Merge pkg_resource_overrides branch.

7 files changed, 524 insertions, 6 deletions

diff --git a/repoze/bfg/includes/meta.zcml b/repoze/bfg/includes/meta.zcml
index 4acdfe937..ba0fc50cc 100644
--- a/repoze/bfg/includes/meta.zcml
+++ b/repoze/bfg/includes/meta.zcml
@@ -34,6 +34,12 @@
       handler="repoze.bfg.zcml.route"
       />
 
+  <meta:directive
+      name="resource"
+      schema="repoze.bfg.zcml.IResourceDirective"
+      handler="repoze.bfg.zcml.resource"
+      />
+
   </meta:directives>
 
 </configure>
diff --git a/repoze/bfg/interfaces.py b/repoze/bfg/interfaces.py
index 432c645a4..779c0ef03 100644
--- a/repoze/bfg/interfaces.py
+++ b/repoze/bfg/interfaces.py
@@ -231,6 +231,9 @@ class IRequestFactories(Interface):
     """ Marker utility interface representing a dictionary of request
     factory descriptions"""
 
+class IPackageOverrides(Interface):
+    """ Utility for pkg_resources overrides """
+
 # VH_ROOT_KEY is an interface; its imported from other packages (e.g.
 # traversalwrapper)
 VH_ROOT_KEY = 'HTTP_X_VHM_ROOT' 
diff --git a/repoze/bfg/resource.py b/repoze/bfg/resource.py
new file mode 100644
index 000000000..00e30170d
--- /dev/null
+++ b/repoze/bfg/resource.py
@@ -0,0 +1,106 @@
+import pkg_resources
+from zope.component import queryUtility
+from zope.interface import implements
+
+from repoze.bfg.interfaces import IPackageOverrides
+
+class OverrideProvider(pkg_resources.DefaultProvider):
+    def __init__(self, module):
+        pkg_resources.DefaultProvider.__init__(self, module)
+        self.module_name = module.__name__
+
+    def _get_overrides(self):
+        overrides = queryUtility(IPackageOverrides, self.module_name)
+        return overrides
+    
+    def get_resource_filename(self, manager, resource_name):
+        """ Return a true filesystem path for resource_name,
+        co-ordinating the extraction with manager, if the resource
+        must be unpacked to the filesystem.
+        """
+        overrides = self._get_overrides()
+        if overrides is not None:
+            filename = overrides.get_filename(resource_name)
+            if filename is not None:
+                return filename
+        return pkg_resources.DefaultProvider.get_resource_filename(
+            self, manager, resource_name)
+    
+    def get_resource_stream(self, manager, resource_name):
+        """ Return a readable file-like object for resource_name."""
+        overrides = self._get_overrides()
+        if overrides is not None:
+            stream =  overrides.get_stream(resource_name)
+            if stream is not None:
+                return stream
+        return pkg_resources.DefaultProvider.get_resource_stream(
+            self, manager, resource_name)
+
+    def get_resource_string(self, manager, resource_name):
+        """ Return a string containing the contents of resource_name."""
+        overrides = self._get_overrides()
+        if overrides is not None:
+            string = overrides.get_string(resource_name)
+            if string is not None:
+                return string
+        return pkg_resources.DefaultProvider.get_resource_string(
+            self, manager, resource_name)
+
+class PackageOverrides:
+    implements(IPackageOverrides)
+    def __init__(self, overridden_package):
+        self.overrides = []
+        self.overridden_package = overridden_package
+
+    def insert(self, path, package, prefix):
+        if path.endswith('/'):
+            override = DirectoryOverride(path, package, prefix)
+        else:
+            override = FileOverride(path, package, prefix)
+        self.overrides.insert(0, override)
+        return override
+
+    def search_path(self, resource_name):
+        for override in self.overrides:
+            o = override(resource_name)
+            if o is not None:
+                package, name = o
+                yield package, name
+
+    def get_filename(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_filename(package, rname)
+
+    def get_stream(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_stream(package, rname)
+
+    def get_string(self, resource_name):
+        for package, rname in self.search_path(resource_name):
+            if pkg_resources.resource_exists(package, rname):
+                return pkg_resources.resource_string(package, rname)
+
+class DirectoryOverride:
+    def __init__(self, path, package, prefix):
+        self.path = path
+        self.package = package
+        self.prefix = prefix
+        self.pathlen = len(self.path)
