Add tests for missing __init__ and super().__init__() in custom nodes (#2350)

* Add tests for missing init and super

* Update Documentation & Code Style

* change in with endswith

* Move test in pipeline.py and change test in pipeline_yaml.py

* Update Documentation & Code Style

* Use caplog to test the warning

* Update Documentation & Code Style

* move tests into test_pipeline and use get_config

* Update Documentation & Code Style

* Unmock version name

* Update Documentation & Code Style

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

haystack/nodes/base.py

@@ -37,7 +37,10 @@ def exportable_to_yaml(init_func):
             self._component_config = {"params": {}, "type": type(self).__name__}
 
         # Make sure it runs only on the __init__of the implementations, not in superclasses
-        if init_func.__qualname__ == f"{self.__class__.__name__}.{init_func.__name__}":
+        # NOTE: we use '.endswith' because inner classes's __qualname__ will include the parent class'
+        #   name, like: ParentClass.InnerClass.__init__.
+        #   Inner classes are heavily used in tests.
+        if init_func.__qualname__.endswith(f"{self.__class__.__name__}.{init_func.__name__}"):
 
             # Store all the named input parameters in self._component_config
             for k, v in kwargs.items():

haystack/utils/import_utils.py

@@ -54,7 +54,8 @@ def _optional_component_not_installed(component: str, dep_group: str, source_err
         f"Failed to import '{component}', "
         "which is an optional component in Haystack.\n"
         f"Run 'pip install 'farm-haystack[{dep_group}]'' "
-        "to install the required dependencies and make this component available."
+        "to install the required dependencies and make this component available.\n"
+        f"(Original error: {str(source_error)})"
     ) from source_error
 
 

test/test_pipeline.py

@@ -35,6 +35,7 @@ from .conftest import (
     SAMPLES_PATH,
     MockDocumentStore,
     MockRetriever,
+    MockNode,
     deepset_cloud_fixture,
 )
 
@@ -350,6 +351,36 @@ def test_get_config_component_with_superclass_arguments():
     assert pipeline.get_document_store().base_parameter == "something"
 
 
+def test_get_config_custom_node_with_params():
+    class CustomNode(MockNode):
+        def __init__(self, param: int):
+            super().__init__()
+            self.param = param
+
+    pipeline = Pipeline()
+    pipeline.add_node(CustomNode(param=10), name="custom_node", inputs=["Query"])
+
+    assert len(pipeline.get_config()["components"]) == 1
+    assert pipeline.get_config()["components"][0]["params"] == {"param": 10}
+
+
+def test_get_config_custom_node_with_positional_params(caplog):
+    class CustomNode(MockNode):
+        def __init__(self, param: int = 1):
+            super().__init__()
+            self.param = param
+
+    pipeline = Pipeline()
+    with caplog.at_level(logging.WARNING):
+        pipeline.add_node(CustomNode(10), name="custom_node", inputs=["Query"])
+        assert (
+            "Unnamed __init__ parameters will not be saved to YAML "
+            "if Pipeline.save_to_yaml() is called" in caplog.text
+        )
+    assert len(pipeline.get_config()["components"]) == 1
+    assert pipeline.get_config()["components"][0]["params"] == {}
+
+
 def test_generate_code_simple_pipeline():
     config = {
         "version": "unstable",

test/test_pipeline_yaml.py

@@ -1,6 +1,8 @@
 from abc import abstractmethod
+from numpy import mat
 import pytest
 import json
+import logging
 import inspect
 import networkx as nx
 from enum import Enum
@@ -11,6 +13,7 @@ from haystack import Pipeline
 from haystack.nodes import _json_schema
 from haystack.nodes import FileTypeClassifier
 from haystack.errors import HaystackError, PipelineConfigError, PipelineSchemaError
+from haystack.nodes.base import BaseComponent
 
 from .conftest import SAMPLES_PATH, MockNode, MockDocumentStore, MockReader, MockRetriever
 from . import conftest
@@ -41,7 +44,9 @@ def mock_json_schema(request, monkeypatch, tmp_path):
 
     # Generate mock schema in tmp_path
     filename = f"haystack-pipeline-unstable.schema.json"
-    test_schema = _json_schema.get_json_schema(filename=filename, compatible_versions=["unstable"])
+    test_schema = _json_schema.get_json_schema(
+        filename=filename, compatible_versions=["unstable", haystack.__version__]
+    )
 
     with open(tmp_path / filename, "w") as schema_file:
         json.dump(test_schema, schema_file, indent=4)
@@ -274,11 +279,65 @@ def test_load_yaml_custom_component(tmp_path):
     assert pipeline.get_node("custom_node").param == 1
 
 
+def test_load_yaml_custom_component_with_no_init(tmp_path):
+    class CustomNode(MockNode):
+        pass
+
+    with open(tmp_path / "tmp_config.yml", "w") as tmp_file:
+        tmp_file.write(
+            f"""
+            version: unstable
+            components:
+            - name: custom_node
+              type: CustomNode
+            pipelines:
+            - name: my_pipeline
+              nodes:
+              - name: custom_node
+                inputs:
+                - Query
+        """
+        )
+    pipeline = Pipeline.load_from_yaml(path=tmp_path / "tmp_config.yml")
+    assert isinstance(pipeline.get_node("custom_node"), CustomNode)
+
+
+def test_load_yaml_custom_component_neednt_call_super(tmp_path):
+    """This is a side-effect. Here for behavior documentation only"""
+
+    class CustomNode(BaseComponent):
+        outgoing_edges = 1
+
+        def __init__(self, param: int):
+            self.param = param
+
+        def run(self, *a, **k):
+            pass
+
+    with open(tmp_path / "tmp_config.yml", "w") as tmp_file:
+        tmp_file.write(
+            f"""
+            version: unstable
+            components:
+            - name: custom_node
+              type: CustomNode
+              params:
+                param: 1
+            pipelines:
+            - name: my_pipeline
+              nodes:
+              - name: custom_node
+                inputs:
+                - Query
+        """
+        )
+    pipeline = Pipeline.load_from_yaml(path=tmp_path / "tmp_config.yml")
+    assert isinstance(pipeline.get_node("custom_node"), CustomNode)
+    assert pipeline.get_node("custom_node").param == 1
+
+
 def test_load_yaml_custom_component_cant_be_abstract(tmp_path):
     class CustomNode(MockNode):
-        def __init__(self):
-            super().__init__()
-
         @abstractmethod
         def abstract_method(self):
             pass
@@ -575,7 +634,7 @@ def test_load_yaml_custom_component_with_external_constant(tmp_path):
         )
     pipeline = Pipeline.load_from_yaml(path=tmp_path / "tmp_config.yml")
     node = pipeline.get_node("custom_node")
-    node.some_exotic_parameter == "AnotherClass.CLASS_CONSTANT"
+    assert node.some_exotic_parameter == "AnotherClass.CLASS_CONSTANT"
 
 
 def test_load_yaml_custom_component_with_superclass(tmp_path):