Repository: pandas-dev/pandas

Issue:
Fix mypy errors for pandas\tests\*
For a full list, expand details.

<details>

```
pandas\tests\tseries\offsets\test_offsets_properties.py:54: error: Argument "min_value" to "datetimes" has incompatible type "Tuple[Any]"; expected "datetime"
pandas\tests\tseries\offsets\test_offsets_properties.py:54: error: Argument "max_value" to "datetimes" has incompatible type "Tuple[Any]"; expected "datetime"
pandas\tests\io\parser\conftest.py:11: error: Need type annotation for 'float_precision_choices' (hint: "float_precision_choices: List[<type>] = ...")
pandas\tests\io\parser\conftest.py:29: error: Incompatible types in assignment (expression has type "str", base class "BaseParser" defined the type as "None")
pandas\tests\io\parser\conftest.py:42: error: Incompatible types in assignment (expression has type "str", base class "BaseParser" defined the type as "None")
pandas\tests\io\parser\conftest.py:62: error: Unsupported operand types for + ("List[CParser]" and "List[PythonParser]")
pandas\tests\extension\json\array.py:30: error: Need type annotation for 'na_value'
pandas\conftest.py:11: error: Module 'pytz' has no attribute 'FixedOffset'
pandas\conftest.py:486: error: Unsupported operand types for + ("List[str]" and "List[object]")
pandas\conftest.py:500: error: Unsupported operand types for + ("List[object]" and "List[str]")
pandas\conftest.py:505: error: Unsupported operand types for + ("List[object]" and "List[str]")
pandas\conftest.py:506: error: Unsupported operand types for + ("List[object]" and "List[str]")
pandas\tests\test_base.py:1312: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\test_base.py:1354: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\test_algos.py:770: error: Invalid signature "def (self: Any) -> Any"
pandas\tests\tseries\offsets\test_offsets.py:662: error: Incompatible types in assignment (expression has type "Type[BusinessDay]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:757: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[BusinessDay, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:784: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[BusinessDay, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:849: error: Incompatible types in assignment (expression has type "Type[BusinessHour]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:2255: error: Incompatible types in assignment (expression has type "Type[CustomBusinessHour]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:2547: error: Incompatible types in assignment (expression has type "Type[CustomBusinessDay]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:2645: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessDay, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:2672: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessDay, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:2826: error: Incompatible types in assignment (expression has type "Type[CustomBusinessMonthEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:2889: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessMonthEnd, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:2909: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessMonthEnd, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:2975: error: Incompatible types in assignment (expression has type "Type[CustomBusinessMonthBegin]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3038: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessMonthBegin, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:3058: error: Argument 1 to "append" of "list" has incompatible type "Tuple[int, Dict[datetime, datetime]]"; expected "Tuple[CustomBusinessMonthBegin, Dict[datetime, datetime]]"
pandas\tests\tseries\offsets\test_offsets.py:3123: error: Incompatible types in assignment (expression has type "Type[Week]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3125: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3126: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3222: error: Incompatible types in assignment (expression has type "Type[WeekOfMonth]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3223: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3224: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3322: error: Incompatible types in assignment (expression has type "Type[LastWeekOfMonth]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3323: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3324: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3399: error: Incompatible types in assignment (expression has type "Type[SemiMonthEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3400: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3401: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3658: error: Incompatible types in assignment (expression has type "Type[SemiMonthBegin]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_offsets.py:3659: error: Cannot determine type of '_offset'
pandas\tests\tseries\offsets\test_offsets.py:3660: error: Cannot determine type of '_offset'
pandas\tests\series\test_constructors.py:48: error: Need type annotation for 'x'
pandas\tests\series\test_constructors.py:53: error: Need type annotation for 'x'
pandas\tests\plotting\test_backend.py:12: error: Module has no attribute "plot"
pandas\tests\io\test_sql.py:964: error: Incompatible types in assignment (expression has type "str", base class "_TestSQLApi" defined the type as "None")
pandas\tests\io\test_sql.py:1156: error: Incompatible types in assignment (expression has type "str", base class "_TestSQLApi" defined the type as "None")
pandas\tests\io\test_sql.py:2075: error: Definition of "flavor" in base class "_TestMySQLAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\test_sql.py:2081: error: Definition of "flavor" in base class "_TestMySQLAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\test_sql.py:2087: error: Definition of "flavor" in base class "_TestPostgreSQLAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\test_sql.py:2093: error: Definition of "flavor" in base class "_TestPostgreSQLAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\test_sql.py:2098: error: Definition of "flavor" in base class "_TestSQLiteAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\test_sql.py:2103: error: Definition of "flavor" in base class "_TestSQLiteAlchemy" is incompatible with definition in base class "_TestSQLAlchemy"
