TST: add nullable array frame constructor dtype tests (#37972)

Author: arw2019

pandas/tests/frame/test_constructors.py

@@ -1004,6 +1004,21 @@ def test_constructor_dtype(self, data, index, columns, dtype, expected):
         df = DataFrame(data, index, columns, dtype)
         assert df.values.dtype == expected
 
+    @pytest.mark.parametrize(
+        "data,input_dtype,expected_dtype",
+        (
+            ([True, False, None], "boolean", pd.BooleanDtype),
+            ([1.0, 2.0, None], "Float64", pd.Float64Dtype),
+            ([1, 2, None], "Int64", pd.Int64Dtype),
+            (["a", "b", "c"], "string", pd.StringDtype),
+        ),
+    )
+    def test_constructor_dtype_nullable_extension_arrays(
+        self, data, input_dtype, expected_dtype
+    ):
+        df = DataFrame({"a": data}, dtype=input_dtype)
+        assert df["a"].dtype == expected_dtype()
+
     def test_constructor_scalar_inference(self):
         data = {"int": 1, "bool": True, "float": 3.0, "complex": 4j, "object": "foo"}
         df = DataFrame(data, index=np.arange(10))