+
+    def __call__(self, resource_name):
+        if resource_name.startswith(self.path):
+            name = '%s%s' % (self.prefix, resource_name[self.pathlen:])
+            return self.package, name
+
+class FileOverride:
+    def __init__(self, path, package, prefix):
+        self.path = path
+        self.package = package
+        self.prefix = prefix
+
+    def __call__(self, resource_name):
+        if resource_name == self.path:
+            return self.package, self.prefix
+
diff --git a/repoze/bfg/tests/test_resource.py b/repoze/bfg/tests/test_resource.py
new file mode 100644
index 000000000..176a07049
--- /dev/null
+++ b/repoze/bfg/tests/test_resource.py
@@ -0,0 +1,237 @@
+import unittest
+from repoze.bfg.testing import cleanUp
+
+class TestOverrideProvider(unittest.TestCase):
+    def setUp(self):
+        cleanUp()
+
+    def tearDown(self):
+        cleanUp()
+
+    def _getTargetClass(self):
+        from repoze.bfg.resource import OverrideProvider
+        return OverrideProvider
+
+    def _makeOne(self, module):
+        klass = self._getTargetClass()
+        return klass(module)
+
+    def _registerOverrides(self, overrides, name='repoze.bfg.tests'):
+        from repoze.bfg.interfaces import IPackageOverrides
+        from zope.component import getSiteManager
+        sm = getSiteManager()
+        sm.registerUtility(overrides, IPackageOverrides, name=name)
+
+    def test_get_resource_filename_no_overrides(self):
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = os.path.join(here, resource_name)
+        result = provider.get_resource_filename(None, resource_name)
+        self.assertEqual(result, expected)
+
+    def test_get_resource_stream_no_overrides(self):
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = open(os.path.join(here, resource_name)).read()
+        result = provider.get_resource_stream(None, resource_name)
+        self.assertEqual(result.read(), expected)
+
+    def test_get_resource_string_no_overrides(self):
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = open(os.path.join(here, resource_name)).read()
+        result = provider.get_resource_string(None, resource_name)
+        self.assertEqual(result, expected)
+
+    def test_get_resource_filename_override_returns_None(self):
+        overrides = DummyOverrides(None)
+        self._registerOverrides(overrides)
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = os.path.join(here, resource_name)
+        result = provider.get_resource_filename(None, resource_name)
+        self.assertEqual(result, expected)
+        
+    def test_get_resource_stream_override_returns_None(self):
+        overrides = DummyOverrides(None)
+        self._registerOverrides(overrides)
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = os.path.join(here, resource_name)
+        result = provider.get_resource_filename(None, resource_name)
+        self.assertEqual(result, expected)
+
+    def test_get_resource_string_override_returns_None(self):
+        overrides = DummyOverrides(None)
+        self._registerOverrides(overrides)
+        import os
+        resource_name = 'test_resource.py'
+        import repoze.bfg.tests
+        provider = self._makeOne(repoze.bfg.tests)
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = os.path.join(here, resource_name)
+        result = provider.get_resource_filename(None, resource_name)
+        self.assertEqual(result, expected)
+
+    def test_get_resource_filename_override_returns_value(self):
+        overrides = DummyOverrides('value')
+        import repoze.bfg.tests
+        self._registerOverrides(overrides)
+        provider = self._makeOne(repoze.bfg.tests)
+        result = provider.get_resource_filename(None, 'test_resource.py')
+        self.assertEqual(result, 'value')
+
+    def test_get_resource_stream_override_returns_value(self):
+        overrides = DummyOverrides('value')
+        import repoze.bfg.tests
+        self._registerOverrides(overrides)
+        provider = self._makeOne(repoze.bfg.tests)
+        result = provider.get_resource_stream(None, 'test_resource.py')
+        self.assertEqual(result, 'value')
+
+    def test_get_resource_string_override_returns_value(self):
+        overrides = DummyOverrides('value')
+        import repoze.bfg.tests
+        self._registerOverrides(overrides)
+        provider = self._makeOne(repoze.bfg.tests)
+        result = provider.get_resource_string(None, 'test_resource.py')
+        self.assertEqual(result, 'value')
+
+class TestPackageOverrides(unittest.TestCase):