pandas\tests\io\json\test_ujson.py:4: error: Name 'json' already defined (by an import)
pandas\tests\indexing\test_coercion.py:933: error: List item 0 has incompatible type "int"; expected "str"
pandas\tests\indexing\test_coercion.py:933: error: List item 1 has incompatible type "int"; expected "str"
pandas\tests\indexing\test_coercion.py:934: error: List item 0 has incompatible type "float"; expected "str"
pandas\tests\indexing\test_coercion.py:934: error: List item 1 has incompatible type "float"; expected "str"
pandas\tests\indexing\test_coercion.py:935: error: List item 0 has incompatible type "complex"; expected "str"
pandas\tests\indexing\test_coercion.py:935: error: List item 1 has incompatible type "complex"; expected "str"
pandas\tests\indexing\test_coercion.py:936: error: List item 0 has incompatible type "bool"; expected "str"
pandas\tests\indexing\test_coercion.py:936: error: List item 1 has incompatible type "bool"; expected "str"
pandas\tests\indexes\interval\test_interval_tree.py:157: error: Argument 1 to "map" has incompatible type "Type[List[Any]]"; expected "Callable[[Tuple[int, ...]], List[_T]]"
pandas\tests\indexes\interval\test_interval_tree.py:164: error: Argument 1 to "map" has incompatible type "Type[List[Any]]"; expected "Callable[[Tuple[int, ...]], List[_T]]"
pandas\tests\frame\test_constructors.py:53: error: Need type annotation for 'x'
pandas\tests\frame\test_constructors.py:59: error: Need type annotation for 'x'
pandas\tests\frame\test_constructors.py:75: error: Need type annotation for 'x'
pandas\tests\dtypes\test_inference.py:78: error: Need type annotation for 'x'
pandas\tests\dtypes\test_inference.py:291: error: Too many arguments for "tuple"
pandas\tests\dtypes\test_inference.py:291: error: Argument 1 to "tuple" has incompatible type "int"; expected "Iterable[Any]"
pandas\tests\computation\test_eval.py:1883: error: Dict entry 1 has incompatible type "str": "Type[ExprVisitor]"; expected "str": "Type[BaseExprVisitor]"
pandas\tests\arrays\test_period.py:245: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\arrays\test_datetimelike.py:225: error: Incompatible types in assignment (expression has type "Type[DatetimeIndex]", base class "SharedTests" defined the type as "None")
pandas\tests\arrays\test_datetimelike.py:476: error: Incompatible types in assignment (expression has type "Type[TimedeltaIndex]", base class "SharedTests" defined the type as "None")
pandas\tests\arrays\test_datetimelike.py:586: error: Incompatible types in assignment (expression has type "Type[PeriodIndex]", base class "SharedTests" defined the type as "None")
pandas\tests\arithmetic\test_datetime64.py:2164: error: "DatetimeIndex" has no attribute "tz_localize"
pandas\tests\tseries\offsets\test_yqm_offsets.py:545: error: Incompatible types in assignment (expression has type "Type[QuarterEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:692: error: Incompatible types in assignment (expression has type "Type[BQuarterBegin]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:817: error: Incompatible types in assignment (expression has type "Type[BQuarterEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:964: error: Incompatible types in assignment (expression has type "Type[YearBegin]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:1118: error: Incompatible types in assignment (expression has type "Type[YearEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:1267: error: Incompatible types in assignment (expression has type "Type[BYearBegin]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:1340: error: Incompatible types in assignment (expression has type "Type[BYearEnd]", base class "Base" defined the type as "None")
pandas\tests\tseries\offsets\test_yqm_offsets.py:1413: error: Incompatible types in assignment (expression has type "Type[BYearEnd]", base class "Base" defined the type as "None")
pandas\tests\series\test_operators.py:787: error: "Type[Series]" has no attribute "div"
pandas\tests\series\test_operators.py:787: error: "Type[Series]" has no attribute "rdiv"
pandas\tests\indexing\test_loc.py:819: error: No overload variant of "slice" matches argument types "None", "str", "None"
pandas\tests\indexing\test_loc.py:819: note: Possible overload variant:
pandas\tests\indexing\test_loc.py:819: note:     def __init__(self, start: Optional[int], stop: Optional[int], step: Optional[int] = ...) -> slice
pandas\tests\indexing\test_loc.py:819: note:     <1 more non-matching overload not shown>
pandas\tests\indexes\test_numeric.py:99: error: Incompatible types in assignment (expression has type "Type[Float64Index]", base class "Base" defined the type as "None")
pandas\tests\indexes\test_numeric.py:605: error: Incompatible types in assignment (expression has type "Type[Int64Index]", base class "Base" defined the type as "None")
pandas\tests\indexes\test_numeric.py:889: error: Incompatible types in assignment (expression has type "Type[UInt64Index]", base class "Base" defined the type as "None")
pandas\tests\indexes\test_category.py:20: error: Incompatible types in assignment (expression has type "Type[CategoricalIndex]", base class "Base" defined the type as "None")
pandas\tests\indexes\test_base.py:49: error: Incompatible types in assignment (expression has type "Type[Index]", base class "Base" defined the type as "None")
pandas\tests\indexes\test_base.py:526: error: Need type annotation for 'x'
pandas\tests\indexes\test_base.py:549: error: Need type annotation for 'x'
pandas\tests\indexes\test_base.py:1743: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1744: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1745: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1746: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1747: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1748: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1750: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1751: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1752: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1753: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1754: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1755: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1756: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1757: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:1758: error: Slice index must be an integer or None
pandas\tests\indexes\test_base.py:2438: error: Incompatible types in assignment (expression has type "Type[Index]", base class "Base" defined the type as "None")
