Fix to_dict and from_dict type stubs (#39)

* Update frame.pyi

* - Added tests for both from_dict and to_dict

* Added types to from_dict

* Fix failing tests

* Fix formatting

Author: KianShah

pandas-stubs/core/frame.pyi

@@ -206,7 +206,13 @@ class DataFrame(NDFrame, OpsMixin):
     def __matmul__(self, other): ...
     def __rmatmul__(self, other): ...
     @classmethod
-    def from_dict(cls, data, orient=..., dtype=..., columns=...) -> DataFrame: ...
+    def from_dict(
+        cls,
+        data: Dict[Any, Any],
+        orient: Literal["columns", "index", "tight"] = ...,
+        dtype: _str = ...,
+        columns: List[_str] = ...,
+    ) -> DataFrame: ...
     def to_numpy(
         self,
         dtype: Optional[Union[Type[DtypeNp], Dtype]] = ...,
@@ -222,7 +228,7 @@ class DataFrame(NDFrame, OpsMixin):
     @overload
     def to_dict(
         self,
-        orient: Literal["dict", "list", "series", "split", "index"] = ...,
+        orient: Literal["dict", "list", "series", "split", "tight", "index"] = ...,
         into: Hashable = ...,
     ) -> Dict[_str, Any]: ...
     def to_gbq(

tests/test_frame.py

@@ -774,6 +774,19 @@ def test_types_resample() -> None:
     df.resample("20min", origin="epoch", offset=pd.Timedelta(2, "minutes"), on="date")
 
 
+def test_types_to_dict() -> None:
+    data = pd.DataFrame({"a": [1], "b": [2]})
+    data.to_dict(orient="records")
+    data.to_dict(orient="dict")
+    data.to_dict(orient="list")
+    data.to_dict(orient="series")
+    data.to_dict(orient="split")
+    data.to_dict(orient="index")
+
+    # orient param accepting "tight" added in 1.4.0 https://pandas.pydata.org/docs/whatsnew/v1.4.0.html
+    data.to_dict(orient="tight")
+
+
 def test_types_from_dict() -> None:
     pd.DataFrame.from_dict({"col_1": [3, 2, 1, 0], "col_2": ["a", "b", "c", "d"]})
     pd.DataFrame.from_dict({1: [3, 2, 1, 0], 2: ["a", "b", "c", "d"]})
@@ -783,6 +796,17 @@ def test_types_from_dict() -> None:
     pd.DataFrame.from_dict(
         data={"col_1": {"a": 1}, "col_2": {"a": 1, "b": 2}}, orient="columns"
     )
+    # orient param accepting "tight" added in 1.4.0 https://pandas.pydata.org/docs/whatsnew/v1.4.0.html
+    pd.DataFrame.from_dict(
+        data={
+            "index": [("a", "b"), ("a", "c")],
+            "columns": [("x", 1), ("y", 2)],
+            "data": [[1, 3], [2, 4]],
+            "index_names": ["n1", "n2"],
+            "column_names": ["z1", "z2"],
+        },
+        orient="tight",
+    )
 
 
 def test_pipe() -> None: