diff --git a/mcp23xxx/grouprecording_test.go b/mcp23xxx/grouprecording_test.go
new file mode 100644
index 0000000..2e813ab
--- /dev/null
+++ b/mcp23xxx/grouprecording_test.go
@@ -0,0 +1,159 @@
+// Copyright 2025 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package mcp23xxx
+
+import (
+	"periph.io/x/conn/v3/i2c/i2ctest"
+)
+
+var recordingData = map[string][]i2ctest.IO{
+	"TestGroup": {
+		{Addr: 0x20, W: []uint8{0x0}, R: []uint8{0x0}},
+		{Addr: 0x20, W: []uint8{0x0, 0x10}},
+		{Addr: 0x20, W: []uint8{0xa}, R: []uint8{0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0xa, 0x40}}},
+	"TestReadWrite": {
+		{Addr: 0x20, W: []uint8{0x0}, R: []uint8{0x10}},
+		{Addr: 0x20, W: []uint8{0xa}, R: []uint8{0x40}},
+		{Addr: 0x20, W: []uint8{0x0, 0xf0}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0x41}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x11}},
+		{Addr: 0x20, W: []uint8{0xa, 0x42}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x22}},
+		{Addr: 0x20, W: []uint8{0xa, 0x43}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x33}},
+		{Addr: 0x20, W: []uint8{0xa, 0x44}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x44}},
+		{Addr: 0x20, W: []uint8{0xa, 0x45}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x55}},
+		{Addr: 0x20, W: []uint8{0xa, 0x46}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x66}},
+		{Addr: 0x20, W: []uint8{0xa, 0x47}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x77}},
+		{Addr: 0x20, W: []uint8{0xa, 0x48}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x88}},
+		{Addr: 0x20, W: []uint8{0xa, 0x49}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x99}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4a}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xaa}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4b}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xbb}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4c}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xcc}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4d}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xdd}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4e}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xee}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xff}},
+		{Addr: 0x20, W: []uint8{0x0, 0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf}},
+		{Addr: 0x20, W: []uint8{0x0, 0xf}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0x1f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x11}},
+		{Addr: 0x20, W: []uint8{0xa, 0x2f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x22}},
+		{Addr: 0x20, W: []uint8{0xa, 0x3f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x33}},
+		{Addr: 0x20, W: []uint8{0xa, 0x4f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x44}},
+		{Addr: 0x20, W: []uint8{0xa, 0x5f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x55}},
+		{Addr: 0x20, W: []uint8{0xa, 0x6f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x66}},
+		{Addr: 0x20, W: []uint8{0xa, 0x7f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x77}},
+		{Addr: 0x20, W: []uint8{0xa, 0x8f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x88}},
+		{Addr: 0x20, W: []uint8{0xa, 0x9f}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x99}},
+		{Addr: 0x20, W: []uint8{0xa, 0xaf}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xaa}},
+		{Addr: 0x20, W: []uint8{0xa, 0xbf}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xbb}},
+		{Addr: 0x20, W: []uint8{0xa, 0xcf}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xcc}},
+		{Addr: 0x20, W: []uint8{0xa, 0xdf}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xdd}},
+		{Addr: 0x20, W: []uint8{0xa, 0xef}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xee}},
+		{Addr: 0x20, W: []uint8{0xa, 0xff}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xff}},
+		{Addr: 0x20, W: []uint8{0x0, 0xe}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfe}},
+		{Addr: 0x20, W: []uint8{0x0, 0xc}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfc}},
+		{Addr: 0x20, W: []uint8{0x0, 0x8}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf8}},
+		{Addr: 0x20, W: []uint8{0x0, 0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf0}},
+		{Addr: 0x20, W: []uint8{0x0, 0xf0}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf1}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x11}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf2}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x22}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf3}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x33}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf2}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf4}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x44}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf5}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x55}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf4}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf6}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x66}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf7}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x77}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf6}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf4}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf8}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x88}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf9}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0x99}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf8}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfa}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xaa}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfb}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xbb}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfa}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf8}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfc}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xcc}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfd}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xdd}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfc}},
+		{Addr: 0x20, W: []uint8{0xa, 0xfe}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xee}},
+		{Addr: 0x20, W: []uint8{0xa, 0xff}},
+		{Addr: 0x20, W: []uint8{0x9}, R: []uint8{0xff}},
+		{Addr: 0x20, W: []uint8{0x0, 0x0}},
+		{Addr: 0x20, W: []uint8{0xa, 0xf}},
+		{Addr: 0x20, W: []uint8{0xa, 0x0}}},
+}