test: No warnings (googleapis#9)

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
- [x] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/python-db-dtypes-pandas/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)

Fixes googleapis#2 🦕

This builds-on/includes googleapis#8, which builds-on/includes googleapis#7.

Author: Jim Fulton

db_dtypes/__init__.py

@@ -16,8 +16,10 @@
 """
 
 import datetime
+import re
 
 import numpy
+import packaging.version
 import pandas
 import pandas.compat.numpy.function
 import pandas.core.algorithms
@@ -35,6 +37,8 @@
 date_dtype_name = "date"
 time_dtype_name = "time"
 
+pandas_release = packaging.version.parse(pandas.__version__).release
+
 
 @pandas.core.dtypes.dtypes.register_extension_dtype
 class TimeDtype(core.BaseDatetimeDtype):
@@ -61,15 +65,33 @@ class TimeArray(core.BaseDatetimeArray):
     _npepoch = numpy.datetime64(_epoch)
 
     @classmethod
-    def _datetime(cls, scalar):
+    def _datetime(
+        cls,
+        scalar,
+        match_fn=re.compile(
+            r"\s*(?P<hour>\d+)(?::(?P<minute>\d+)(?::(?P<second>\d+(?:[.]\d+)?)?)?)?\s*$"
+        ).match,
+    ):
         if isinstance(scalar, datetime.time):
             return datetime.datetime.combine(cls._epoch, scalar)
         elif isinstance(scalar, str):
             # iso string
-            h, m, s = map(float, scalar.split(":"))
-            s, us = divmod(s, 1)
+            match = match_fn(scalar)
+            if not match:
+                raise ValueError(f"Bad time string: {repr(scalar)}")
+
+            hour = match.group("hour")
+            minute = match.group("minute")
+            second = match.group("second")
+            second, microsecond = divmod(float(second if second else 0), 1)
             return datetime.datetime(
-                1970, 1, 1, int(h), int(m), int(s), int(us * 1000000)
+                1970,
+                1,
+                1,
+                int(hour),
+                int(minute if minute else 0),
+                int(second),
+                int(microsecond * 1_000_000),
             )
         else:
             raise TypeError("Invalid value type", scalar)
@@ -96,6 +118,11 @@ def astype(self, dtype, copy=True):
         else:
             return super().astype(dtype, copy=copy)
 
+    if pandas_release < (1,):
+
+        def to_numpy(self, dtype="object"):
+            return self.astype(dtype)
+
     def __arrow_array__(self, type=None):
         return pyarrow.array(
             self.to_numpy(), type=type if type is not None else pyarrow.time64("ns"),
@@ -125,12 +152,20 @@ class DateArray(core.BaseDatetimeArray):
     dtype = DateDtype()
 
     @staticmethod
-    def _datetime(scalar):
+    def _datetime(
+        scalar,
+        match_fn=re.compile(r"\s*(?P<year>\d+)-(?P<month>\d+)-(?P<day>\d+)\s*$").match,
+    ):
         if isinstance(scalar, datetime.date):
             return datetime.datetime(scalar.year, scalar.month, scalar.day)
         elif isinstance(scalar, str):
-            # iso string
-            return datetime.datetime(*map(int, scalar.split("-")))
+            match = match_fn(scalar)
+            if not match:
+                raise ValueError(f"Bad date string: {repr(scalar)}")
+            year = int(match.group("year"))
+            month = int(match.group("month"))
+            day = int(match.group("day"))
+            return datetime.datetime(year, month, day)
         else:
             raise TypeError("Invalid value type", scalar)
 

db_dtypes/core.py

@@ -84,6 +84,12 @@ def astype(self, dtype, copy=True):
         return super().astype(dtype, copy=copy)
 
     def _cmp_method(self, other, op):
+        oshape = getattr(other, "shape", None)
+        if oshape != self.shape and oshape != (1,) and self.shape != (1,):
+            raise TypeError(
+                "Can't compare arrays with different shapes", self.shape, oshape
+            )
+
         if type(other) != type(self):
             return NotImplemented
         return op(self._ndarray, other._ndarray)

db_dtypes/pandas_backports.py

@@ -31,8 +31,17 @@
 
 
 def import_default(module_name, force=False, default=None):
+    """
+    Provide an implementation for a class or function when it can't be imported
+
+    or when force is True.
+
+    This is used to replicate Pandas APIs that are missing or insufficient
+    (thus the force option) in early pandas versions.
+    """
+
     if default is None:
-        return lambda func: import_default(module_name, force, func)
+        return lambda func_or_class: import_default(module_name, force, func_or_class)
 
     if force:
         return default

testing/constraints-3.6.txt

@@ -5,6 +5,7 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 packaging==17.0
+# Make sure we test with pandas 0.24.2. The Python version isn't that relevant.
 pandas==0.24.2
 pyarrow==3.0.0
 numpy==1.16.6

testing/constraints-3.7.txt

@@ -1 +1,2 @@
+# Make sure we test with pandas 1.1.0. The Python version isn't that relevant.
 pandas==1.1.0

testing/constraints-3.8.txt

@@ -1 +1,2 @@
+# Make sure we test with pandas 1.2.0. The Python version isn't that relevant.
 pandas==1.2.0

tests/unit/test_dtypes.py

@@ -15,6 +15,7 @@
 import datetime
 
 import packaging.version
+import pyarrow.lib
 import pytest
 
 pd = pytest.importorskip("pandas")
@@ -171,18 +172,14 @@ def test_timearray_comparisons(
 