+    def _getTargetClass(self):
+        from repoze.bfg.resource import PackageOverrides
+        return PackageOverrides
+
+    def _makeOne(self, package):
+        klass = self._getTargetClass()
+        return klass(package)
+
+    def test_insert_directory(self):
+        from repoze.bfg.resource import DirectoryOverride
+        po = self._makeOne('package')
+        po.overrides= [None]
+        po.insert('foo/', 'package', 'bar/')
+        self.assertEqual(len(po.overrides), 2)
+        override = po.overrides[0]
+        self.assertEqual(override.__class__, DirectoryOverride)
+
+    def test_insert_file(self):
+        from repoze.bfg.resource import FileOverride
+        po = self._makeOne('package')
+        po.overrides= [None]
+        po.insert('foo.pt', 'package', 'bar.pt')
+        self.assertEqual(len(po.overrides), 2)
+        override = po.overrides[0]
+        self.assertEqual(override.__class__, FileOverride)
+
+    def test_search_path(self):
+        overrides = [ DummyOverride(None), DummyOverride(('package', 'name'))]
+        po = self._makeOne('package')
+        po.overrides= overrides
+        self.assertEqual(list(po.search_path('whatever')),
+                         [('package', 'name')])
+
+    def test_get_filename(self):
+        import os
+        overrides = [ DummyOverride(None), DummyOverride(
+            ('repoze.bfg.tests', 'test_resource.py'))]
+        po = self._makeOne('package')
+        po.overrides= overrides
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = os.path.join(here, 'test_resource.py')
+        self.assertEqual(po.get_filename('whatever'), expected)
+        
+    def test_get_stream(self):
+        import os
+        overrides = [ DummyOverride(None), DummyOverride(
+            ('repoze.bfg.tests', 'test_resource.py'))]
+        po = self._makeOne('package')
+        po.overrides= overrides
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = open(os.path.join(here, 'test_resource.py')).read()
+        self.assertEqual(po.get_stream('whatever').read(), expected)
+        
+    def test_get_string(self):
+        import os
+        overrides = [ DummyOverride(None), DummyOverride(
+            ('repoze.bfg.tests', 'test_resource.py'))]
+        po = self._makeOne('package')
+        po.overrides= overrides
+        here = os.path.dirname(os.path.abspath(__file__))
+        expected = open(os.path.join(here, 'test_resource.py')).read()
+        self.assertEqual(po.get_string('whatever'), expected)
+        
+
+class TestDirectoryOverride(unittest.TestCase):
+    def _getTargetClass(self):
+        from repoze.bfg.resource import DirectoryOverride
+        return DirectoryOverride
+
+    def _makeOne(self, path, package, prefix):
+        klass = self._getTargetClass()
+        return klass(path, package, prefix)
+
+    def test_it_match(self):
+        o = self._makeOne('foo/', 'package', 'bar/')
+        result = o('foo/something.pt')
+        self.assertEqual(result, ('package', 'bar/something.pt'))
+        
+    def test_it_no_match(self):
+        o = self._makeOne('foo/', 'package', 'bar/')
+        result = o('baz/notfound.pt')
+        self.assertEqual(result, None)
+        
+
+class TestFileOverride(unittest.TestCase):
+    def _getTargetClass(self):
+        from repoze.bfg.resource import FileOverride
+        return FileOverride
+
+    def _makeOne(self, path, package, prefix):
+        klass = self._getTargetClass()
+        return klass(path, package, prefix)
+
+    def test_it_match(self):
+        o = self._makeOne('foo.pt', 'package', 'bar.pt')
+        result = o('foo.pt')
+        self.assertEqual(result, ('package', 'bar.pt'))
+        
+    def test_it_no_match(self):
+        o = self._makeOne('foo.pt', 'package', 'bar.pt')
+        result = o('notfound.pt')
+        self.assertEqual(result, None)
+        
+    
+
+class DummyOverride:
+    def __init__(self, result):
+        self.result = result
+
+    def __call__(self, resource_name):
+        return self.result
+    
+
+class DummyOverrides:
+    def __init__(self, result):
+        self.result = result
+
+    def get_filename(self, resource_name):
+        return self.result
+
+    get_stream = get_string = get_filename
+    
diff --git a/repoze/bfg/tests/test_templating.py b/repoze/bfg/tests/test_templating.py
index 57c6d0866..3ae0483d9 100644
--- a/repoze/bfg/tests/test_templating.py
+++ b/repoze/bfg/tests/test_templating.py
@@ -54,7 +54,6 @@ class TestRendererFromCache(unittest.TestCase):
 
