Fix WeekOfMonth constructor (#699)

* Fix WeekOfMonth constructor

* check+assert_type

Author: twoertwein

pandas-stubs/_libs/tslibs/offsets.pyi

@@ -178,7 +178,11 @@ class Week(SingleConstructorOffset):
         self, n: int = ..., normalize: bool = ..., weekday: int | None = ...
     ) -> None: ...
 
-class WeekOfMonth(WeekOfMonthMixin): ...
+class WeekOfMonth(WeekOfMonthMixin):
+    def __init__(
+        self, n: int = ..., normalize: bool = ..., week: int = ..., weekday: int = ...
+    ) -> None: ...
+
 class LastWeekOfMonth(WeekOfMonthMixin): ...
 
 class FY5253Mixin(SingleConstructorOffset):
@@ -264,9 +268,6 @@ CDay = CustomBusinessDay
 def roll_qtrday(
     other: datetime, n: int, month: int, day_opt: str, modby: int
 ) -> int: ...
-
-INVALID_FREQ_ERR_MSG: Literal["Invalid frequency: {0}"]
-
 def shift_months(
     dtindex: npt.NDArray[np.int64], months: int, day_opt: str | None = ...
 ) -> npt.NDArray[np.int64]: ...

tests/test_timefuncs.py

@@ -635,7 +635,7 @@ def test_some_offsets() -> None:
         pd.DatetimeIndex,
     )
     # GH 320
-    tswm1 = pd.Timestamp("9/23/2022") + pd.offsets.WeekOfMonth(2, 3)
+    tswm1 = pd.Timestamp("9/23/2022") + pd.offsets.WeekOfMonth(2, True)
     check(assert_type(tswm1, pd.Timestamp), pd.Timestamp)
     tswm2 = pd.Timestamp("9/23/2022") + pd.offsets.LastWeekOfMonth(2, 3)
     check(assert_type(tswm2, pd.Timestamp), pd.Timestamp)
@@ -1141,3 +1141,14 @@ def test_timestamp_strptime_fails():
                 "%Y-%M-%D",  # type: ignore[arg-type] # pyright: ignore[reportGeneralTypeIssues]
             )
         )
+
+
+def test_weekofmonth_init():
+    # GH 629
+    check(
+        assert_type(
+            pd.offsets.WeekOfMonth(n=1, week=1, weekday=1, normalize=True),
+            pd.offsets.WeekOfMonth,
+        ),
+        pd.offsets.WeekOfMonth,
+    )