Fix expanding altreps with attributes

rdata/parser/_parser.py

@@ -937,11 +937,16 @@ def parse_R_object(  # noqa: N802, C901, PLR0912, PLR0915
             )
 
             if self.expand_altrep:
+                is_object = info.object
                 info, value = self.expand_altrep_to_object(
                     info=altrep_info,
                     state=altrep_state,
                 )
-                attributes = altrep_attr
+                if altrep_attr.info.type != RObjectType.NILVALUE:
+                    info.object = is_object
+                    info.attributes = True
+                    attributes_read = True
+                    attributes = altrep_attr
             else:
                 value = (altrep_info, altrep_state, altrep_attr)
 

rdata/tests/test_rdata.py

@@ -649,14 +649,58 @@ def test_altrep_deferred_string(self) -> None:
 
     def test_altrep_wrap_real(self) -> None:
         """Test alternative representation of wrap_real."""
-        data = rdata.read_rda(
+        parsed = rdata.parser.parse_file(
             TESTDATA_PATH / "test_altrep_wrap_real.rda",
         )
+        obj = parsed.object.value[0]  # taking value as it's an rda file
+        assert obj.info.type == rdata.parser.RObjectType.REAL  # sanity check
+        assert not obj.info.object
+        assert not obj.info.attributes
+        assert obj.attributes is None
 
+        data = rdata.conversion.convert(parsed)
         np.testing.assert_equal(data, {
             "test_altrep_wrap_real": [3],
         })
 
+    def test_altrep_wrap_real_attributes(self) -> None:
+        """Test alternative representation of wrap_real with attributes."""
+        # File created in R with
+        # a = .Internal(wrap_meta(c(1, 2, 3), 0, 0)); attr(a, "foo") = "bar"; saveRDS(a, file="test_altrep_wrap_real_attributes.rds")  # noqa: E501
+        parsed = rdata.parser.parse_file(
+            TESTDATA_PATH / "test_altrep_wrap_real_attributes.rds",
+        )
+        obj = parsed.object
+        assert obj.info.type == rdata.parser.RObjectType.REAL  # sanity check
+        assert not obj.info.object
+        assert obj.info.attributes
+        assert obj.attributes is not None
+        assert obj.attributes.tag is not None
+        assert obj.attributes.tag.value.value == b"foo"
+        assert obj.attributes.value[0].value[0].value == b"bar"
+
+        data = rdata.conversion.convert(parsed)
+        np.testing.assert_equal(data, [1., 2., 3.])
+
+    def test_altrep_wrap_real_class_attribute(self) -> None:
+        """Test alternative representation of wrap_real with class attribute."""
+        # File created in R with
+        # a = .Internal(wrap_meta(c(1, 2, 3), 0, 0)); attr(a, "class") = "Date"; saveRDS(a, file="test_altrep_wrap_real_class_attribute.rds")  # noqa: E501
+        parsed = rdata.parser.parse_file(
+            TESTDATA_PATH / "test_altrep_wrap_real_class_attribute.rds",
+        )
+        obj = parsed.object
+        assert obj.info.type == rdata.parser.RObjectType.REAL  # sanity check
+        assert obj.info.object
+        assert obj.info.attributes
+        assert obj.attributes is not None
+        assert obj.attributes.tag is not None
+        assert obj.attributes.tag.value.value == b"class"
+        assert obj.attributes.value[0].value[0].value == b"Date"
+
+        data = rdata.conversion.convert(parsed)
+        np.testing.assert_equal(data, [1., 2., 3.])
+
     def test_altrep_wrap_string(self) -> None:
         """Test alternative representation of wrap_string."""
         data = rdata.read_rda(TESTDATA_PATH / "test_altrep_wrap_string.rda")