def test_observation_granularity():
ct = ContactTracer(start_time=START_TIME)
t1 = START_TIME + timedelta(minutes=20)
t2 = START_TIME + timedelta(hours=6)
ct.add_observation(EPHID1, t1)
ct.add_observation(EPHID2, t2)
# Verify that internal representation has batch granularity
for time in ct.observations:
assert time % SECONDS_PER_BATCH == 0
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_contact_tracing_retention():
ct = ContactTracer(start_time=START_TIME)
t1 = START_TIME + timedelta(minutes=20)
t2 = START_TIME + timedelta(hours=6)
ct.add_observation(EPHID1, t1)
ct.add_observation(EPHID2, t2)
recorded_times = ct.observations.keys()
for _ in range(config.RETENTION_PERIOD + 1):
ct.next_day()
for time in recorded_times:
assert time not in ct.observations
def test_deleting_old_keys():
ct = ContactTracer(start_time=START_TIME)
ct.next_day()
ct.next_day()
assert len(ct.past_keys) > 0
old_day_key = ct.current_day_key
old_ephids = set(ct.current_ephids)
# Get with side-effects: deleting old keys
ct.get_tracing_information(START_TIME)
# Should delete all old keys
assert len(ct.past_keys) == 0
# Should pick a new day key
assert ct.current_day_key != old_day_key
# And all EphIDs should have been regenerated
assert len(set(ct.current_ephids).intersection(old_ephids)) == 0
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)