import: intercept and rephrase OutputNotFound message

dvc/exceptions.py

@@ -59,10 +59,12 @@ class OutputNotFoundError(DvcException):
         output (unicode): path to the file/directory.
     """
 
-    def __init__(self, output):
+    def __init__(self, output, repo=None):
+        self.output = output
+        self.repo = repo
         super(OutputNotFoundError, self).__init__(
             "unable to find DVC-file with output '{path}'".format(
-                path=relpath(output)
+                path=relpath(self.output)
             )
         )
 
@@ -338,3 +340,12 @@ def __init__(self, url, cause=None):
             ),
             cause=cause,
         )
+
+
+class NoOutputInExternalRepoError(DvcException):
+    def __init__(self, path, external_repo_path, external_repo_url):
+        super(NoOutputInExternalRepoError, self).__init__(
+            "Output '{}' not found in target repository '{}'".format(
+                relpath(path, external_repo_path), external_repo_url
+            )
+        )

dvc/external_repo.py

@@ -9,6 +9,8 @@
 
 from dvc.config import NoRemoteError
 from dvc.exceptions import RemoteNotSpecifiedInExternalRepoError
+from dvc.exceptions import NoOutputInExternalRepoError
+from dvc.exceptions import OutputNotFoundError
 from dvc.utils.fs import remove
 
 
@@ -25,6 +27,10 @@ def external_repo(url=None, rev=None, rev_lock=None, cache_dir=None):
         yield repo
     except NoRemoteError as exc:
         raise RemoteNotSpecifiedInExternalRepoError(url, cause=exc)
+    except OutputNotFoundError as exc:
+        if exc.repo is repo:
+            raise NoOutputInExternalRepoError(exc.output, repo.root_dir, url)
+        raise
     repo.close()
 
 

dvc/repo/__init__.py

@@ -435,7 +435,7 @@ def func(out):
 
         matched = list(filter(func, outs))
         if not matched:
-            raise OutputNotFoundError(path)
+            raise OutputNotFoundError(path, self)
 
         return matched
 

tests/func/test_import.py

@@ -8,7 +8,7 @@
 from mock import patch
 
 from dvc.config import Config
-from dvc.exceptions import DownloadError
+from dvc.exceptions import DownloadError, NoOutputInExternalRepoError
 from dvc.stage import Stage
 from dvc.system import System
 from dvc.utils import makedirs
@@ -154,3 +154,8 @@ def test_pull_non_workspace(git, dvc_repo, erepo):
     os.remove(stage.outs[0].cache_path)
     dvc_repo.fetch(all_tags=True)
     assert os.path.exists(stage.outs[0].cache_path)
+
+
+def test_import_non_existing(dvc_repo, erepo):
+    with pytest.raises(NoOutputInExternalRepoError):
+        dvc_repo.imp(erepo.root_dir, "invalid_output")