Catching an unhandled SystemError occurring in some tests. RE:#72

src/natcap/invest/utils.py

@@ -174,8 +174,16 @@ def log_to_file(logfile, exclude_threads=None, logging_level=logging.NOTSET,
 
     Returns:
         ``None``"""
+    try:
         if os.path.exists(logfile):
             LOGGER.warn('Logfile %s exists and will be overwritten', logfile)
+    except SystemError:
+        # This started happening in Windows tests:
+        #  SystemError: <built-in function stat> returned NULL without
+        #  setting an error
+        # Looking at https://bugs.python.org/issue28040#msg276223, this might
+        # be a low-level python error.
+        pass
 
     handler = logging.FileHandler(logfile, 'w', encoding='UTF-8')
     formatter = logging.Formatter(log_fmt, date_fmt)

ui_tests/test_cli_gui.py

@@ -16,7 +16,6 @@ class CLIGUITests(unittest.TestCase):
     def test_run_model(self):
         """CLI-GUI: Run a model GUI through the cli."""
         from natcap.invest import cli
-        from natcap.invest import delineateit
         parameter_set_path = os.path.join(
             os.path.dirname(__file__), '..', 'data', 'invest-test-data',
             'fisheries', 'spiny_lobster_belize.invs.json')