If you called sys.exit() with no argument, coverage.py got tangled. Thanks, Brodie Rao.

3 files changed, 25 insertions, 2 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 2e6cdf22..27b1f72b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -8,6 +8,9 @@ Version 3.4
 
 - The XML report is now sorted by package name, fixing `issue 88`_.
 
+- Programs that exited with ``sys.exit()`` with no argument weren't handled
+  properly, producing a coverage.py stack trace.  That is now fixed.
+
 .. _issue 88: http://bitbucket.org/ned/coveragepy/issue/88/xml-report-lists-packages-in-random-order
 
 
diff --git a/coverage/cmdline.py b/coverage/cmdline.py
index f56cc4cb..e5d6bb84 100644
--- a/coverage/cmdline.py
+++ b/coverage/cmdline.py
@@ -652,7 +652,10 @@ def main(argv=None):
         print(err)
         status = ERR
     except SystemExit:
-        # The user called `sys.exit()`.  Exit with their status code.
+        # The user called `sys.exit()`.  Exit with their argument, if any.
         _, err, _ = sys.exc_info()
-        status = err.args[0]
+        if err.args:
+            status = err.args[0]
+        else:
+            status = None
     return status
diff --git a/test/test_process.py b/test/test_process.py
index 169bd7bf..bb255fe9 100644
--- a/test/test_process.py
+++ b/test/test_process.py
@@ -204,6 +204,23 @@ class ProcessTest(CoverageTest):
         self.assertEqual(status, status2)
         self.assertEqual(status, 17)
 
+    def test_code_exits_no_arg(self):
+        self.make_file("exit_none.py", """\
+            import sys
+            def f1():
+                print("about to exit quietly..")
+                sys.exit()
+
+            f1()
+            """)
+        status, out = self.run_command_status("coverage run exit_none.py", 0)
+        status2, out2 = self.run_command_status("python exit_none.py", 0)
+        self.assertMultiLineEqual(out, out2)
+        self.assertMultiLineEqual(out, "about to exit quietly..\n")
+        self.assertEqual(status, status2)
+        self.assertEqual(status, 0)
+
+
     if hasattr(os, 'fork'):
         def test_fork(self):
             self.make_file("fork.py", """\