Repository: MAIF/melusine

Issue:
🥅 améliorer un message de raise + minor updates dans la doc (contributing.md ..)
**Description of Problem:**

https://github.com/MAIF/melusine/blob/18ab6e68346688beb84317c7bba33b4d7f2f526d/melusine/pipeline.py#L224

```python
melusine/pipeline.py:224: 
raise TypeError(f"Object {obj_class} does not inherit from the SaverMixin class")  # pragma: no cover 
```
reference à SaverMixin alors que la classe n'est pas définie.

**Overview of the Solution**
Remplacer par IoMixin et faire quelques updates dans la doc (lien mort)

**Definition of Done**
Documentation et correction du message de raise

Hints from issue comments:
@HugoPerrier: Je propose de modifier la condition sur l'héritage IoMixin (issubclass) par une condition sur la présence d'une méthode from_config.

Solution patch:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 2a0fb7d..a91edc5 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -43,10 +43,10 @@ repos:
     -   id: flake8
         additional_dependencies: [ flake8-docstrings, "flake8-bugbear==22.8.23" ]
 
-- repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.1.11
-  hooks:
-    - id: ruff
+-   repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.1.11
+    hooks:
+    -   id: ruff
 
 -   repo: https://github.com/pre-commit/mirrors-isort
     rev: v5.10.1
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c1c99a1..f28e174 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -28,18 +28,15 @@ Next, the Melusine team, or the community, will give you a feedback on whether y
 
 ## Fork to code in your personal Melusine repo
 
-The first step is to get our MAIF repository on your personal GitHub repositories. To do so, use the "Fork" button.
+The first step is to get our MAIF repository on your personal GitHub repositories. To do so, use the "Fork" button on Github landing page of melusine project.
 
-<img src="https://raw.githubusercontent.com/MAIF/melusine/master/docs/assets/images/contributing/fork_melusine.PNG" alt="fork this repository" />
 
 ## Clone your forked repository
 
-<img align="right" width="300" src="https://raw.githubusercontent.com/MAIF/melusine/master/docs/assets/images/contributing/clone_melusine.PNG" alt="clone your forked repository" />
-
 Click on the "Code" button to copy the url of your repository, and next, you can paste this url to clone your forked repository.
 
 ```
-git clone https://github.com/YOUR_GITHUB_PROFILE/melusine.git
+git clone https://github.com/<YOUR_GITHUB_PROFILE>/melusine.git
 ```
 
 ## Make sure that your repository is up-to-date
@@ -137,9 +134,7 @@ Your branch is now available on your remote forked repository, with your changes
 
 A pull request allows you to ask the Melusine team to review your changes, and merge your changes into the master branch of the official repository.
 
-To create one, on the top of your forked repository, you will find a button "Compare & pull request"
-
-<img src="https://raw.githubusercontent.com/MAIF/melusine/master/docs/assets/images/contributing/melusine-compare-pr.png" alt="pull request" />
+To create one, on the top of your forked repository, you will find a button "Compare & pull request".
 
 As you can see, you can select on the right side which branch of your forked repository you want to associate to the pull request.
 
@@ -150,12 +145,7 @@ On the left side, you will find the official Melusine repository. Due to increas
 - Head repository: your-github-username/melusine
 - Head branch: your-contribution-branch
 
-<img src="https://raw.githubusercontent.com/MAIF/melusine/master/docs/assets/images/contributing/melusine-pr-branch.png" alt="clone your forked repository" />
-
 Once you have selected the right branch, let's create the pull request with the green button "Create pull request".
-
-<img src="https://raw.githubusercontent.com/MAIF/melusine/master/docs/assets/images/contributing/melusine-pr-description.png" alt="clone your forked repository" />
-
 In the description, a template is initialized with all information you have to give about what you are doing on what your PR is doing.
 