     def test_relpath_alreadyregistered(self):
         from repoze.bfg.interfaces import ITemplateRenderer
-        import os
         from repoze.bfg.tests import test_templating
         module_name = test_templating.__name__
         relpath = 'test_templating.py'
@@ -65,7 +64,7 @@ class TestRendererFromCache(unittest.TestCase):
         self.failUnless(result is renderer)
 
     def test_relpath_notyetregistered(self):
-        from repoze.bfg.interfaces import ITemplateRenderer
+        from repoze.bfg import resource
         import os
         from repoze.bfg.tests import test_templating
         module_name = test_templating.__name__
diff --git a/repoze/bfg/tests/test_zcml.py b/repoze/bfg/tests/test_zcml.py
index 1a0ee3c3f..875628f5f 100644
--- a/repoze/bfg/tests/test_zcml.py
+++ b/repoze/bfg/tests/test_zcml.py
@@ -804,8 +804,6 @@ class TestRouteDirective(unittest.TestCase):
         self.assertEqual(route_args, ('name', 'path', None,))
 
     def test_without_view(self):
-        from zope.component import getUtility
-        from repoze.bfg.interfaces import IRequestFactories
         from repoze.bfg.zcml import connect_route
         
         context = DummyContext()
@@ -827,8 +825,6 @@ class TestRouteDirective(unittest.TestCase):
         self.assertEqual(route_args, ('name','path', None))
 
     def test_with_request_type(self):
-        from zope.component import getUtility
-        from repoze.bfg.interfaces import IRequestFactories
         from repoze.bfg.zcml import connect_route
         
         context = DummyContext()
@@ -849,6 +845,94 @@ class TestRouteDirective(unittest.TestCase):
         self.assertEqual(route_discriminator[3], 'GET')
         self.assertEqual(route_args, ('name','path', None))
 
+class TestResourceDirective(unittest.TestCase):
+    def setUp(self):
+        cleanUp()
+
+    def tearDown(self):
+        cleanUp()
+
+    def _callFUT(self, *arg, **kw):
+        from repoze.bfg.zcml import resource
+        return resource(*arg, **kw)
+
+    def test_samename(self):
+        from zope.configuration.exceptions import ConfigurationError
+        context = DummyContext()
+        self.assertRaises(ConfigurationError, self._callFUT, context, 'a', 'a')
+
+    def test_override_directory_with_file(self):
+        from zope.configuration.exceptions import ConfigurationError
+        context = DummyContext()
+        self.assertRaises(ConfigurationError, self._callFUT, context, 'a/', 'a')
+
+    def test_override_file_with_directory(self):
+        from zope.configuration.exceptions import ConfigurationError
+        context = DummyContext()
+        self.assertRaises(ConfigurationError, self._callFUT, context, 'a', 'a/')
+
+    def test_no_colons(self):
+        from repoze.bfg.zcml import _override
+        context = DummyContext()
+        self._callFUT(context, 'a', 'b')
+        actions = context.actions
+        self.assertEqual(len(actions), 1)
+        action = actions[0]
+        self.assertEqual(action['callable'], _override)
+        self.assertEqual(action['discriminator'], None)
+        self.assertEqual(action['args'],
+                         ('IDummy', '', 'IDummy', ''))
+
+    def test_with_colons(self):
+        from repoze.bfg.zcml import _override
+        context = DummyContext()
+        self._callFUT(context, 'a:foo.pt', 'b:foo.pt')
+        actions = context.actions
+        self.assertEqual(len(actions), 1)
+        action = actions[0]
+        self.assertEqual(action['callable'], _override)
+        self.assertEqual(action['discriminator'], None)
+        self.assertEqual(action['args'],
+                         ('IDummy', 'foo.pt', 'IDummy', 'foo.pt'))
+
+class Test_OverrideFunction(unittest.TestCase):
+    def setUp(self):
+        cleanUp()
+
+    def tearDown(self):
+        cleanUp()
+
+    def _callFUT(self, *arg, **kw):
+        from repoze.bfg.zcml import _override
+        return _override(*arg, **kw)
+
+    def _registerOverrides(self, overrides, package_name):
+        from repoze.bfg.interfaces import IPackageOverrides
+        from zope.component import getSiteManager
+        sm = getSiteManager()
+        sm.registerUtility(overrides, IPackageOverrides, name=package_name)
+
+    def test_overrides_not_yet_registered(self):
+        from repoze.bfg.resource import OverrideProvider
+        from zope.component import queryUtility
+        from repoze.bfg.interfaces import IPackageOverrides
+        resources = DummyPackageResources()
+        self._callFUT('package', 'path', 'opackage', 'oprefix',
+                      PackageOverrides=DummyOverrides, pkg_resources=resources)
+        overrides = queryUtility(IPackageOverrides, name='package')
+        self.assertEqual(overrides.package, 'package')
+        self.assertEqual(overrides.inserted, [('path', 'opackage', 'oprefix')])
+        self.assertEqual(len(resources.registered), 1)
+        resource = resources.registered[0]
+        self.assertEqual(resource[0], type(None))
+        self.assertEqual(resource[1], OverrideProvider)
+
+    def test_overrides_already_registered(self):
+        overrides = DummyOverrides('package')
+        self._registerOverrides(overrides, 'package')
+        self._callFUT('package', 'path', 'opackage', 'oprefix')
+        self.assertEqual(overrides.inserted, [('path', 'opackage', 'oprefix')])
+
 class TestZCMLConfigure(unittest.TestCase):
     i = 0
     def _callFUT(self, path, package):
@@ -1244,3 +1328,18 @@ class DummyRequest:
     def get_response(self, app):
         return app
     
