[testlib] fix bug in traceback formatting: handle cases where we source code is not available

1 files changed, 4 insertions, 1 deletions

diff --git a/testlib.py b/testlib.py
index 15d2df3..55c809b 100644
--- a/testlib.py
+++ b/testlib.py
@@ -392,7 +392,10 @@ class SkipAwareTestResult(unittest._TextTestResult):
             if not (0 < index <= nb_frames_skipped):
                 continue
             filename = osp.abspath(filename)
-            source = ''.join(ctx)
+            if ctx is None: # pyc files or C extensions for instance
+                source = '<no source available>'
+            else:
+                source = ''.join(ctx)
             if colorize:
                 filename = textutils.colorize_ansi(filename, 'magenta')
                 source = colorize_source(source)