 Please follow this to write your PR content.
diff --git a/melusine/__init__.py b/melusine/__init__.py
index e33be5c..49745e1 100644
--- a/melusine/__init__.py
+++ b/melusine/__init__.py
@@ -8,7 +8,7 @@
 
 __all__ = ["config"]
 
-VERSION = (3, 1, 0)
+VERSION = (3, 1, 1)
 __version__ = ".".join(map(str, VERSION))
 
 # ------------------------------- #
diff --git a/melusine/pipeline.py b/melusine/pipeline.py
index bead973..3a3ed10 100644
--- a/melusine/pipeline.py
+++ b/melusine/pipeline.py
@@ -8,6 +8,7 @@
 
 import copy
 import importlib
+import warnings
 from typing import Iterable, TypeVar
 
 from sklearn.pipeline import Pipeline
@@ -35,7 +36,7 @@ class MelusinePipeline(Pipeline):
     """
 
     OBJ_NAME: str = "name"
-    OBJ_KEY: str = "config_key"
+    OBJ_CONFIG_KEY: str = "config_key"
     OBJ_PARAMS: str = "parameters"
     STEPS_KEY: str = "steps"
     OBJ_CLASS: str = "class_name"
@@ -194,10 +195,10 @@ def from_config(
         # Get config dict
         if config_key and not config_dict:
             raw_config_dict = config[config_key]
-            config_dict = cls.parse_pipeline_config(raw_config_dict)
+            config_dict = cls.parse_pipeline_config(config_dict=raw_config_dict)
 
         elif config_dict and not config_key:
-            config_dict = cls.parse_pipeline_config(config_dict)
+            config_dict = cls.parse_pipeline_config(config_dict=config_dict)
         else:
             raise ValueError("You should specify one and only one of 'config_key' and 'config_dict'")
 
@@ -218,10 +219,33 @@ def from_config(
             # Step arguments
             obj_params = obj_meta[cls.OBJ_PARAMS]
 
-            if issubclass(obj_class, IoMixin):
+            # Verbose option
+            suppress_warnings: Any = kwargs.pop("suppress_warnings", False)
+
+            try:
                 obj = obj_class.from_config(config_dict=obj_params)
-            else:
-                raise TypeError(f"Object {obj_class} does not inherit from the SaverMixin class")  # pragma: no cover
+                if not issubclass(obj_class, IoMixin) and not suppress_warnings:
+                    type_warn_msg: str = f"""
+                        It seems you are not using a melusine object in your melusine pipeline, but object '{obj_class}' (class {type(obj_class)}) for step '{step_name}'.
+                        The expected behavior is not guaranteed and can break in future version of melusine.
+
+                        Recommended usage:
+                            - Exclusive usage of melusine class Pipeline with melusine objects (MelusineTransformer, MelusineDetector...)
+
+                        To suppress this warning, instanciate melusine Pipeline with suppress_warnings argument at True (MelusinePipeline.from_config(..., suppress_warnings=True)).
+
+                        Visit Melusine Open-Source project: https://github.com/MAIF/melusine and the documentation for more information.
+                    """
+                    warnings.warn(message=type_warn_msg, category=DeprecationWarning, stacklevel=2)
+            except AttributeError as err:
+                if not hasattr(obj_class, "from_config"):
+                    raise AttributeError(
+                        f"Object '{obj_class}' does not implement 'from_config' method, maybe consider to inherit it from the Melusine IoMixin class or use a MelusineTransformer class."
+                    ) from None
+                else:
+                    raise AttributeError(f"Error in loading class: '{obj_class}'\\n{str(err)}").with_traceback(
+                        err.__traceback__
+                    ) from err
 
             # Add step to pipeline
             steps.append((step_name, obj))
@@ -251,17 +275,17 @@ def validate_step_config(cls, step: dict[str, Any]) -> dict[str, Any]:
                 f"Pipeline step conf should have a {cls.OBJ_MODULE} key and a {cls.OBJ_CLASS} key."
             )
 
