support for readonly buffers (#863) (#1466)

tests/test_buffers.py

@@ -1,8 +1,14 @@
+import io
 import struct
+import sys
+
 import pytest
+
 from pybind11_tests import buffers as m
 from pybind11_tests import ConstructorStats
 
+PY3 = sys.version_info[0] >= 3
+
 pytestmark = pytest.requires_numpy
 
 with pytest.suppress(ImportError):
@@ -85,3 +91,28 @@ def test_pointer_to_member_fn():
         buf.value = 0x12345678
         value = struct.unpack('i', bytearray(buf))[0]
         assert value == 0x12345678
+
+
+@pytest.unsupported_on_pypy
+def test_readonly_buffer():
+    buf = m.BufferReadOnly(0x64)
+    view = memoryview(buf)
+    assert view[0] == 0x64 if PY3 else b'd'
+    assert view.readonly
+
+
+@pytest.unsupported_on_pypy
+def test_selective_readonly_buffer():
+    buf = m.BufferReadOnlySelect()
+
+    memoryview(buf)[0] = 0x64 if PY3 else b'd'
+    assert buf.value == 0x64
+
+    io.BytesIO(b'A').readinto(buf)
+    assert buf.value == ord(b'A')
+
+    buf.readonly = True
+    with pytest.raises(TypeError):
+        memoryview(buf)[0] = 0 if PY3 else b'\0'
+    with pytest.raises(TypeError):
+        io.BytesIO(b'1').readinto(buf)