Fix undefined rubygems version

Traceback (most recent call last):
  ...
    recipe.install()
  File "rubygemsrecipe/rubygems.py", line 347, in install
    gem_executable):
  File "rubygemsrecipe/rubygems.py", line 300, in get_dependency_list
    if self.version[0] < '3':
TypeError: 'NoneType' object has no attribute '__getitem__'

The test that was added in 60b10788 is adapted due to the call to subprocess.checkout .

rubygems.py

@@ -293,6 +293,11 @@ class Recipe(object):
         gem_executable = glob.glob(gem_executable + '*')
 
         if gem_executable:
+            if not self.version:
+                self.version = self.run([
+                    gem_executable[0],
+                    '--version',
+                ])
             return gem_executable[0]
 
     def get_dependency_list(self, gem_dict, gem_executable):

tests/test_rubygems.py

@@ -17,6 +17,8 @@ import zc.buildout
 
 import rubygems
 
+RUBYGEMS_DEFAULT_VERSION = '2.0.0'
+
 
 def touch(path):
     with path.open('w') as f:
@@ -24,7 +26,7 @@ def touch(path):
 
 
 class fixture(object):
-    def __init__(self, options=None, version='2.0.0'):
+    def __init__(self, options=None, version=RUBYGEMS_DEFAULT_VERSION):
         self.options = options or {}
         self.version = version
 
@@ -61,7 +63,9 @@ class fixture(object):
             ('download', 'rubygems.Download'),
         ))
         self.patches['urlopen'].return_value = BytesIO(
-            b'https://rubygems.org/rubygems/rubygems-2.0.0.zip'
+            bytes(('https://rubygems.org/rubygems/rubygems-%s.zip'
+                   % RUBYGEMS_DEFAULT_VERSION
+                  ).encode('utf-8'))
         )
 
         self.makedirs((
@@ -108,8 +112,9 @@ class RubyGemsTestCase(unittest.TestCase):
 
         args = patches['download'].mock_calls[0][1]
         self.assertEqual(args[2], {
-            'url': 'https://rubygems.org/rubygems/rubygems-2.0.0.zip',
-            'destination': str(path / 'rubygems-2.0.0'),
+            'url': 'https://rubygems.org/rubygems/rubygems-%s.zip'
+                    % RUBYGEMS_DEFAULT_VERSION,
+            'destination': str(path / ('rubygems-' + RUBYGEMS_DEFAULT_VERSION)),
         })
 
         expected_install_arg_list_list.insert(0, [
@@ -193,13 +198,14 @@ class RubyGemsDefaultTestCase(RubyGemsTestCase):
 
     @fixture({'recipe': {
         'gems': 'sass',
-        'url': 'https://rubygems.org/rubygems/rubygems-2.0.0.zip',
+        'url': 'https://rubygems.org/rubygems/rubygems-%s.zip'
+                % RUBYGEMS_DEFAULT_VERSION,
     }})
     def test_version_from_url(self, path, patches, buildout, name, options, version):
         recipe = rubygems.Recipe(buildout, name, options)
         recipe.install()
 
-    @fixture({'recipe': {'gems': 'sass'}, 'version': '2.0.0'})
+    @fixture({'recipe': {'gems': 'sass'}, 'version': RUBYGEMS_DEFAULT_VERSION})
     def test_version(self, path, patches, buildout, name, options, version):
         recipe = rubygems.Recipe(buildout, name, options)
         recipe.install()
@@ -236,7 +242,7 @@ class RubyGemsDefaultTestCase(RubyGemsTestCase):
         touch(path / 'rubygems/bin/gem')
         recipe.install()
 
-        args = patches['check_output'].mock_calls[0][1]
+        args = patches['check_output'].mock_calls[1][1]
         for arg in args[0]:
             matched = re.search('^--version.*$', arg)
             if matched:
@@ -303,9 +309,13 @@ class RubyGemsDeploymentTestCase(RubyGemsTestCase):
             path, patches, expected_install_arg_list_list)
 
     @deployment_fixture({'recipe': {'gems': 'hashie==0.3.1'}})
+    @mock.patch('rubygems.Recipe.get_gem_executable')
     def test_already_installed_rubygems(
-            self, path, patches, buildout, name, options, version):
+            self, path, patches, buildout, name, options, version, get_gem_exe):
         touch(path / 'rubygems/bin/gem')
+        def mocked_get_gem_exe(_):
+            self.version = RUBYGEMS_DEFAULT_VERSION
+        get_gem_exe.side_effect = mocked_get_gem_exe
         self.deployment_install_test(
             buildout, name, path, patches, options, version)