     # Bad shape
     for bad_shape in ([], [1, 2, 3]):
-        if op == "==":
-            assert not comparisons[op](left, np.array(bad_shape))
-            assert complements[op](left, np.array(bad_shape))
-        else:
-            with pytest.raises(
-                ValueError, match="operands could not be broadcast together",
-            ):
-                comparisons[op](left, np.array(bad_shape))
-            with pytest.raises(
-                ValueError, match="operands could not be broadcast together",
-            ):
-                complements[op](left, np.array(bad_shape))
+        with pytest.raises(
+            TypeError, match="Can't compare arrays with different shapes"
+        ):
+            comparisons[op](left, np.array(bad_shape))
+        with pytest.raises(
+            TypeError, match="Can't compare arrays with different shapes"
+        ):
+            complements[op](left, np.array(bad_shape))
 
     # Bad items
     for bad_items in (
@@ -478,8 +475,10 @@ def test_asdatetime(dtype, same):
 )
 def test_astimedelta(dtype):
     t = "01:02:03.123456"
-    expect = pd.to_timedelta([t]).array.astype(
-        "timedelta64[ns]" if dtype == "timedelta" else dtype
+    expect = (
+        pd.to_timedelta([t])
+        .to_numpy()
+        .astype("timedelta64[ns]" if dtype == "timedelta" else dtype)
     )
 
     a = _cls("time")([t, None])
@@ -543,7 +542,10 @@ def test_min_max_median(dtype):
     assert empty.min(skipna=False) is None
     assert empty.max(skipna=False) is None
     if pandas_release >= (1, 2):
-        assert empty.median() is None
+        with pytest.warns(RuntimeWarning, match="empty slice"):
+            # It's weird that we get the warning here, and not
+            # below. :/
+            assert empty.median() is None
         assert empty.median(skipna=False) is None
 
     a = _make_one(dtype)
@@ -620,3 +622,61 @@ def test_date_sub():
     do = pd.Series([pd.DateOffset(days=i) for i in range(4)])
     expect = dates.astype("object") - do
     assert np.array_equal(dates - do, expect)
+
+
+@pytest.mark.parametrize(
+    "value, expected", [("1", datetime.time(1)), ("1:2", datetime.time(1, 2))],
+)
+def test_short_time_parsing(value, expected):
+    assert _cls("time")([value])[0] == expected
+
+
+@pytest.mark.parametrize(
+    "value, error",
+    [
+        ("thursday", "Bad time string: 'thursday'"),
+        ("1:2:3thursday", "Bad time string: '1:2:3thursday'"),
+        ("1:2:3:4", "Bad time string: '1:2:3:4'"),
+        ("1:2:3.f", "Bad time string: '1:2:3.f'"),
+        ("1:d:3", "Bad time string: '1:d:3'"),
+        ("1:2.3", "Bad time string: '1:2.3'"),
+        ("", "Bad time string: ''"),
+        ("1:2:99", "second must be in 0[.][.]59"),
+        ("1:99", "minute must be in 0[.][.]59"),
+        ("99", "hour must be in 0[.][.]23"),
+    ],
+)
+def test_bad_time_parsing(value, error):
+    with pytest.raises(ValueError, match=error):
+        _cls("time")([value])
+
+
+@pytest.mark.parametrize(
+    "value, error",
+    [
+        ("thursday", "Bad date string: 'thursday'"),
+        ("1-2-thursday", "Bad date string: '1-2-thursday'"),
+        ("1-2-3-4", "Bad date string: '1-2-3-4'"),
+        ("1-2-3.f", "Bad date string: '1-2-3.f'"),
+        ("1-d-3", "Bad date string: '1-d-3'"),
+        ("1-3", "Bad date string: '1-3'"),
+        ("1", "Bad date string: '1'"),
+        ("", "Bad date string: ''"),
+        ("2021-2-99", "day is out of range for month"),
+        ("2021-99-1", "month must be in 1[.][.]12"),
+        ("10000-1-1", "year 10000 is out of range"),
+    ],
+)
+def test_bad_date_parsing(value, error):
+    with pytest.raises(ValueError, match=error):
+        _cls("date")([value])
+
+
+@for_date_and_time
+def test_date___arrow__array__(dtype):
+    a = _make_one(dtype)
+    ar = a.__arrow_array__()
+    assert isinstance(
+        ar, pyarrow.Date32Array if dtype == "date" else pyarrow.Time64Array,
+    )
+    assert [v.as_py() for v in ar] == list(a)