def main():
alice = ContactTracer()
bob = ContactTracer()
### Interaction ###
process_single_day(alice, bob)
process_single_day(alice, bob)
# Compute interaction time and process another day
interaction_time = datetime.fromtimestamp(alice.start_of_today)
interaction_time += timedelta(hours=10)
process_single_day(alice, bob, interaction_time)
print("... skipping 3 days ...\n")
for _ in range(4):
alice.next_day()
bob.next_day()
### Diagnosis and reporting ###
report_day(alice.start_of_today)
print("Bob is diagnosed with SARS-CoV-2")
bob_contagious_start = datetime.fromtimestamp(bob.start_of_today - 7 * 86400)
print(
"Doctor establishes that Bob started being contagious at {}".format(
bob_contagious_start
)
)
print("\n[Bob -> Server] Bob sends:")
tracing_info_bob = bob.get_tracing_information(bob_contagious_start)
bob_contagious_start_epoch, bob_contagious_key = tracing_info_bob
print(" * his key on {}: {}".format(bob_contagious_start, bob_contagious_key.hex()))
print(
" * the corresponding start time in epoch-seconds: {}\n".format(
bob_contagious_start_epoch
)
)
### Contact tracing ###
print("[Server] Compiles download batch\n")
release_time = bob.start_of_today + 4 * SECONDS_PER_BATCH
batch = TracingDataBatch([tracing_info_bob], release_time=release_time)
print("[Server -> Alice] Alice receives batch")
print(" * Alice checks if she was in contact with an infected person")
if alice.matches_with_batch(batch) > 0:
print(" * CORRECT: Alice's phone concludes she is at risk")
else:
print(" * ERROR: Alice's phone does not conclude she is at risk")
print("\n[Alice] Runs housekeeping to update her observation store")
alice.housekeeping_after_batch(batch)
def test_observation_granularity_after_update():
ct = ContactTracer(start_time=START_TIME)
t1 = START_TIME + timedelta(minutes=20)
t2 = START_TIME + timedelta(hours=6)
t3 = START_TIME + timedelta(days=1, hours=6)
ct.add_observation(EPHID1, t1)
ct.add_observation(EPHID2, t2)
ct.next_day()
ct.add_observation(EPHID2, t3)
t4 = int((START_TIME + timedelta(days=1, hours=10)).timestamp())
release_time = (t4 // SECONDS_PER_BATCH) * SECONDS_PER_BATCH
batch = TracingDataBatch([], release_time=release_time)
ct.housekeeping_after_batch(batch)
# All observations should now be at day granularity
for time in ct.observations:
assert time % config.SECONDS_PER_DAY == 0
def test_tracing_batch_init():
batch = TracingDataBatch([])
# Approximate test for default release time
assert datetime.now().timestamp(
) - batch.release_time < SECONDS_PER_BATCH + 60
def test_tracing_batch_aligned_release_time():
# With an aligned release time we shouldn't get an error
ts_start = int(START_TIME.timestamp())
release_time = (ts_start // SECONDS_PER_BATCH) * SECONDS_PER_BATCH
TracingDataBatch([], release_time=release_time)
def test_tracing_batch_non_aligned_release_time():
# Don't accept release time that does not align to batch boundary
release_time = int(START_TIME.timestamp())
with pytest.raises(ValueError):
TracingDataBatch([], release_time=release_time)