Add a zc.recipe.egg test case.

src/zc/buildout/allow-unknown-extras.txt

+======================
+ Allow Unknown Extras
+======================
+
+Sometimes we need to allow unknown extras.
+
+The ``allow-unknown-extras`` option lets us do that in a buildout
+configuration, just as we can directly calling ``easy_install``
+works exactly like the one provided in ``easy_install``.
+
+Let's create a develop egg that requires a bogus extra.
+
+    >>> mkdir(sample_buildout, 'allowdemo')
+    >>> write(sample_buildout, 'allowdemo', 'dependencydemo.py',
+    ...       'import eggrecipekss.core')
+    >>> write(sample_buildout, 'allowdemo', 'setup.py',
+    ... '''from setuptools import setup; setup(
+    ...     name='allowdemo', py_modules=['dependencydemo'],
+    ...     zip_safe=True, version='1')
+    ... ''')
+
+Now let's configure the buildout to use the develop egg with a bogus extra.
+
+    >>> write(sample_buildout, 'buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... develop = allowdemo
+    ... parts = eggs
+    ...
+    ... [eggs]
+    ... recipe = zc.recipe.egg:eggs
+    ... eggs = allowdemo[bad_extra]
+    ... ''')
+
+Now we can run the buildout and see that it fails:
+
+    >>> print_(system(buildout), end='') # doctest: +ELLIPSIS
+    Develop: '/sample-buildout/allowdemo'
+    Installing eggs...
+    ...
+    While:
+      Installing eggs.
+    Error: Couldn't find the required extras. Add 'allow-unknown-extras=true' to the [buildout] configuration if this is acceptable.
+
+If we flip the option on, the buildout succeeds
+
+    >>> write(sample_buildout, 'buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... develop = allowdemo
+    ... parts = eggs
+    ... allow-unknown-extras = true
+    ...
+    ... [eggs]
+    ... recipe = zc.recipe.egg:eggs
+    ... eggs = allowdemo[bad_extra]
+    ... ''')
+
+
+Now we can run the buildout and make sure all attempts to dist.plone.org fails::
+
+    >>> print_(system(buildout), end='') # doctest: +ELLIPSIS
+    Develop: '/sample-buildout/allowdemo'
+    Installing eggs...
+    allowdemo 1 does not provide the extra 'bad_extra'

src/zc/buildout/tests.py

@@ -3712,7 +3712,7 @@ def test_suite():
 
         doctest.DocFileSuite(
             'easy_install.txt', 'downloadcache.txt', 'dependencylinks.txt',
-            'allowhosts.txt',
+            'allowhosts.txt', 'allow-unknown-extras.txt',
             setUp=easy_install_SetUp,
             tearDown=zc.buildout.testing.buildoutTearDown,
             optionflags=doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS,

zc.recipe.egg_/src/zc/recipe/egg/egg.py

@@ -84,7 +84,7 @@ class Eggs(object):
             links=self.links,
             index=self.index,
             allow_hosts=self.allow_hosts,
-            allow_unknown_extras=bool_option(buildout['buildout'], 'allow-unknown-extras')
+            allow_unknown_extras=bool_option(buildout_section, 'allow-unknown-extras')
             )
 
         return orig_distributions, ws