circuitpython/tests/basics/memoryview_gc.py

# test memoryview retains pointer to original object/buffer
try:
    memoryview
except:
    print("SKIP")
    raise SystemExit

b = bytearray(10)
m = memoryview(b)[1:]
for i in range(len(m)):
    m[i] = i

# reclaim b, but hopefully not the buffer
b = None
import gc
gc.collect()

# allocate lots of memory
for i in range(100000):
    [42, 42, 42, 42]

# check that the memoryview is still what we want
print(list(m))

# check that creating a memoryview of a memoryview retains the underlying data
m = None
gc.collect()  # cleanup from previous test
m = memoryview(memoryview(bytearray(i for i in range(50)))[5:-5])
print(sum(m), list(m[:10]))
gc.collect()
for i in range(10):
    list(range(10))  # allocate memory to overwrite any reclaimed heap
print(sum(m), list(m[:10]))