don't consider setuptools plugins if it is not installed.

--HG--
branch : trunk

py/impl/test/pluginmanager.py

@@ -78,7 +78,10 @@ class PluginManager(object):
             self.import_plugin(spec)
 
     def consider_setuptools_entrypoints(self):
-        from pkg_resources import iter_entry_points
+        try:
+            from pkg_resources import iter_entry_points
+        except ImportError:
+            return # XXX issue a warning 
         for ep in iter_entry_points('pytest11'):
             if ep.name in self._name2plugin:
                 continue

testing/pytest/test_pluginmanager.py

@@ -60,6 +60,13 @@ class TestBootstrapping:
         plugin = pluginmanager.getplugin("mytestplugin")
         assert plugin.x == 42
 
+    def test_consider_setuptools_not_installed(self, monkeypatch):
+        monkeypatch.setitem(py.std.sys.modules, 'pkg_resources', 
+            py.std.types.ModuleType("pkg_resources"))
+        pluginmanager = PluginManager()
+        pluginmanager.consider_setuptools_entrypoints()
+        # ok, we did not explode
+
     def test_pluginmanager_ENV_startup(self, testdir, monkeypatch):
         x500 = testdir.makepyfile(pytest_x500="#")
         p = testdir.makepyfile("""