Merge pull request #5362 from TomAugspurger/interp_dtype_infer

TST: interpolate precision inference

Author: jreback

pandas/tests/test_generic.py

@@ -478,9 +478,9 @@ def test_nan_str_index(self):
     def test_interp_quad(self):
         _skip_if_no_scipy()
         sq = Series([1, 4, np.nan, 16], index=[1, 2, 3, 4])
-        result = sq.interpolate(method='quadratic')
-        expected = Series([1, 4, 9, 16], index=[1, 2, 3, 4])
-        assert_series_equal(result, expected)
+        result = sq.interpolate(method='quadratic', downcast=False)
+        expected = Series([1., 4, 9, 16], index=[1, 2, 3, 4])
+        assert_series_equal(result, expected, check_less_precise=True)
 
     def test_interp_scipy_basic(self):
         _skip_if_no_scipy()