-        if step.get(cls.OBJ_KEY):
+        if step.get(cls.OBJ_CONFIG_KEY):
             return {
                 cls.OBJ_CLASS: step[cls.OBJ_CLASS],
                 cls.OBJ_MODULE: step[cls.OBJ_MODULE],
-                cls.OBJ_KEY: step[cls.OBJ_KEY],
+                cls.OBJ_CONFIG_KEY: step[cls.OBJ_CONFIG_KEY],
             }
 
         if not step.get(cls.OBJ_NAME) or not step.get(cls.OBJ_PARAMS):
             raise PipelineConfigurationError(
-                f"Pipeline step conf should have a {cls.OBJ_NAME} key and a {cls.OBJ_KEY} key "
-                f"(unless a {cls.OBJ_KEY} is specified)."
+                f"Pipeline step conf should have a {cls.OBJ_NAME} key and a {cls.OBJ_CONFIG_KEY} key "
+                f"(unless a {cls.OBJ_CONFIG_KEY} is specified)."
             )
 
         if not isinstance(step[cls.OBJ_PARAMS], dict):
@@ -325,11 +349,12 @@ def parse_pipeline_config(cls, config_dict: dict[str, Any]) -> dict[str, Any]:
         steps = []
         for step in config_dict[cls.STEPS_KEY]:
             # Step defined from the config
-            config_key = step.get(cls.OBJ_KEY)
+            config_key = step.get(cls.OBJ_CONFIG_KEY)
+            config_name = step.get(cls.OBJ_NAME)
             if config_key:
-                # Use config key as step name
-                step[cls.OBJ_NAME] = config_key
-                _ = step.pop(cls.OBJ_KEY)
+                # Use config key as step name if no name is provided in config
+                step[cls.OBJ_NAME] = config_name or config_key
+                _ = step.pop(cls.OBJ_CONFIG_KEY)
                 # Update step parameters
                 step[cls.OBJ_PARAMS] = config[config_key]
 


Test patch:
diff --git a/tests/pipeline/test_pipeline_basic.py b/tests/pipeline/test_pipeline_basic.py
index d2b2f25..73db444 100644
--- a/tests/pipeline/test_pipeline_basic.py
+++ b/tests/pipeline/test_pipeline_basic.py
@@ -1,6 +1,8 @@
 """
 Example script to fit a minimal preprocessing pipeline
 """
+from contextlib import nullcontext as does_not_raise
+from unittest import mock
 
 import pandas as pd
 import pytest
@@ -34,7 +36,7 @@ def test_pipeline_basic(dataframe_basic):
 @pytest.mark.usefixtures("use_test_config")
 def test_pipeline_from_config(dataframe_basic):
     """
-    Train a pipeline using transformers defined in a pipeline config file.
+    Train a pipeline using scikit-learn transformers defined in a pipeline config file.
     """
     # Input data
     df = dataframe_basic.copy()
@@ -79,7 +81,7 @@ def test_pipeline_from_config(dataframe_basic):
 @pytest.mark.usefixtures("use_test_config")
 def test_pipeline_from_dict(dataframe_basic):
     """
-    Train a pipeline using transformers defined in a pipeline config file.
+    Train a pipeline using scikit-learn transformers defined in a pipeline config file.
     """
     # Input data
     df = dataframe_basic.copy()
@@ -125,7 +127,7 @@ def test_pipeline_from_dict(dataframe_basic):
 @pytest.mark.usefixtures("use_test_config")
 def test_missing_config_key():
     """
-    Train a pipeline using transformers defined in a pipeline config file.
+    Train a pipeline using scikit-learn transformers defined in a pipeline config file.
     """
     # Set config keys
     normalizer_name = "normalizer"
@@ -159,7 +161,7 @@ def test_missing_config_key():
 @pytest.mark.usefixtures("use_test_config")
 def test_invalid_config_key():
     """
-    Train a pipeline using transformers defined in a pipeline config file.
+    Train a pipeline using scikit-learn transformers defined in a pipeline config file.
     """
     incorrect_config_key = "INCORRECT_CONFIG_KEY"
 
