Eliminate intermediate buffer when writing to Python stream

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/test_io.py b/tests/test_io.py
new file mode 100644
index 0000000..4ce8eb5
--- /dev/null
+++ b/tests/test_io.py
@@ -0,0 +1,26 @@
+import pytest
+
+from pikepdf import Pdf
+from io import BytesIO
+
+
+@pytest.fixture
+def sandwich(resources):
+    # Has XMP, docinfo, <?adobe-xap-filters esc="CRLF"?>, shorthand attribute XMP
+    return Pdf.open(resources / 'sandwich.pdf')
+
+
+class LimitedBytesIO(BytesIO):
+    """Version of BytesIO that only accepts small reads/writes"""
+
+    def write(self, b):
+        amt = min(len(b), 100)
+        return super().write(b[:amt])
+
+
+def test_weird_output_stream(sandwich):
+    bio = BytesIO()
+    lbio = LimitedBytesIO()
+    sandwich.save(bio, static_id=True)
+    sandwich.save(lbio, static_id=True)
+    assert bio.getvalue() == lbio.getvalue()