pandas\tests\indexes\interval\test_base.py:15: error: Incompatible types in assignment (expression has type "Type[IntervalIndex]", base class "Base" defined the type as "None")
pandas\tests\frame\test_convert_to.py:579: error: Argument 1 to "defaultdict" has incompatible type "Type[List[Any]]"; expected "Optional[Callable[[], Dict[str, float]]]"
pandas\tests\dtypes\test_common.py:327: error: Unsupported operand types for + ("List[Series]" and "List[str]")
pandas\tests\dtypes\test_common.py:355: error: Unsupported operand types for + ("List[Series]" and "List[object]")
pandas\tests\dtypes\test_common.py:387: error: Unsupported operand types for + ("List[Series]" and "List[str]")
pandas\tests\api\test_api.py:44: error: Need type annotation for 'deprecated_modules' (hint: "deprecated_modules: List[<type>] = ...")
pandas\tests\api\test_api.py:95: error: Need type annotation for 'deprecated_classes' (hint: "deprecated_classes: List[<type>] = ...")
pandas\tests\api\test_api.py:98: error: Need type annotation for 'deprecated_classes_in_future' (hint: "deprecated_classes_in_future: List[<type>] = ...")
pandas\tests\api\test_api.py:174: error: Need type annotation for 'deprecated_funcs_in_future' (hint: "deprecated_funcs_in_future: List[<type>] = ...")
pandas\tests\api\test_api.py:177: error: Need type annotation for 'deprecated_funcs' (hint: "deprecated_funcs: List[<type>] = ...")
pandas\tests\indexes\test_range.py:22: error: Incompatible types in assignment (expression has type "Type[RangeIndex]", base class "Base" defined the type as "None")
pandas\tests\indexes\timedeltas\test_timedelta.py:31: error: Incompatible types in assignment (expression has type "Type[TimedeltaIndex]", base class "Base" defined the type as "None")
pandas\tests\indexes\period\test_period.py:26: error: Incompatible types in assignment (expression has type "Type[PeriodIndex]", base class "Base" defined the type as "None")
pandas\tests\indexes\datetimes\test_datetimelike.py:10: error: Incompatible types in assignment (expression has type "Type[DatetimeIndex]", base class "Base" defined the type as "None")
pandas\tests\arrays\test_array.py:36: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\arrays\test_array.py:42: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\arrays\test_array.py:128: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\arrays\test_array.py:163: error: Argument "freq" to "period_array" has incompatible type "str"; expected "Optional[Tick]"
pandas\tests\extension\test_sparse.py:311: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_sparse.py:312: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_sparse.py:313: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_sparse.py:314: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_numpy.py:252: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_numpy.py:253: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_numpy.py:254: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\test_numpy.py:255: error: Incompatible types in assignment (expression has type "None", base class "BaseArithmeticOpsTests" defined the type as "Type[TypeError]")
pandas\tests\extension\json\test_json.py:118: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:118: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:122: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:122: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:145: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:145: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:152: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:152: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:168: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:168: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:172: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:172: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:192: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:192: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:248: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:248: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:261: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:261: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:289: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:289: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:307: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:307: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:311: error: Definition of "assert_series_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\json\test_json.py:311: error: Definition of "assert_frame_equal" in base class "BaseJSON" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:113: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:113: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:118: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:118: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:122: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:122: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:129: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:129: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:133: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:133: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:141: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:141: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:166: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:166: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:182: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:182: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:186: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:186: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:194: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:194: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:198: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:198: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:267: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:267: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:301: error: Definition of "assert_series_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
pandas\tests\extension\decimal\test_decimal.py:301: error: Definition of "assert_frame_equal" in base class "BaseDecimal" is incompatible with definition in base class "BaseExtensionTests"
(pandas-dev) 
```

