Use `nose.__loader__` to load 'usage.txt', if available.

Previously we only used `nose.__loader__` if we thought
that the loader was zipimporter. Additionally, we use
`nose.__file__` to build the path to 'usage.txt' as
suggested by PEP-302.

1 files changed, 14 insertions, 7 deletions

diff --git a/nose/core.py b/nose/core.py
index b78f232..e57a88f 100644
--- a/nose/core.py
+++ b/nose/core.py
@@ -237,14 +237,21 @@ class TestProgram(unittest.TestProgram):
 
     def usage(cls):
         import nose
-        if hasattr(nose, '__loader__'):
+        try:
             ld = nose.__loader__
-            if hasattr(ld, 'zipfile'):
-                # nose was imported from a zipfile
-                return ld.get_data(
-                        os.path.join(ld.prefix, 'nose', 'usage.txt'))
-        return open(os.path.join(
-                os.path.dirname(__file__), 'usage.txt'), 'r').read()
+            text = ld.get_data(os.path.join(
+                os.path.dirname(__file__), 'usage.txt'))
+        except AttributeError:
+            f = open(os.path.join(
+                os.path.dirname(__file__), 'usage.txt'), 'r')
+            try:
+                text = f.read()
+            finally:
+                f.close()
+        # Ensure that we return str, not bytes.
+        if not isinstance(text, str):
+            text = text.decode('utf-8')
+        return text
     usage = classmethod(usage)
 
 # backwards compatibility