+class DummyOverrides:
+    def __init__(self, package):
+        self.package = package
+        self.inserted = []
+
+    def insert(self, path, package, prefix):
+        self.inserted.append((path, package, prefix))
+        
+class DummyPackageResources:
+    def __init__(self):
+        self.registered  = []
+
+    def register_loader_type(self, typ, provider):
+        self.registered.append((typ, provider))
+        
diff --git a/repoze/bfg/zcml.py b/repoze/bfg/zcml.py
index 786301c45..38db4ead7 100644
--- a/repoze/bfg/zcml.py
+++ b/repoze/bfg/zcml.py
@@ -1,5 +1,6 @@
 import inspect
 import types
+import pkg_resources
 
 from zope.configuration import xmlconfig
 
@@ -27,6 +28,10 @@ from repoze.bfg.interfaces import IView
 from repoze.bfg.interfaces import IUnauthorizedAppFactory
 from repoze.bfg.interfaces import ILogger
 from repoze.bfg.interfaces import IRequestFactories
+from repoze.bfg.interfaces import IPackageOverrides
+
+from repoze.bfg.resource import OverrideProvider
+from repoze.bfg.resource import PackageOverrides
 
 from repoze.bfg.request import DEFAULT_REQUEST_FACTORIES
 from repoze.bfg.request import named_request_factories
@@ -155,6 +160,69 @@ def scan(_context, package, martian=martian):
     martian.grok_dotted_name(package.__name__, grokker=module_grokker,
                              context=_context, exclude_filter=exclude)
 
+class IResourceDirective(Interface):
+    """
+    Directive for specifying that one package may override resources from
+    another package.
+    """
+    to_override = TextLine(
+        title=u"Override spec",
+        description=u'The spec of the resource to override.',
+        required=True)
+    override_with = TextLine(
+        title=u"With spec",
+        description=u"The spec of the resource providing the override.",
+        required=True)
+
+def _override(package, path, override_package, override_prefix,
+              PackageOverrides=PackageOverrides, pkg_resources=pkg_resources):
+    # PackageOverrides and pkg_resources kw args for tests
+    sm = getSiteManager()
+    override = queryUtility(IPackageOverrides, name=package)
+    if override is None:
+        override = PackageOverrides(package)
+        sm.registerUtility(override, IPackageOverrides, name=package)
+        # register_loader_type will be called too many times if there
+        # is more than one overridden package; that's OK, as our
+        # mutation is idempotent
+        pkg_resources.register_loader_type(type(None), OverrideProvider)
+    override.insert(path, override_package, override_prefix)
+
+def resource(context, to_override, override_with):
+    if to_override == override_with:
+        raise ConfigurationError('You cannot override a resource with itself')
+
+    if to_override.endswith('/'):
+        if not override_with.endswith('/'):
+            raise ConfigurationError(
+                'A directory cannot be overridden with a file (put a slash '
+                'at the end of override_with if necessary)')
+
+    if override_with.endswith('/'):
+        if not to_override.endswith('/'):
+            raise ConfigurationError(
+                'A file cannot be overridden with a directory (put a slash '
+                'at the end of to_override if necessary)')
+
+    package = to_override
+    path = ''
+    if ':' in to_override:
+        package, path = to_override.split(':', 1)
+
+    override_package = override_with
+    override_prefix = ''
+    if ':' in override_with:
+        override_package, override_prefix = override_with.split(':', 1)
+
+    package = context.resolve(package).__name__
+    override_package = context.resolve(package).__name__
+
+    context.action(
+        discriminator = None,
+        callable = _override,
+        args = (package, path, override_package, override_prefix),
+        )
+
 class IRouteDirective(Interface):
     """ The interface for the ``route`` ZCML directive
     """