Merge lp:~free.ekanayaka/python-fixtures/reusable-fixture into lp:~python-fixtures/python-fixtures/trunk

[Free Ekanayaka]

This an idea that came out from this MP:

https://code.launchpad.net/~free.ekanayaka/rabbitfixture/non-ephemeral/+merge/171117

you might want to read it for the full background.

In a nutshell: in case an expensive fixture can be re-used across different tests, projects can wrap it with ReusableFixture and have it setup/cleaned-up only once.

I've tried to understand if this could be done somehow with testresources (perhaps with the reset() method), but I couldn't figure that out. Comments are welcome.

[Robert Collins (lifeless)]

Hi, this is interesting.

So, testresources is aimed at this, grab me on IRC and I can debug
what's not working for you. If you're seeing setup/teardowns, you
don't have the optimiser working properly.

That said, we can do this thing you've got here, and I'll give it a
full review this week.

-Rob

Unmerged revisions

68. By Free Ekanayaka on 2013-06-26

Add ReusableFixture

=== modified file 'lib/fixtures/__init__.py'
--- lib/fixtures/__init__.py	2012-12-17 00:35:34 +0000
+++ lib/fixtures/__init__.py	2013-06-26 10:58:24 +0000
@@ -56,6 +56,7 @@
     'PopenFixture',
     'PythonPackage',
     'PythonPathEntry',
+    'ReusableFixture',
     'StringStream',
     'TempDir',
     'TempHomeDir',
@@ -85,6 +86,7 @@
     PopenFixture,
     PythonPackage,
     PythonPathEntry,
+    ReusableFixture,
     StringStream,
     TempDir,
     TempHomeDir,
 
=== modified file 'lib/fixtures/_fixtures/__init__.py'
--- lib/fixtures/_fixtures/__init__.py	2012-12-16 12:18:12 +0000
+++ lib/fixtures/_fixtures/__init__.py	2013-06-26 10:58:24 +0000
@@ -31,6 +31,7 @@
     'PopenFixture',
     'PythonPackage',
     'PythonPathEntry',
+    'ReusableFixture',
     'StringStream',
     'TempDir',
     'TempHomeDir',
@@ -56,6 +57,7 @@
 from fixtures._fixtures.packagepath import PackagePathEntry
 from fixtures._fixtures.pythonpackage import PythonPackage
 from fixtures._fixtures.pythonpath import PythonPathEntry
+from fixtures._fixtures.reusable import ReusableFixture
 from fixtures._fixtures.streams import (
     ByteStream,
     DetailStream,
 
=== added file 'lib/fixtures/_fixtures/reusable.py'
--- lib/fixtures/_fixtures/reusable.py	1970-01-01 00:00:00 +0000
+++ lib/fixtures/_fixtures/reusable.py	2013-06-26 10:58:24 +0000
@@ -0,0 +1,45 @@
+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Copyright (c) 2011, Robert Collins <[e-mail]>
+#
+# 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
+# project source as Apache-2.0 and BSD. You may not use this file except in
+# compliance with one of these two licences.
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under these licenses is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# license you chose for the specific language governing permissions and
+# limitations under that license.
+import atexit
+
+from fixtures import Fixture
+
+
+__all__ = [
+    'ReusableFixture',
+    ]
+
+
+class ReusableFixture(Fixture):
+    """Wrap a fixture that can be re-uased, cleaning it up at process exit.
+
+    This may save considerable time in set-up and tear-down.
+    """
+
+    def __init__(self, fixture):
+        """Wrap the given re-usable fixture.
+
+        :param fixture: The fixture being wrapped.
+        """
+        super(ReusableFixture, self).__init__()
+        self.fixture = fixture
+        self.count = 0
+
+    def setUp(self):
+        super(ReusableFixture, self).setUp()
+        if self.count == 0:
+            self.fixture.setUp()
+            atexit.register(self.fixture.cleanUp)
+        self.count += 1
 
=== added file 'lib/fixtures/tests/_fixtures/test_reusable.py'
--- lib/fixtures/tests/_fixtures/test_reusable.py	1970-01-01 00:00:00 +0000
+++ lib/fixtures/tests/_fixtures/test_reusable.py	2013-06-26 10:58:24 +0000
@@ -0,0 +1,61 @@
+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Copyright (c) 2011, Robert Collins <[e-mail]>
+#
+# 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
+# project source as Apache-2.0 and BSD. You may not use this file except in
+# compliance with one of these two licences.
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under these licenses is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# license you chose for the specific language governing permissions and
+# limitations under that license.
+import sys
+
+from testtools import TestCase
+
+from fixtures import (
+    ReusableFixture,
+    TestWithFixtures,
+    )
+
+
+class DummyFixture(object):
+
+    setups = 0
+    cleanups = 0
+
+    def setUp(self):
+        self.setups += 1
+
+    def cleanUp(self):
+        self.cleanups += 1
+
+
+class ReusableFixtureTest(TestCase, TestWithFixtures):
+
+    def setUp(self):
+        super(ReusableFixtureTest, self).setUp()
+
+    def test_reuse(self):
+        fixture = ReusableFixture(DummyFixture())
+
+        fixture.setUp()
+        fixture.cleanUp()
+        self.assertEqual(fixture.fixture.setups, 1)
+        self.assertEqual(fixture.fixture.cleanups, 0)
+
+        fixture.setUp()
+        fixture.cleanUp()
+        self.assertEqual(fixture.fixture.setups, 1)  # Still one setup
+        self.assertEqual(fixture.fixture.cleanups, 0)  # Still no cleanups
+
+        self.assertEqual(fixture.count, 2)
+
+    def test_atexit(self):
+        fixture = ReusableFixture(DummyFixture())
+        fixture.setUp()
+        sys.exitfunc()
+        self.assertEqual(fixture.fixture.cleanups, 1)