improve error message for mismatched pipelines (#24834)

Co-authored-by: tvalentyn <tvalentyn@users.noreply.github.com>
apache · Jan 20, 2023 · 428ec97 · 428ec97
1 parent c1b840a
commit 428ec97
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/sdks/python/apache_beam/transforms/util.py b/sdks/python/apache_beam/transforms/util.py
@@ -234,7 +234,8 @@ def expand(self, pcolls):
     for pcoll in pcolls.values():
       self._check_pcollection(pcoll)
       if self.pipeline:
-        assert pcoll.pipeline == self.pipeline
+        assert pcoll.pipeline == self.pipeline, (
+            'All input PCollections must belong to the same pipeline.')
 
     tags = list(pcolls.keys())