New fixture ``PackagePathEntry`` which patches the path of an existing

package, allowing importing part of it from aonther directory.
(Robert Collins)

7 files changed, 111 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 82f5d09..e0a17ec 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,10 @@ CHANGES:
   gather_details helper).
   (Gavin Panella, #796253)
 
+* New fixture ``PackagePathEntry`` which patches the path of an existing
+  package, allowing importing part of it from aonther directory.
+  (Robert Collins)
+
 * New fixture ``PythonPathEntry`` which patches sys.path.
   (Robert Collins, #737503)
 
diff --git a/README b/README
index 00b7327..84680d9 100644
--- a/README
+++ b/README
@@ -283,6 +283,15 @@ Control the value of a named python attribute.
   ...     pass
   >>> fixture = fixtures.MonkeyPatch('__builtin__.open', fake_open)
 
+PackagePathEntry
+++++++++++++++++
+
+Adds a single directory to the path for an existing python package. This adds
+to the package.__path__ list. If the directory is already in the path, nothing
+happens, if it isn't then it is added on setUp and removed on cleanUp.
+
+  >>> fixture = fixtures.PackagePathEntry('package/name', '/foo/bar')
+
 PopenFixture
 ++++++++++++
 
diff --git a/lib/fixtures/__init__.py b/lib/fixtures/__init__.py
index 1729a9e..a697680 100644
--- a/lib/fixtures/__init__.py
+++ b/lib/fixtures/__init__.py
@@ -44,6 +44,7 @@ __all__ = [
     'FunctionFixture',
     'MethodFixture',
     'MonkeyPatch',
+    'PackagePathEntry',
     'PopenFixture',
     'PythonPackage',
     'PythonPathEntry',
@@ -56,6 +57,7 @@ from fixtures.fixture import Fixture, FunctionFixture, MethodFixture
 from fixtures._fixtures import (
     EnvironmentVariableFixture,
     MonkeyPatch,
+    PackagePathEntry,
     PopenFixture,
     PythonPackage,
     PythonPathEntry,
diff --git a/lib/fixtures/_fixtures/__init__.py b/lib/fixtures/_fixtures/__init__.py
index b18775c..6287242 100644
--- a/lib/fixtures/_fixtures/__init__.py
+++ b/lib/fixtures/_fixtures/__init__.py
@@ -19,6 +19,7 @@
 __all__ = [
     'EnvironmentVariableFixture',
     'MonkeyPatch',
+    'PackagePathEntry',
     'PopenFixture',
     'PythonPackage',
     'PythonPathEntry',
@@ -29,6 +30,7 @@ __all__ = [
 from fixtures._fixtures.environ import EnvironmentVariableFixture
 from fixtures._fixtures.monkeypatch import MonkeyPatch
 from fixtures._fixtures.popen import PopenFixture
+from fixtures._fixtures.packagepath import PackagePathEntry
 from fixtures._fixtures.pythonpackage import PythonPackage
 from fixtures._fixtures.pythonpath import PythonPathEntry
 from fixtures._fixtures.tempdir import TempDir
diff --git a/lib/fixtures/_fixtures/packagepath.py b/lib/fixtures/_fixtures/packagepath.py
new file mode 100644
index 0000000..43a9bf3
--- /dev/null
+++ b/lib/fixtures/_fixtures/packagepath.py
@@ -0,0 +1,48 @@
+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Copyright (c) 2011, Robert Collins <robertc@robertcollins.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
+# 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.
+
+__all__ = [
+    'PackagePathEntry'
+    ]
+
+import sys
+
+from fixtures import Fixture
+
+
+class PackagePathEntry(Fixture):
+    """Add a path to the path of a python package.
+
+    The python package needs to be already imported.
+
+    If this new path is already in the packages __path__ list then the __path__
+    list will not be altered.
+    """
+
+    def __init__(self, packagename, directory):
+        """Create a PackagePathEntry.
+
+        :param directory: The directory to add to the package.__path__.
+        """
+        self.packagename = packagename
+        self.directory = directory
+
+    def setUp(self):
+        Fixture.setUp(self)
+        path = sys.modules[self.packagename].__path__
+        if self.directory in path:
+            return
+        self.addCleanup(path.remove, self.directory)
+        path.append(self.directory)
diff --git a/lib/fixtures/tests/_fixtures/__init__.py b/lib/fixtures/tests/_fixtures/__init__.py
index f5dfeef..e41bcc7 100644
--- a/lib/fixtures/tests/_fixtures/__init__.py
+++ b/lib/fixtures/tests/_fixtures/__init__.py
@@ -17,6 +17,7 @@ def load_tests(loader, standard_tests, pattern):
     test_modules = [
         'environ',
         'monkeypatch',
+        'packagepath',
         'popen',
         'pythonpackage',
         'pythonpath',
diff --git a/lib/fixtures/tests/_fixtures/test_packagepath.py b/lib/fixtures/tests/_fixtures/test_packagepath.py
new file mode 100644
index 0000000..fd52194
--- /dev/null
+++ b/lib/fixtures/tests/_fixtures/test_packagepath.py
@@ -0,0 +1,45 @@
+#  fixtures: Fixtures with cleanups for testing and convenience.
+#
+# Copyright (c) 2011, Robert Collins <robertc@robertcollins.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
+# 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
+
+import testtools
+
+import fixtures
+from fixtures import (
+    PackagePathEntry,
+    TempDir,
+    )
+
+
+class TestPackagePathEntry(testtools.TestCase):
+
+    def test_adds_missing_to_end_package_path(self):
+        uniquedir = self.useFixture(TempDir()).path
+        fixture = PackagePathEntry('fixtures', uniquedir)
+        self.assertFalse(uniquedir in fixtures.__path__)
+        with fixture:
+            self.assertTrue(uniquedir in fixtures.__path__)
+        self.assertFalse(uniquedir in fixtures.__path__)
+
+    def test_doesnt_alter_existing_entry(self):
+        existingdir = fixtures.__path__[0]
+        expectedlen = len(fixtures.__path__)
+        fixture = PackagePathEntry('fixtures', existingdir)
+        with fixture:
+            self.assertTrue(existingdir in fixtures.__path__)
+            self.assertEqual(expectedlen, len(fixtures.__path__))
+        self.assertTrue(existingdir in fixtures.__path__)
+        self.assertEqual(expectedlen, len(fixtures.__path__))