@@ -263,7 +265,7 @@ def test_invalid_config_key():
 )
 def test_pipeline_config_error(pipeline_conf):
     """
-    Train a pipeline using transformers defined in a pipeline config file.
+    Train a pipeline using scikit-learn transformers defined in a pipeline config file.
     """
     # Create pipeline from a json config file (using config key "my_pipeline")
     with pytest.raises(PipelineConfigurationError):
@@ -313,3 +315,117 @@ def test_missing_input_field(dataframe_basic):
     # Fit the pipeline and transform the data
     with pytest.raises(ValueError, match=rf"(?s){tokenizer_name}.*{missing_field_name}"):
         pipe.transform(df)
+
+
+@pytest.mark.usefixtures("use_test_config")
+def test_pipeline_from_config_with_error():
+    """
+    Instanciate a Melusine Pipeline not using scikit-learn transformers defined in a pipeline config file (raising errors).
+    """
+    # Set config keys
+    normalizer_key = "test_normalizer"
+    pipeline_key = "test_pipeline"
+
+    # Pipeline configuration
+    conf_pipeline_basic = {
+        "steps": [
+            {
+                "class_name": "Normalizer",
+                "module": "melusine.processors",
+                "config_key": normalizer_key,
+            },
+        ]
+    }
+
+    test_conf_dict = config.dict()
+    test_conf_dict[pipeline_key] = conf_pipeline_basic
+    config.reset(config_dict=test_conf_dict)
+
+    with mock.patch("melusine.pipeline.MelusinePipeline.import_class") as mock_import_class, pytest.raises(
+        AttributeError, match=r"Object '.+' does not implement 'from_config'.+to inherit it from the Melusine IoMixin.+"
+    ):
+
+        class WrongNormalizerWithoutMethodFromConfig:
+            def __init__(self, form, input_columns, lowercase, output_columns) -> None:
+                """Mock class without from_config method so we raise error."""
+                return None
+
+        mock_import_class.return_value = WrongNormalizerWithoutMethodFromConfig
+
+        # Create pipeline from a json config file
+        _ = MelusinePipeline.from_config(config_key=pipeline_key, verbose=True)
+
+    with mock.patch("melusine.pipeline.MelusinePipeline.import_class") as mock_import_class, pytest.raises(
+        AttributeError
+    ) as e:
+
+        class WrongNormalizerWithMethodFromConfig:
+            def __init__(self) -> None:
+                return None
+
+            @classmethod
+            def from_config(cls, config_dict: dict):
+                """Mock method from_config so we have a valid 'duck typed' class but with attribute error."""
+
+                return cls.class_constant_not_defined_raising_attribute_error
+
+        mock_import_class.return_value = WrongNormalizerWithMethodFromConfig
+
+        # Create pipeline from a json config file
+        _ = MelusinePipeline.from_config(config_key=pipeline_key, verbose=True)
+
+    assert "does not implement 'from_config'" not in str(e)
+
+
+@pytest.mark.usefixtures("use_test_config")
+def test_pipeline_from_config_with_warning(recwarn):
+    """
+    Instanciate a Melusine Pipeline not using scikit-learn transformers defined in a pipeline config file (raising warnings).
+    """
+    # Set config keys
+    normalizer_key = "test_normalizer"
+    pipeline_key = "test_pipeline"
+
+    # Pipeline configuration
+    conf_pipeline_basic = {
+        "steps": [
+            {
+                "class_name": "Normalizer",
+                "module": "melusine.processors",
+                "config_key": normalizer_key,
+            },
+        ]
+    }
+
+    test_conf_dict = config.dict()
+    test_conf_dict[pipeline_key] = conf_pipeline_basic
+    config.reset(config_dict=test_conf_dict)
+
+    with mock.patch("melusine.pipeline.MelusinePipeline.import_class") as mock_import_class:
+
+        class WrongNormalizerWithMethodFromConfig:
+            def __init__(self) -> None:
+                return None
+
+            @classmethod
+            def from_config(cls, config_dict: dict):
+                """Mock method from_config so we have a valid 'duck typed' class but with invalid functional behavior."""
+                return cls
+
+        mock_import_class.return_value = WrongNormalizerWithMethodFromConfig
+
+        with does_not_raise():
+            # Create pipeline from a json config file and suppress warning
+            _ = MelusinePipeline.from_config(config_key=pipeline_key, verbose=True, suppress_warnings=True)
+
+        assert len(recwarn) == 0
+
+        _ = MelusinePipeline.from_config(config_key=pipeline_key, verbose=True, suppress_warnings=False)
+
+        assert len(recwarn) == 1
+
+        with pytest.warns(
+            DeprecationWarning, match=r".+It seems you are not using a melusine object in your melusine pipeline.+"
+        ):
+            # Create pipeline from a json config file
+            _ = MelusinePipeline.from_config(config_key=pipeline_key, verbose=True, suppress_warnings=False)