From 28277a6b19b1574b908843d15df8f0013d16c6bd Mon Sep 17 00:00:00 2001
From: Ivan Danov <idanov@users.noreply.github.com>
Date: Mon, 15 Apr 2024 12:09:50 +0100
Subject: [PATCH] Add a test for transcoding loops of 1 or more nodes (#3810)

Signed-off-by: Ivan Danov <idanov@users.noreply.github.com>
---
 kedro/pipeline/pipeline.py                    |  3 ++-
 .../test_pipeline_with_transcoding.py         | 24 ++++++++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/kedro/pipeline/pipeline.py b/kedro/pipeline/pipeline.py
index 29d647b387..5a0d63b4cf 100644
--- a/kedro/pipeline/pipeline.py
+++ b/kedro/pipeline/pipeline.py
@@ -171,7 +171,8 @@ def __init__(
         try:
             self._toposorter.prepare()
         except CycleError as exc:
-            message = f"Circular dependencies exist among these items: {exc.args[1]}"
+            loop = list(set(exc.args[1]))
+            message = f"Circular dependencies exist among the following {len(loop)} item(s): {loop}"
             raise CircularDependencyError(message) from exc
 
         self._toposorted_nodes: list[Node] = []
diff --git a/tests/pipeline/test_pipeline_with_transcoding.py b/tests/pipeline/test_pipeline_with_transcoding.py
index c8dc87441a..7e4ad04056 100644
--- a/tests/pipeline/test_pipeline_with_transcoding.py
+++ b/tests/pipeline/test_pipeline_with_transcoding.py
@@ -5,7 +5,11 @@
 import kedro
 from kedro.pipeline import node
 from kedro.pipeline.modular_pipeline import pipeline as modular_pipeline
-from kedro.pipeline.pipeline import OutputNotUniqueError, _strip_transcoding
+from kedro.pipeline.pipeline import (
+    CircularDependencyError,
+    OutputNotUniqueError,
+    _strip_transcoding,
+)
 
 
 # Different dummy func based on the number of arguments
@@ -177,6 +181,24 @@ def test_duplicates_in_transcoded_outputs(self):
                 ]
             )
 
+    def test_transcoding_loop(self):
+        with pytest.raises(CircularDependencyError, match="node1"):
+            modular_pipeline(
+                [
+                    node(identity, "A@pandas", "B@pandas", name="node1"),
+                    node(identity, "B@spark", "C@spark", name="node2"),
+                    node(identity, "C@spark", "A@spark", name="node3"),
+                ]
+            )
+
+    def test_transcoding_self_reference(self):
+        with pytest.raises(CircularDependencyError, match="node1"):
+            modular_pipeline(
+                [
+                    node(identity, "A@pandas", "A@spark", name="node1"),
+                ]
+            )
+
 
 class TestComplexPipelineWithTranscoding:
     """