BUG (string dtype): fix qualifier in memory usage info

pandas/core/indexes/base.py

@@ -5139,7 +5139,9 @@ def _is_memory_usage_qualified(self) -> bool:
         """
         Return a boolean if we need a qualified .info display.
         """
-        return is_object_dtype(self.dtype)
+        return is_object_dtype(self.dtype) or (
+            is_string_dtype(self.dtype) and self.dtype.storage == "python"  # type: ignore[union-attr]
+        )
 
     def __contains__(self, key: Any) -> bool:
         """

pandas/core/indexes/multi.py

@@ -66,6 +66,7 @@
     is_list_like,
     is_object_dtype,
     is_scalar,
+    is_string_dtype,
     pandas_dtype,
 )
 from pandas.core.dtypes.dtypes import (
@@ -1425,10 +1426,12 @@ def dtype(self) -> np.dtype:
     def _is_memory_usage_qualified(self) -> bool:
         """return a boolean if we need a qualified .info display"""
 
-        def f(level) -> bool:
-            return "mixed" in level or "string" in level or "unicode" in level
+        def f(dtype) -> bool:
+            return is_object_dtype(dtype) or (
+                is_string_dtype(dtype) and dtype.storage == "python"
+            )
 
-        return any(f(level.inferred_type) for level in self.levels)
+        return any(f(level.dtype) for level in self.levels)
 
     # Cannot determine type of "memory_usage"
     @doc(Index.memory_usage)  # type: ignore[has-type]

pandas/tests/frame/methods/test_info.py

@@ -7,8 +7,6 @@
 import numpy as np
 import pytest
 
-from pandas._config import using_string_dtype
-
 from pandas.compat import (
     HAS_PYARROW,
     IS64,
@@ -436,18 +434,25 @@ def test_usage_via_getsizeof():
     assert abs(diff) < 100
 
 
-@pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
-def test_info_memory_usage_qualified():
+def test_info_memory_usage_qualified(using_infer_string):
     buf = StringIO()
     df = DataFrame(1, columns=list("ab"), index=[1, 2, 3])
     df.info(buf=buf)
     assert "+" not in buf.getvalue()
 
     buf = StringIO()
-    df = DataFrame(1, columns=list("ab"), index=list("ABC"))
+    df = DataFrame(1, columns=list("ab"), index=Index(list("ABC"), dtype=object))
     df.info(buf=buf)
     assert "+" in buf.getvalue()
 
+    buf = StringIO()
+    df = DataFrame(1, columns=list("ab"), index=Index(list("ABC"), dtype="str"))
+    df.info(buf=buf)
+    if using_infer_string and HAS_PYARROW:
+        assert "+" not in buf.getvalue()
+    else:
+        assert "+" in buf.getvalue()
+
     buf = StringIO()
     df = DataFrame(
         1, columns=list("ab"), index=MultiIndex.from_product([range(3), range(3)])
@@ -460,7 +465,10 @@ def test_info_memory_usage_qualified():
         1, columns=list("ab"), index=MultiIndex.from_product([range(3), ["foo", "bar"]])
     )
     df.info(buf=buf)
-    assert "+" in buf.getvalue()
+    if using_infer_string and HAS_PYARROW:
+        assert "+" not in buf.getvalue()
+    else:
+        assert "+" in buf.getvalue()
 
 
 def test_info_memory_usage_bug_on_multiindex():
@@ -497,16 +505,15 @@ def test_info_categorical():
     df.info(buf=buf)
 
 
-@pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
 @pytest.mark.xfail(not IS64, reason="GH 36579: fail on 32-bit system")
-def test_info_int_columns():
+def test_info_int_columns(using_infer_string):
     # GH#37245
     df = DataFrame({1: [1, 2], 2: [2, 3]}, index=["A", "B"])
     buf = StringIO()
     df.info(show_counts=True, buf=buf)
     result = buf.getvalue()
     expected = textwrap.dedent(
-        """\
+        f"""\
         <class 'pandas.DataFrame'>
         Index: 2 entries, A to B
         Data columns (total 2 columns):
@@ -515,19 +522,22 @@ def test_info_int_columns():
          0   1       2 non-null      int64
          1   2       2 non-null      int64
         dtypes: int64(2)
-        memory usage: 48.0+ bytes
+        memory usage: {'50.0' if using_infer_string and HAS_PYARROW else '48.0+'} bytes
         """
     )
     assert result == expected
 
 
-@pytest.mark.xfail(using_string_dtype() and HAS_PYARROW, reason="TODO(infer_string)")
-def test_memory_usage_empty_no_warning():
+def test_memory_usage_empty_no_warning(using_infer_string):
     # GH#50066
     df = DataFrame(index=["a", "b"])
     with tm.assert_produces_warning(None):
         result = df.memory_usage()
-    expected = Series(16 if IS64 else 8, index=["Index"])
+    if using_infer_string and HAS_PYARROW:
+        value = 18
+    else:
+        value = 16 if IS64 else 8
+    expected = Series(value, index=["Index"])
     tm.assert_series_equal(result, expected)
 
 

pandas/tests/series/methods/test_info.py

@@ -7,10 +7,14 @@
 
 from pandas._config import using_string_dtype
 
-from pandas.compat import PYPY
+from pandas.compat import (
+    HAS_PYARROW,
+    PYPY,
+)
 
 from pandas import (
     CategoricalIndex,
+    Index,
     MultiIndex,
     Series,
     date_range,
@@ -41,7 +45,9 @@ def test_info_categorical():
 
 
 @pytest.mark.parametrize("verbose", [True, False])
-def test_info_series(lexsorted_two_level_string_multiindex, verbose):
+def test_info_series(
+    lexsorted_two_level_string_multiindex, verbose, using_infer_string
+):
     index = lexsorted_two_level_string_multiindex
     ser = Series(range(len(index)), index=index, name="sth")
     buf = StringIO()
@@ -63,10 +69,11 @@ def test_info_series(lexsorted_two_level_string_multiindex, verbose):
             10 non-null     int64
             """
         )
+    qualifier = "" if using_infer_string and HAS_PYARROW else "+"
     expected += textwrap.dedent(
         f"""\
         dtypes: int64(1)
-        memory usage: {ser.memory_usage()}.0+ bytes
+        memory usage: {ser.memory_usage()}.0{qualifier} bytes
         """
     )
     assert result == expected
@@ -142,14 +149,17 @@ def test_info_memory_usage_deep_pypy():
     assert s_object.memory_usage(deep=True) == s_object.memory_usage()
 
 
-@pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)", strict=False)
 @pytest.mark.parametrize(
     "index, plus",
     [
         ([1, 2, 3], False),
-        (list("ABC"), True),
+        (Index(list("ABC"), dtype="str"), not (using_string_dtype() and HAS_PYARROW)),
+        (Index(list("ABC"), dtype=object), True),
         (MultiIndex.from_product([range(3), range(3)]), False),
-        (MultiIndex.from_product([range(3), ["foo", "bar"]]), True),
+        (
+            MultiIndex.from_product([range(3), ["foo", "bar"]]),
+            not (using_string_dtype() and HAS_PYARROW),
+        ),
     ],
 )
 def test_info_memory_usage_qualified(index, plus):