Add test for valid & invalid docker image names

repo2docker/__main__.py

@@ -5,7 +5,7 @@ import logging
 import docker
 from .app import Repo2Docker
 from . import __version__
-from .utils import validate_and_generate_port_mapping
+from .utils import validate_and_generate_port_mapping, is_valid_docker_image_name
 
 def validate_image_name(image_name):
     """

tests/test_args.py

@@ -76,4 +76,12 @@ def test_clean():
     # Don't clean by default when repo exists locally
     assert not make_r2d(['.']).cleanup_checkout
     # Don't clean when repo exists locally and we explicitly ask it to not clean
-    assert not make_r2d(['--no-clean', '.']).cleanup_checkout
+    assert not make_r2d(['--no-clean', '.']).cleanup_checkout
+
+
+def test_invalid_image_name():
+    """
+    Test validating image names
+    """
+    with pytest.raises(SystemExit):
+        make_r2d(['--image-name', '_invalid', '.'])