @@ -129,3 +129,37 @@ def multiply_scenarios(*scenarios): scenario_parameters.update(parameter) result.append((scenario_name, scenario_parameters)) return result + + +def per_module_scenarios(attribute_name, modules): + """Generate scenarios for available implementation modules. + + This is typically used when there is a subsystem implemented, for + example, in both Python and C, and we want to apply the same tests to + both, but the C module may sometimes not be available. + + Note: if the module can't be loaded, it's silently omitted from + testing. + + :param attribute_name: A name to be set in the scenario parameter + dictionary (and thence onto the test instance) pointing to the + implementation module for this scenario. + + :param modules: An iterable of (short_name, module_name), where + the short name is something like 'python' to put in the + scenario name, and the long name is a fully-qualified Python module + name. + """ + scenarios = [] + for short_name, module_name in modules: + try: + mod = __import__(module_name, {}, {}, ['']) + except ImportError: + # TODO: optionally pass this back through a callback, so it can be + # logged etc? + pass + else: + scenarios.append(( + short_name, + {attribute_name: mod})) + return scenarios diff --git a/lib/testscenarios/tests/test_scenarios.py b/lib/testscenarios/tests/test_scenarios.py index 063df51..1fe12ed 100644 --- a/lib/testscenarios/tests/test_scenarios.py +++ b/lib/testscenarios/tests/test_scenarios.py @@ -2,7 +2,7 @@ # dependency injection ('scenarios') by tests. # # Copyright (c) 2009, Robert Collins <robertc@robertcollins.net> -# Copyright (c) 2010 Martin Pool <mbp@sourcefrog.net> +# Copyright (c) 2010, 2011 Martin Pool <mbp@sourcefrog.net> # # Licensed under either the Apache License, Version 2.0 or the BSD 3-clause # license at the users choice. A copy of both licenses are available in the @@ -239,3 +239,19 @@ class TestMultiplyScenarios(testtools.TestCase): self.assertEqual( 'a,a,a,a', scenarios[0][0]) + + +class TestPerModuleScenarios(testtools.TestCase): + + def test_per_module_scenarios(self): + """Generate scenarios for available modules""" + s = testscenarios.scenarios.per_module_scenarios( + 'the_module', [ + ('Python', 'testscenarios'), + ('unittest', 'unittest'), + ('nonexistent', 'nonexistent'), + ]) + self.assertEqual(s, [ + ('Python', {'the_module': testscenarios}), + ('unittest', {'the_module': unittest}), + ]) |