We still need to raise error if components do not have at least one of the two methods implemented

Author: stellasia

src/neo4j_graphrag/experimental/pipeline/component.py

@@ -37,7 +37,11 @@ def __new__(
         # extract required inputs and outputs from the run method signature
         run_method = attrs.get("run")
         run_context_method = attrs.get("run_with_context")
-        run = run_context_method or run_method
+        run = run_context_method if run_context_method is not None else run_method
+        if run is None:
+            raise RuntimeError(
+                f"You must implement either `run` or `run_with_context` in Component '{name}'"
+            )
         sig = inspect.signature(run)
         attrs["component_inputs"] = {
             param.name: {

tests/unit/experimental/pipeline/test_component.py

@@ -16,6 +16,7 @@
 
 import pytest
 
+from neo4j_graphrag.experimental.pipeline import Component
 from neo4j_graphrag.experimental.pipeline.types.context import RunContext
 from .components import ComponentMultiply, ComponentMultiplyWithContext, IntResultModel
 
@@ -73,3 +74,16 @@ async def test_component_run_with_context() -> None:
     )
     assert result.result == 2
     notifier_mock.assert_awaited_once()
+
+
+def test_component_missing_method() -> None:
+    with pytest.raises(RuntimeError) as e:
+
+        class WrongComponent(Component):
+            # we must have either run or run_with_context
+            pass
+
+    assert (
+        "You must implement either `run` or `run_with_context` in Component 'WrongComponent'"
+        in str(e)
+    )