done

lib/python3.11/site-packages/pandas/tests/extension/base/io.py

@@ -0,0 +1,39 @@
+from io import StringIO
+
+import numpy as np
+import pytest
+
+import pandas as pd
+import pandas._testing as tm
+from pandas.core.arrays import ExtensionArray
+
+
+class BaseParsingTests:
+    @pytest.mark.parametrize("engine", ["c", "python"])
+    def test_EA_types(self, engine, data, request):
+        if isinstance(data.dtype, pd.CategoricalDtype):
+            # in parsers.pyx _convert_with_dtype there is special-casing for
+            #  Categorical that pre-empts _from_sequence_of_strings
+            pass
+        elif isinstance(data.dtype, pd.core.dtypes.dtypes.NumpyEADtype):
+            # These get unwrapped internally so are treated as numpy dtypes
+            #  in the parsers.pyx code
+            pass
+        elif (
+            type(data)._from_sequence_of_strings.__func__
+            is ExtensionArray._from_sequence_of_strings.__func__
+        ):
+            # i.e. the EA hasn't overridden _from_sequence_of_strings
+            mark = pytest.mark.xfail(
+                reason="_from_sequence_of_strings not implemented",
+                raises=NotImplementedError,
+            )
+            request.node.add_marker(mark)
+
+        df = pd.DataFrame({"with_dtype": pd.Series(data, dtype=str(data.dtype))})
+        csv_output = df.to_csv(index=False, na_rep=np.nan)
+        result = pd.read_csv(
+            StringIO(csv_output), dtype={"with_dtype": str(data.dtype)}, engine=engine
+        )
+        expected = df
+        tm.assert_frame_equal(result, expected)