tests/extmod: Use bytearray instead of bytes for uctypes test.

Because the test modifies the (now) bytearray object, and if it's a bytes
object it's not guaranteed that it can be modified, or that this constant
object isn't used elsewhere.

Signed-off-by: Damien George <damien@micropython.org>

tests/extmod/uctypes_32bit_intbig.py

@@ -6,7 +6,7 @@ except ImportError:
     print("SKIP")
     raise SystemExit
 
-buf = b"12345678abcd"
+buf = bytearray(b"12345678abcd")
 struct = uctypes.struct(
     uctypes.addressof(buf),
     {"f32": uctypes.UINT32 | 0, "f64": uctypes.UINT64 | 4},
@@ -30,7 +30,7 @@ print(buf)
 
 print("=")
 
-buf = b"12345678abcd"
+buf = bytearray(b"12345678abcd")
 struct = uctypes.struct(
     uctypes.addressof(buf),
     {"f32": uctypes.UINT32 | 0, "f64": uctypes.UINT64 | 4},

tests/extmod/uctypes_32bit_intbig.py.exp

@@ -1,11 +1,11 @@
-b'\xff\xff\xff\x7f5678abcd'
-b'\x00\x00\x00\x805678abcd'
-b'\x03\x02\x01\xff5678abcd'
-b'\x03\x02\x01\xff\x00\x00\x00\x80\x00\x00\x00\x00'
-b'\x03\x02\x01\xff\x00\x00\x00\x00\x01\x00\x00\x00'
+bytearray(b'\xff\xff\xff\x7f5678abcd')
+bytearray(b'\x00\x00\x00\x805678abcd')
+bytearray(b'\x03\x02\x01\xff5678abcd')
+bytearray(b'\x03\x02\x01\xff\x00\x00\x00\x80\x00\x00\x00\x00')
+bytearray(b'\x03\x02\x01\xff\x00\x00\x00\x00\x01\x00\x00\x00')
 =
-b'\x7f\xff\xff\xff5678abcd'
-b'\x80\x00\x00\x005678abcd'
-b'\xff\x01\x02\x035678abcd'
-b'\xff\x01\x02\x03\x00\x00\x00\x00\x80\x00\x00\x00'
-b'\xff\x01\x02\x03\x00\x00\x00\x01\x00\x00\x00\x00'
+bytearray(b'\x7f\xff\xff\xff5678abcd')
+bytearray(b'\x80\x00\x00\x005678abcd')
+bytearray(b'\xff\x01\x02\x035678abcd')
+bytearray(b'\xff\x01\x02\x03\x00\x00\x00\x00\x80\x00\x00\x00')
+bytearray(b'\xff\x01\x02\x03\x00\x00\x00\x01\x00\x00\x00\x00')