TST: Improve integration of Hypothesis

Responding to review from jreback on GH22280.

Author: Zac-HD

doc/source/contributing.rst

@@ -795,6 +795,8 @@ Tests that we have ``parametrized`` are now accessible via the test name, for ex
    test_cool_feature.py::test_series[int8] PASSED
 
 
+.. _using-hypothesis:
+
 Using ``hypothesis``
 ~~~~~~~~~~~~~~~~~~~~
 

pandas/conftest.py

@@ -453,3 +453,37 @@ def mock():
         return importlib.import_module("unittest.mock")
     else:
         return pytest.importorskip("mock")
+
+
+# ----------------------------------------------------------------
+# Global setup for tests using Hypothesis
+
+from hypothesis import strategies as st
+
+# Registering these strategies makes them globally available via st.from_type,
+# which is use for offsets in tests/tseries/offsets/test_offsets_properties.py
+for name in 'MonthBegin MonthEnd BMonthBegin BMonthEnd'.split():
+    cls = getattr(pd.tseries.offsets, name)
+    st.register_type_strategy(cls, st.builds(
+        cls,
+        n=st.integers(-99, 99),
+        normalize=st.booleans(),
+    ))
+
+for name in 'YearBegin YearEnd BYearBegin BYearEnd'.split():
+    cls = getattr(pd.tseries.offsets, name)
+    st.register_type_strategy(cls, st.builds(
+        cls,
+        n=st.integers(-5, 5),
+        normalize=st.booleans(),
+        month=st.integers(min_value=1, max_value=12),
+    ))
+
+for name in 'QuarterBegin QuarterEnd BQuarterBegin BQuarterEnd'.split():
+    cls = getattr(pd.tseries.offsets, name)
+    st.register_type_strategy(cls, st.builds(
+        cls,
+        n=st.integers(-24, 24),
+        normalize=st.booleans(),
+        startingMonth=st.integers(min_value=1, max_value=12)
+    ))

pandas/tests/tseries/offsets/test_offsets_properties.py

@@ -17,18 +17,11 @@
 import pandas as pd
 
 from pandas.tseries.offsets import (
-    Hour, Minute, Second, Milli, Micro, Nano,
     MonthEnd, MonthBegin, BMonthEnd, BMonthBegin,
     QuarterEnd, QuarterBegin, BQuarterEnd, BQuarterBegin,
     YearEnd, YearBegin, BYearEnd, BYearBegin,
 )
 
-
-tick_classes = [Hour, Minute, Second, Milli, Micro, Nano]
-yqm_classes = [MonthBegin, MonthEnd, BMonthBegin, BMonthEnd,
-               QuarterBegin, QuarterEnd, BQuarterBegin, BQuarterEnd,
-               YearBegin, YearEnd, BYearBegin, BYearEnd]
-
 # ----------------------------------------------------------------
 # Helpers for generating random data
 
@@ -50,35 +43,13 @@
     timezones=st.one_of(st.none(), dateutil_timezones(), pytz_timezones())
 )
 
-# Register the various offset classes so st.from_type can create instances.
-# We *could* just append the strategies to a list, but this provides a nice
-# demo and enables future tests to use a simple e.g. `from_type(Hour)`.
-for cls in tick_classes + [MonthBegin, MonthEnd, BMonthBegin, BMonthEnd]:
-    st.register_type_strategy(cls, st.builds(
-        cls,
-        n=st.integers(-99, 99),
-        normalize=st.booleans(),
-    ))
-
-for cls in [YearBegin, YearEnd, BYearBegin, BYearEnd]:
-    st.register_type_strategy(cls, st.builds(
-        cls,
-        n=st.integers(-5, 5),
-        normalize=st.booleans(),
-        month=st.integers(min_value=1, max_value=12),
-    ))
-
-for cls in [QuarterBegin, QuarterEnd, BQuarterBegin, BQuarterEnd]:
-    st.register_type_strategy(cls, st.builds(
-        cls,
-        n=st.integers(-24, 24),
-        normalize=st.booleans(),
-        startingMonth=st.integers(min_value=1, max_value=12)
-    ))
-
-# This strategy can generate any kind of Offset in `tick_classes` or
-# `yqm_classes`, with arguments as specified directly above in registration.
-gen_yqm_offset = st.one_of([st.from_type(cls) for cls in yqm_classes])
+# The strategy for each type is registered in conftest.py, as they don't carry
+# enough runtime information (e.g. type hints) to infer how to build them.
+gen_yqm_offset = st.one_of(*map(st.from_type, [
+    MonthBegin, MonthEnd, BMonthBegin, BMonthEnd,
+    QuarterBegin, QuarterEnd, BQuarterBegin, BQuarterEnd,
+    YearBegin, YearEnd, BYearBegin, BYearEnd
+]))
 
 
 # ----------------------------------------------------------------

pandas/tests/tseries/offsets/test_ticks.py

@@ -6,7 +6,7 @@
 
 import pytest
 import numpy as np
-from hypothesis import given, assume, strategies as st
+from hypothesis import given, assume, example, strategies as st
 
 from pandas import Timedelta, Timestamp
 from pandas.tseries import offsets
@@ -36,9 +36,11 @@ def test_delta_to_tick():
     assert (tick == offsets.Day(3))
 
 
-@given(cls=st.sampled_from(tick_classes),
-       n=st.integers(-999, 999),
-       m=st.integers(-999, 999))
+@pytest.mark.parametrize('cls', tick_classes)
+@example(n=2, m=3)
+@example(n=800, m=300)
+@example(n=1000, m=5)
+@given(n=st.integers(-999, 999), m=st.integers(-999, 999))
 def test_tick_add_sub(cls, n, m):
     # For all Tick subclasses and all integers n, m, we should have
     # tick(n) + tick(m) == tick(n+m)
@@ -54,8 +56,9 @@ def test_tick_add_sub(cls, n, m):
     assert left - right == expected
 
 
-@given(cls=st.sampled_from(tick_classes),
-       n=st.integers(-999, 999), m=st.integers(-999, 999))
+@pytest.mark.parametrize('cls', tick_classes)
+@example(n=2, m=3)
+@given(n=st.integers(-999, 999), m=st.integers(-999, 999))
 def test_tick_equality(cls, n, m):
     assume(m != n)
     # tick == tock iff tick.n == tock.n
@@ -68,6 +71,9 @@ def test_tick_equality(cls, n, m):
     assert left == right
     assert not (left != right)
 
+    if n != 0:
+        assert cls(n) != cls(-n)
+
 
 # ---------------------------------------------------------------------
 
@@ -234,21 +240,8 @@ def test_tick_zero(cls1, cls2):
 
 @pytest.mark.parametrize('cls', tick_classes)
 def test_tick_equalities(cls):
-    assert cls(3) == cls(3)
     assert cls() == cls(1)
 
-    # not equals
-    assert cls(3) != cls(2)
-    assert cls(3) != cls(-3)
-
-
-@pytest.mark.parametrize('cls', tick_classes)
-def test_tick_operators(cls):
-    assert cls(3) + cls(2) == cls(5)
-    assert cls(3) - cls(2) == cls(1)
-    assert cls(800) + cls(300) == cls(1100)
-    assert cls(1000) - cls(5) == cls(995)
-
 
 @pytest.mark.parametrize('cls', tick_classes)
 def test_tick_offset(cls):