</details>

This breaks down to the following number of errors in relevant modules:


- [x]      29 pandas\tests\tseries\offsets\test_offsets.py #29340
- [x]      26 pandas\tests\extension\decimal\test_decimal.py #31730
- [x]      24 pandas\tests\extension\json\test_json.py #31836
- [x]      19 pandas\tests\indexes\test_base.py #29188
- [x]       8 pandas\tests\tseries\offsets\test_yqm_offsets.py #28996
- [x]       8 pandas\tests\io\test_sql.py #29006
- [x]       8 pandas\tests\indexing\test_coercion.py #28990
- [x]       5 pandas\tests\api\test_api.py #28935
- [ ]       5 pandas\conftest.py #29046
- [x]       4 pandas\tests\io\parser\conftest.py #28973
- [x]       4 pandas\tests\extension\test_sparse.py #28947
- [x]       4 pandas\tests\extension\test_numpy.py #28947
- [x]       4 pandas\tests\arrays\test_array.py #28970
- [x]       3 pandas\tests\indexes\test_numeric.py #28961
- [x]       3 pandas\tests\frame\test_constructors.py #29115
- [x]       3 pandas\tests\dtypes\test_inference.py #29114
- [x]       3 pandas\tests\dtypes\test_common.py #29179
- [x]       3 pandas\tests\arrays\test_datetimelike.py #29014
- [x]       2 pandas\tests\tseries\offsets\test_offsets_properties.py #28972
- [x]       2 pandas\tests\test_base.py #28970
- [x]       2 pandas\tests\series\test_operators.py #29826
- [x]       2 pandas\tests\series\test_constructors.py #29108
- [x]       2 pandas\tests\indexes\interval\test_interval_tree.py #29021
- [x]       1 pandas\tests\test_algos.py #28960
- [x]       1 pandas\tests\plotting\test_backend.py #29016
- [x]       1 pandas\tests\io\json\test_ujson.py #29022
- [x]       ~~1 pandas\tests\indexing\test_loc.py~~
- [x]       1 pandas\tests\indexes\timedeltas\test_timedelta.py #28961
- [x]       1 pandas\tests\indexes\test_range.py #28961
- [x]       1 pandas\tests\indexes\test_category.py #28961
- [x]       1 pandas\tests\indexes\period\test_period.py #28961
- [x]       1 pandas\tests\indexes\interval\test_base.py #28961
- [x]       1 pandas\tests\indexes\datetimes\test_datetimelike.py #28961
- [x]       1 pandas\tests\frame\test_convert_to.py #28965
- [x]       1 pandas\tests\extension\json\array.py #31718
- [x]       1 pandas\tests\computation\test_eval.py #29007
- [x]       1 pandas\tests\arrays\test_period.py #28970
- [ ]       1 pandas\tests\arithmetic\test_datetime64.py #31716

assume that the degree of difficulty to resolve will vary, but some should be good first issues.

PRs to tackle individual modules preferred and remove from whitelist in setup.cfg.


Discussion:
✋ I'd like to work on this! I can take the mypy errors in `pandas\conftest.py`. 
I would like to work on \api\test_api.py.
I would like to work on \extension\test_numpy.py to get started. Will be my first pull request.
working on 
pandas\tests\arrays\test_array.py

for this i changed pandas/core/arrays/period.py
 freq: Optional[Tick]  => freq: Optional[Union[str, Tick]] .
Is this  correct approach to resolve this.
Also one more option "offset" is possible.Test cases are not using  offset object in freq so Union[str, Tick] is not giving any mypy issue.


Resolving patch:
diff --git a/pandas/core/arrays/period.py b/pandas/core/arrays/period.py
--- a/pandas/core/arrays/period.py
+++ b/pandas/core/arrays/period.py
@@ -831,7 +831,9 @@ def _raise_on_incompatible(left, right):
 
 
 def period_array(
-    data: Sequence[Optional[Period]], freq: Optional[Tick] = None, copy: bool = False
+    data: Sequence[Optional[Period]],
+    freq: Optional[Union[str, Tick]] = None,
+    copy: bool = False,
 ) -> PeriodArray:
     """
     Construct a new PeriodArray from a sequence of Period scalars.


Test patch: