Implement an adapter for existing fixtures that honour a setUp/tearDown like protocol.

3 files changed, 107 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 37d91f9..2a5e4be 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,9 @@ CHANGES
 IMPROVEMENTS
 ~~~~~~~~~~~~
 
+* New helper testresources.GenericResource which should remove the need for
+  much boilerplate when using testresources with existing test fixtures.
+
 BUG FIXES
 ~~~~~~~~~
 
diff --git a/lib/testresources/__init__.py b/lib/testresources/__init__.py
index b9854a5..859584b 100644
--- a/lib/testresources/__init__.py
+++ b/lib/testresources/__init__.py
@@ -17,6 +17,8 @@
 #  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #
 
+"""TestResources: declarative management of external resources for tests."""
+
 import inspect
 import unittest
 
@@ -354,6 +356,48 @@ class TestResource(object):
         self._dirty = False
 
 
+class GenericResource(TestResource):
+    """A TestResource that decorates an external helper of some kind.
+
+    GenericResource can be used to adapt an external resource so that 
+    testresources can use it. By default the setUp and tearDown methods are
+    called when making and cleaning the resource, and the resource is 
+    considered permanently dirty, so it is torn down and brought up again
+    between every use.
+
+    The constructor method is called with the dependency resources dict::
+        resource_factory(**dependency_resources)
+    This permits naming those resources to match the contract of the setUp
+    method.
+    """
+
+    def __init__(self, resource_factory, setup_method_name='setUp',
+        teardown_method_name='tearDown'):
+        """Create a GenericResource
+
+        :param resource_factory: A factory to create a new resource.
+        :param setup_method_name: Optional method name to call to setup the
+            resource. Defaults to 'setUp'.
+        :param teardown_method_name: Optional method name to call to tear down
+            the resource. Defaults to 'tearDown'.
+        """
+        TestResource.__init__(self)
+        self.resource_factory = resource_factory
+        self.setup_method_name = setup_method_name
+        self.teardown_method_name = teardown_method_name
+
+    def clean(self, resource):
+        getattr(resource, self.teardown_method_name)()
+
+    def make(self, dependency_resources):
+        result = self.resource_factory(**dependency_resources)
+        getattr(result, self.setup_method_name)()
+        return result
+
+    def isDirty(self):
+        return True
+
+
 class ResourcedTestCase(unittest.TestCase):
     """A TestCase parent or utility that enables cross-test resource usage.
 
diff --git a/lib/testresources/tests/test_test_resource.py b/lib/testresources/tests/test_test_resource.py
index e0d1ec4..70e8921 100644
--- a/lib/testresources/tests/test_test_resource.py
+++ b/lib/testresources/tests/test_test_resource.py
@@ -389,3 +389,63 @@ class TestTestResource(testtools.TestCase):
         resource_manager.finishedWith(r)
         resource_manager.finishedWith(resource_manager._currentResource)
         self.assertEqual(expected, result._calls)
+
+
+class TestGenericResource(testtools.TestCase):
+
+    def test_default_uses_setUp_tearDown(self):
+        calls = []
+        class Wrapped:
+            def setUp(self):
+                calls.append('setUp')
+            def tearDown(self):
+                calls.append('tearDown')
+        mgr = testresources.GenericResource(Wrapped)
+        resource = mgr.getResource()
+        self.assertEqual(['setUp'], calls)
+        mgr.finishedWith(resource)
+        self.assertEqual(['setUp', 'tearDown'], calls)
+        self.assertIsInstance(resource, Wrapped)
+
+    def test_dependencies_passed_to_factory(self):
+        calls = []
+        class Wrapped:
+            def __init__(self, **args):
+                calls.append(args)
+            def setUp(self):pass
+            def tearDown(self):pass
+        class Trivial(testresources.TestResource):
+            def __init__(self, thing):
+                testresources.TestResource.__init__(self)
+                self.thing = thing
+            def make(self, dependency_resources):return self.thing
+            def clean(self, resource):pass
+        mgr = testresources.GenericResource(Wrapped)
+        mgr.resources = [('foo', Trivial('foo')), ('bar', Trivial('bar'))]
+        resource = mgr.getResource()
+        self.assertEqual([{'foo':'foo', 'bar':'bar'}], calls)
+        mgr.finishedWith(resource)
+
+    def test_setup_teardown_controllable(self):
+        calls = []
+        class Wrapped:
+            def start(self):
+                calls.append('setUp')
+            def stop(self):
+                calls.append('tearDown')
+        mgr = testresources.GenericResource(Wrapped,
+            setup_method_name='start', teardown_method_name='stop')
+        resource = mgr.getResource()
+        self.assertEqual(['setUp'], calls)
+        mgr.finishedWith(resource)
+        self.assertEqual(['setUp', 'tearDown'], calls)
+        self.assertIsInstance(resource, Wrapped)
+
+    def test_always_dirty(self):
+        class Wrapped:
+            def setUp(self):pass
+            def tearDown(self):pass
+        mgr = testresources.GenericResource(Wrapped)
+        resource = mgr.getResource()
+        self.assertTrue(mgr.isDirty())
+        mgr.finishedWith(resource)