handle missing env variable

py/desitransfer/spacewatch.py

@@ -134,7 +134,7 @@ def _options():
     prsr.add_argument('-o', '--overwrite', action='store_true',
                       help='Overwrite any existing files.')
     prsr.add_argument('-s', '--server', metavar='SERVER',
-                      default=os.environ['SPACEWATCH_SERVER'],
+                      default=os.getenv('SPACEWATCH_SERVER', 'SPACEWATCH_SERVER'),
                       help='Set the Spacwatch server name to SERVER (default "%(default)s").')
     prsr.add_argument('-t', '--test', action='store_true',
                       help='Do not actually download any files; implies --debug.')
@@ -158,7 +158,7 @@ def main():
         log = get_logger(DEBUG)
     else:
         log = get_logger()
-    if options.server is None:
+    if options.server == 'SPACEWATCH_SERVER':
         log.critical("Spacewatch server name is not set!")
         return 1
     spacewatch_root = f'https://{options.server}/allsky-all/images/cropped/'

py/desitransfer/test/test_spacewatch.py

@@ -36,9 +36,19 @@ def tearDown(self):
     def test_options(self):
         """Test command-line arguments.
         """
+        with patch.object(sys, 'argv', ['desi_spacewatch_transfer', '--debug', '/desi/external/spacewatch']):
+            with patch.dict('os.environ', {'SPACEWATCH_SERVER': 'www.example.com'}):
+                options = _options()
+        self.assertTrue(options.debug)
+        self.assertEqual(options.server, 'www.example.com')
+
+    def test_options_bad_env(self):
+        """Test command-line arguments with missing env variable.
+        """
         with patch.object(sys, 'argv', ['desi_spacewatch_transfer', '--debug', '/desi/external/spacewatch']):
             options = _options()
-            self.assertTrue(options.debug)
+        self.assertTrue(options.debug)
+        self.assertEqual(options.server, 'SPACEWATCH_SERVER')
 
     @patch('desitransfer.spacewatch.requests')
     def test_jpg_files(self, mock_requests):