Allow unicode strings in parser.add_argument()

This fixes issue360 by also converting unicode strings to the argparse
syntax instead of just native strings.

CHANGELOG

@@ -1,7 +1,8 @@
 Changes between 2.4.0 and X
 -----------------------------------
 
-
+- fix issue360: When using parser.addoption() unicode arguments to the
+  "type" keyword should also be converted to the respective types.
 
 Changes between 2.3.5 and 2.4
 -----------------------------------

_pytest/config.py

@@ -238,7 +238,7 @@ class Argument:
             pass
         else:
             # this might raise a keyerror as well, don't want to catch that
-            if isinstance(typ, str):
+            if isinstance(typ, py.builtin._basestring):
                 if typ == 'choice':
                     if self.TYPE_WARN:
                         py.std.warnings.warn(

testing/test_config.py

@@ -113,6 +113,17 @@ class TestConfigAPI:
             assert config.getoption(x) == "this"
         pytest.raises(ValueError, "config.getoption('qweqwe')")
 
+    @pytest.mark.skipif('sys.version_info[:2] not in [(2, 6), (2, 7)]')
+    def test_config_getoption_unicode(self, testdir):
+        testdir.makeconftest("""
+            from __future__ import unicode_literals
+
+            def pytest_addoption(parser):
+                parser.addoption('--hello', type='string')
+        """)
+        config = testdir.parseconfig('--hello=this')
+        assert config.getoption('hello') == 'this'
+
     def test_config_getvalueorskip(self, testdir):
         config = testdir.parseconfig()
         pytest.raises(pytest.skip.Exception,