added unit tests for _call_fit

added unit tests for _call_fit to test_pipeline

Author: vzaretsk

tests/test_pipeline.py

@@ -1,5 +1,13 @@
 import pytest
-from sklearn_pandas.pipeline import TransformerPipeline
+from sklearn_pandas.pipeline import TransformerPipeline, _call_fit
+from functools import partial
+
+# In py3, mock is included with the unittest standard library
+# In py2, it's a separate package
+try:
+    from unittest.mock import patch
+except ImportError:
+    from mock import patch
 
 
 class NoTransformT(object):
@@ -16,6 +24,39 @@ def transform(self, x):
         return self
 
 
+class Trans(object):
+    """
+    Transformer with fit and transform methods
+    """
+    def fit(self, x, y=None):
+        return self
+
+    def transform(self, x):
+        return self
+
+
+def func_x_y(x, y, kwarg='kwarg'):
+    """
+    Function with required x and y arguments
+    """
+    return
+
+
+def func_x(x, kwarg='kwarg'):
+    """
+    Function with required x argument
+    """
+    return
+
+
+def func_raise_type_err(x, y, kwarg='kwarg'):
+    """
+    Function with required x and y arguments,
+    raises TypeError
+    """
+    raise TypeError
+
+
 def test_all_steps_fit_transform():
     """
     All steps must implement fit and transform. Otherwise, raise TypeError.
@@ -25,3 +66,36 @@ def test_all_steps_fit_transform():
 
     with pytest.raises(TypeError):
         TransformerPipeline([('svc', NoFitT())])
+
+
+@patch.object(Trans, 'fit', side_effect=func_x_y)
+def test_called_with_x_and_y(mock_fit):
+    """
+    Fit method with required X and y arguments is called with both and with
+    any additional keywords
+    """
+    _call_fit(Trans().fit, 'X', 'y', kwarg='kwarg')
+    mock_fit.assert_called_with('X', 'y', kwarg='kwarg')
+
+
+@patch.object(Trans, 'fit', side_effect=func_x)
+def test_called_with_x(mock_fit):
+    """
+    Fit method with a required X arguments is called with it and with
+    any additional keywords
+    """
+    _call_fit(Trans().fit, 'X', 'y', kwarg='kwarg')
+    mock_fit.assert_called_with('X', kwarg='kwarg')
+
+    _call_fit(Trans().fit, 'X', kwarg='kwarg')
+    mock_fit.assert_called_with('X', kwarg='kwarg')
+
+
+@patch.object(Trans, 'fit', side_effect=func_raise_type_err)
+def test_raises_type_error(mock_fit):
+    """
+    If a fit method with required X and y arguments raises a TypeError, it's
+    re-raised (for a different reason) when it's called with one argument
+    """
+    with pytest.raises(TypeError):
+        _call_fit(Trans().fit, 'X', 'y', kwarg='kwarg')