TST: GH30999 Add match=msg to all pytest.raises in tests/reductions and add an error message to nanmedian (#38720)

Author: moink

pandas/core/nanops.py

@@ -685,7 +685,7 @@ def get_median(x):
  values = values.astype("f8")
  except ValueError as err:
  # e.g. "could not convert string to float: 'a'"
- raise TypeError from err
+ raise TypeError(str(err)) from err
  if mask is not None:
  values[mask] = np.nan
 

pandas/tests/reductions/test_reductions.py

@@ -527,9 +527,17 @@ def test_numpy_minmax_period(self):
  def test_min_max_categorical(self):
 
  ci = pd.CategoricalIndex(list("aabbca"), categories=list("cab"), ordered=False)
- with pytest.raises(TypeError):
+ msg = (
+ r"Categorical is not ordered for operation min\n"
+ r"you can use .as_ordered\(\) to change the Categorical to an ordered one\n"
+ )
+ with pytest.raises(TypeError, match=msg):
  ci.min()
- with pytest.raises(TypeError):
+ msg = (
+ r"Categorical is not ordered for operation max\n"
+ r"you can use .as_ordered\(\) to change the Categorical to an ordered one\n"
+ )
+ with pytest.raises(TypeError, match=msg):
  ci.max()
 
  ci = pd.CategoricalIndex(list("aabbca"), categories=list("cab"), ordered=True)
@@ -881,16 +889,20 @@ def test_all_any_params(self):
  tm.assert_series_equal(s.all(level=0), Series([False, True, False]))
  tm.assert_series_equal(s.any(level=0), Series([False, True, True]))
 
- # bool_only is not implemented with level option.
- with pytest.raises(NotImplementedError):
+ msg = "Option bool_only is not implemented with option level"
+ with pytest.raises(NotImplementedError, match=msg):
  s.any(bool_only=True, level=0)
- with pytest.raises(NotImplementedError):
+ with pytest.raises(NotImplementedError, match=msg):
  s.all(bool_only=True, level=0)
 
  # bool_only is not implemented alone.
- with pytest.raises(NotImplementedError):
+ # TODO GH38810 change this error message to:
+ # "Series.any does not implement bool_only"
+ msg = "Series.any does not implement numeric_only"
+ with pytest.raises(NotImplementedError, match=msg):
  s.any(bool_only=True)
- with pytest.raises(NotImplementedError):
+ msg = "Series.all does not implement numeric_only."
+ with pytest.raises(NotImplementedError, match=msg):
  s.all(bool_only=True)
 
  def test_all_any_boolean(self):
@@ -1023,13 +1035,21 @@ def test_assert_idxminmax_raises(self, test_input, error_type):
  """
  Cases where ``Series.argmax`` and related should raise an exception
  """
- with pytest.raises(error_type):
+ msg = (
+ "reduction operation 'argmin' not allowed for this dtype|"
+ "attempt to get argmin of an empty sequence"
+ )
+ with pytest.raises(error_type, match=msg):
  test_input.idxmin()
- with pytest.raises(error_type):
+ with pytest.raises(error_type, match=msg):
  test_input.idxmin(skipna=False)
- with pytest.raises(error_type):
+ msg = (
+ "reduction operation 'argmax' not allowed for this dtype|"
+ "attempt to get argmax of an empty sequence"
+ )
+ with pytest.raises(error_type, match=msg):
  test_input.idxmax()
- with pytest.raises(error_type):
+ with pytest.raises(error_type, match=msg):
  test_input.idxmax(skipna=False)
 
  def test_idxminmax_with_inf(self):

pandas/tests/reductions/test_stat_reductions.py

@@ -98,7 +98,8 @@ def _check_stat_op(
  # mean, idxmax, idxmin, min, and max are valid for dates
  if name not in ["max", "min", "mean", "median", "std"]:
  ds = Series(pd.date_range("1/1/2001", periods=10))
- with pytest.raises(TypeError):
+ msg = f"'DatetimeArray' does not implement reduction '{name}'"
+ with pytest.raises(TypeError, match=msg):
  f(ds)
 
  # skipna or no
@@ -134,11 +135,12 @@ def _check_stat_op(
 
  # check on string data
  if name not in ["sum", "min", "max"]:
- with pytest.raises(TypeError):
+ with pytest.raises(TypeError, match=None):
  f(Series(list("abc")))
 
  # Invalid axis.
- with pytest.raises(ValueError):
+ msg = "No axis named 1 for object type Series"
+ with pytest.raises(ValueError, match=msg):
  f(string_series_, axis=1)
 
  # Unimplemented numeric_only parameter.