FIX: Raise errors when wrong string arguments are passed to resample (#19307)

Author: cchwala

doc/source/whatsnew/v0.23.0.txt

@@ -486,7 +486,7 @@ Groupby/Resample/Rolling
 
 - Bug when grouping by a single column and aggregating with a class like ``list`` or ``tuple`` (:issue:`18079`)
 - Fixed regression in :func:`DataFrame.groupby` which would not emit an error when called with a tuple key not in the index (:issue:`18798`)
--
+- Bug in :func:`DataFrame.resample` which silently ignored unsupported (or mistyped) options for ``label``, ``closed`` and ``convention`` (:issue:`19303`)
 -
 
 Sparse

pandas/core/resample.py

@@ -1061,6 +1061,17 @@ class TimeGrouper(Grouper):
     def __init__(self, freq='Min', closed=None, label=None, how='mean',
                  axis=0, fill_method=None, limit=None, loffset=None,
                  kind=None, convention=None, base=0, **kwargs):
+        # Check for correctness of the keyword arguments which would
+        # otherwise silently use the default if misspelled
+        if label not in {None, 'left', 'right'}:
+            raise ValueError('Unsupported value {} for `label`'.format(label))
+        if closed not in {None, 'left', 'right'}:
+            raise ValueError('Unsupported value {} for `closed`'.format(
+                closed))
+        if convention not in {None, 'start', 'end', 'e', 's'}:
+            raise ValueError('Unsupported value {} for `convention`'
+                             .format(convention))
+
         freq = to_offset(freq)
 
         end_types = set(['M', 'A', 'Q', 'BM', 'BA', 'BQ', 'W'])

pandas/tests/test_resample.py

@@ -963,6 +963,7 @@ def test_resample_basic(self):
         rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
                          name='index')
         s = Series(np.random.randn(14), index=rng)
+
         result = s.resample('5min', closed='right', label='right').mean()
 
         exp_idx = date_range('1/1/2000', periods=4, freq='5min', name='index')
@@ -985,6 +986,20 @@ def test_resample_basic(self):
         expect = s.groupby(grouper).agg(lambda x: x[-1])
         assert_series_equal(result, expect)
 
+    def test_resample_string_kwargs(self):
+        # Test for issue #19303
+        rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
+                         name='index')
+        s = Series(np.random.randn(14), index=rng)
+
+        # Check that wrong keyword argument strings raise an error
+        with pytest.raises(ValueError):
+            s.resample('5min', label='righttt').mean()
+        with pytest.raises(ValueError):
+            s.resample('5min', closed='righttt').mean()
+        with pytest.raises(ValueError):
+            s.resample('5min', convention='starttt').mean()
+
     def test_resample_how(self):
         rng = date_range('1/1/2000 00:00:00', '1/1/2000 00:13:00', freq='min',
                          name='index')