Find Docker format without "repositories" #32

This adds a test to validate that we do not need the legcacy Docker v1
"repositories" file to be present to recognize a Docker image layout.

Signed-off-by: Philippe Ombredanne <[email protected]>

Author: pombredanne

tests/data/image/mini-image_from_scratch-2.0.tar

@@ -140,3 +140,8 @@ def test_Image_find_format(self):
         test_arch = self.get_test_loc('image/she-image_from_scratch-1.0.tar')
         test_dir = self.extract_test_tar(test_arch)
         assert Image.find_format(test_dir) == 'docker'
+
+    def test_Image_find_format_finds_Docker_images_without_repositories(self):
+        test_arch = self.get_test_loc('image/mini-image_from_scratch-2.0.tar')
+        test_dir = self.extract_test_tar(test_arch)
+        assert Image.find_format(test_dir) == 'docker'