Update testing for exit code changes

The testing needs to be updated now that `example.main()` only returns a
`None` and error exits are done by directly calling `sys.exit()`.

tests/test_example.py

@@ -79,18 +79,26 @@ def test_log_levels(level):
             assert (
                 logging.root.hasHandlers() is False
             ), "root logger should not have handlers yet"
-            return_code = example.example.main()
+            return_code = None
+            try:
+                example.example.main()
+            except SystemExit as sys_exit:
+                return_code = sys_exit.code
+            assert return_code is None, "main() should return success"
             assert (
                 logging.root.hasHandlers() is True
             ), "root logger should now have a handler"
-            assert return_code == 0, "main() should return success (0)"
 
 
 def test_bad_log_level():
     """Validate bad log-level argument returns error."""
     with patch.object(sys, "argv", ["bogus", "--log-level=emergency", "1", "1"]):
-        return_code = example.example.main()
-        assert return_code == 1, "main() should return failure"
+        return_code = None
+        try:
+            example.example.main()
+        except SystemExit as sys_exit:
+            return_code = sys_exit.code
+        assert return_code == 1, "main() should exit with error"
 
 
 @pytest.mark.parametrize("dividend, divisor, quotient", div_params)
@@ -124,5 +132,9 @@ def test_zero_division():
 def test_zero_divisor_argument():
     """Verify that a divisor of zero is handled as expected."""
     with patch.object(sys, "argv", ["bogus", "1", "0"]):
-        return_code = example.example.main()
+        return_code = None
+        try:
+            example.example.main()
+        except SystemExit as sys_exit:
+            return_code = sys_exit.code
         assert return_code == 1, "main() should exit with error"