pitrou commented on code in PR #37797:
URL: https://github.com/apache/arrow/pull/37797#discussion_r1345676663
##########
python/pyarrow/tests/test_cffi.py:
##########
@@ -411,3 +415,120 @@ def test_imported_batch_reader_error():
match="Expected to be able to read 16 bytes "
"for message body, got 8"):
reader_new.read_all()
+
+
[email protected]('obj', [pa.int32(), pa.field('foo', pa.int32()),
+ pa.schema({'foo': pa.int32()})],
+ ids=['type', 'field', 'schema'])
+def test_roundtrip_schema_capsule(obj):
+ gc.collect() # Make sure no Arrow data dangles in a ref cycle
+ old_allocated = pa.total_allocated_bytes()
+
+ capsule = obj.__arrow_c_schema__()
+ assert PyCapsule_IsValid(capsule, b"arrow_schema") == 1
+ obj_out = type(obj)._import_from_c_capsule(capsule)
+ assert obj_out == obj
+
+ assert pa.total_allocated_bytes() == old_allocated
+
+ capsule = obj.__arrow_c_schema__()
+
+ assert pa.total_allocated_bytes() > old_allocated
+ del capsule
+ assert pa.total_allocated_bytes() == old_allocated
+
+
[email protected]('arr,schema_accessor,bad_type,good_type', [
+ (pa.array(['a', 'b', 'c']), lambda x: x.type, pa.int32(), pa.string()),
+ (
+ pa.record_batch([pa.array(['a', 'b', 'c'])], names=['x']),
+ lambda x: x.schema,
+ pa.schema({'x': pa.int32()}),
+ pa.schema({'x': pa.string()})
+ ),
+], ids=['array', 'record_batch'])
+def test_roundtrip_array_capsule(arr, schema_accessor, bad_type, good_type):
+ gc.collect() # Make sure no Arrow data dangles in a ref cycle
+ old_allocated = pa.total_allocated_bytes()
+
+ import_array = type(arr)._import_from_c_capsule
+
+ schema_capsule, capsule = arr.__arrow_c_array__()
+ assert PyCapsule_IsValid(schema_capsule, b"arrow_schema") == 1
+ assert PyCapsule_IsValid(capsule, b"arrow_array") == 1
+ arr_out = import_array(schema_capsule, capsule)
+ assert arr_out.equals(arr)
+
+ assert pa.total_allocated_bytes() > old_allocated
+ del arr_out
+
+ assert pa.total_allocated_bytes() == old_allocated
+
+ capsule = arr.__arrow_c_array__()
+
+ assert pa.total_allocated_bytes() > old_allocated
+ del capsule
+ assert pa.total_allocated_bytes() == old_allocated
+
+ with pytest.raises(ValueError,
+ match=r"Could not cast.* string to requested .* int32"):
+ arr.__arrow_c_array__(bad_type.__arrow_c_schema__())
+
+ schema_capsule, array_capsule = arr.__arrow_c_array__(
+ good_type.__arrow_c_schema__())
+ arr_out = import_array(schema_capsule, array_capsule)
+ assert schema_accessor(arr_out) == good_type
+
+
+# TODO: implement requested_schema for stream
[email protected]('constructor', [
+ pa.RecordBatchReader.from_batches,
+ # Use a lambda because we need to re-order the parameters
+ lambda schema, batches: pa.Table.from_batches(batches, schema),
+], ids=['recordbatchreader', 'table'])
+def test_roundtrip_reader_capsule(constructor):
+ batches = make_batches()
+ schema = batches[0].schema
+
+ gc.collect() # Make sure no Arrow data dangles in a ref cycle
+ old_allocated = pa.total_allocated_bytes()
+
+ obj = constructor(schema, batches)
+
+ capsule = obj.__arrow_c_stream__()
+ assert PyCapsule_IsValid(capsule, b"arrow_array_stream") == 1
+ imported_reader = pa.RecordBatchReader._import_from_c_capsule(capsule)
+ assert imported_reader.schema == schema
+ for batch, expected in zip(imported_reader, batches):
Review Comment:
This won't check that the number of batches is the same on either side,
since `zip` stops when the shortest iterator is exhausted.
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