add unit test coverage for pull-sources

charmtools/pullsource.py

@@ -104,8 +104,8 @@ def download_item(args):
         # Download the item
         fetcher = fetchers.get_fetcher(args.item)
         download_dir = fetcher.fetch(tempdir)
-    except fetchers.FetchError:
-        print("Can't find source for {}".format(args.item))
+    except fetchers.FetchError as e:
+        print("Can't find source for {} ({})".format(args.item, e))
         return 1
 
     # Copy download dir to final destination dir

tests/test_pullsource.py

@@ -0,0 +1,44 @@
+import os
+import re
+from types import SimpleNamespace
+import unittest
+import unittest.mock as mock
+from tempfile import NamedTemporaryFile, TemporaryDirectory
+
+from charmtools import pullsource
+
+
+class TestPullSource(unittest.TestCase):
+    @mock.patch('builtins.print')
+    def test__download_item_cs_prefix(self, mock_print):
+        """Don't support downloads from any cs: prefix."""
+        args = SimpleNamespace(item="cs:fake-charm")
+        assert pullsource.download_item(args) == 1
+        mock_print.assert_called_once_with("Cannot download source for charm cs:fake-charm")
+
+    @mock.patch('builtins.print')
+    def test__download_fake_layer_prefix(self, mock_print):
+        """Confirm supports downloads from layers: prefix."""
+        with TemporaryDirectory() as tmpdir:
+            args = SimpleNamespace(item="layer:fake-layer", dir=tmpdir)
+            assert pullsource.download_item(args) == 1
+        mock_print.assert_called_once_with("Can't find source for layer:fake-layer (No fetcher for url: layer:fake-layer)")
+
+    @mock.patch('builtins.print')
+    @mock.patch.object(pullsource, 'fetchers')
+    def test__download_layer_basic(self, mock_fetchers, mock_print):
+        """Confirm supports downloads from layers: prefix."""
+        fetcher = mock_fetchers.get_fetcher.return_value
+        fetcher.revision = "abcdefghijklmnop"
+        with TemporaryDirectory() as tmpdir:
+            mkdir = fetcher.fetch.return_value = os.path.join(tmpdir, "source")
+            os.mkdir(mkdir)
+            with NamedTemporaryFile(dir=fetcher.fetch.return_value):
+                args = SimpleNamespace(item="layer:fake-layer", dir=tmpdir)
+                assert pullsource.download_item(args) is None
+        mock_print.assert_called_once()
+        args, _ = mock_print.call_args
+        rev_match = re.search(r"rev: ([a-z0-9]+)", args[0])
+        assert rev_match, f"'{args[0]}', didn't contain a match for rev: ([a-z0-9]+)"
+        assert rev_match.groups()[0] == fetcher.revision
+