def test_a_transaction_runs_many_steps_it_wraps_and_passes_state():
step_one = MockCountingStep()
step_two = MockCountingStep()
run_transaction(steps=[step_one, step_two], starting_state=0)
assert step_one.actions_taken == ["run execute: 0"]
assert step_two.actions_taken == ["run execute: 1"]
def test_a_second_retry_can_be_run():
mock_step = MockRetryStepThatRetriesTwice()
run_transaction(steps=[mock_step], starting_state=0)
assert mock_step.actions_taken == [
"ran retry on state 0 after 1 failures",
"ran retry on state 0 after 2 failures",
]
def test_if_a_transaction_fails_all_compensations_are_applied():
step_one = MockCountingStep()
step_two = MockCountingStep()
failing_step = AlwaysFailsStep()
with pytest.raises(AlwaysFailException):
run_transaction(steps=[step_one, step_two, failing_step], starting_state=0)
assert step_one.actions_taken == ["run execute: 0", "run compensate: 1"]
assert step_two.actions_taken == ["run execute: 1", "run compensate: 2"]
def test_helper_method_runs_the_step_the_expected_number_of_times():
mock_step = RegularMockStep()
with pytest.raises(FailuresAfterRetrying) as e_info:
run_transaction(steps=[attempt_retries(mock_step, times=2)],
starting_state=0)
assert mock_step.actions_taken == ["trying", "trying", "trying"]
assert str(e_info.value) == "Failed to apply step after 3 attempts"
def test_retries_can_be_stopped_by_raising_abort_retries():
mock_step = MockRetryStepThatRetriesTwiceThenGivesUp()
with pytest.raises(FailuresAfterRetrying) as e_info:
run_transaction(steps=[mock_step], starting_state=0)
assert mock_step.actions_taken == [
"ran retry on state 0 after 1 failures",
"ran retry on state 0 after 2 failures",
]
assert str(e_info.value) == "Failed to apply step after 2 attempts"
def test_if_a_transaction_fails_later_steps_are_ignored():
step_one = MockCountingStep()
step_two = MockCountingStep()
failing_step = AlwaysFailsStep()
never_executed_step = MockCountingStep()
with pytest.raises(AlwaysFailException):
run_transaction(
steps=[step_one, step_two, failing_step, never_executed_step],
starting_state=0,
)
assert never_executed_step.actions_taken == []
def test_pairs_of_lambdas_are_turned_into_a_step():
result = run_transaction(
steps=[(lambda x: x + 1, lambda y: None), (lambda x: x + 2, lambda y: None)],
starting_state=0,
)
assert result == 3
def test_final_state_is_returned():
step_one = MockCountingStep()
step_two = MockCountingStep()
result = run_transaction(steps=[step_one, step_two], starting_state=0)
assert result == 2
def test_failures_in_compensations_are_caught_and_bundled():
def create_failure(message):
def fail(s):
raise Exception(message)
return fail
with pytest.raises(CompensationFailure) as e_info:
run_transaction(
steps=[
(lambda x: x + 1, create_failure("reverting one")),
(lambda x: x + 2, create_failure("reverting two")),
(create_failure("STOP"), lambda x: x - 3),
],
starting_state=0,
)
assert str(e_info.value) == f"Failed to apply compensation of 2 steps"
error_messages = map(lambda e: str(e), e_info.value.inner_exceptions)
assert list(error_messages) == ["reverting two", "reverting one"]
async def test_regular_transactions_can_be_async():
step_1 = MockAsyncExecuteAndCompensateStep()
with pytest.raises(AsyncStepUsedInSyncTransaction):
run_transaction(steps=[step_1], starting_state=0)
def test_a_transaction_runs_a_step_it_wraps():
mock_step = MockCountingStep()
run_transaction(steps=[mock_step], starting_state=0)
assert mock_step.actions_taken == ["run execute: 0"]
def test_single_lambdas_are_turned_into_steps():
result = run_transaction(steps=[lambda x: x + 1, lambda x: x + 2], starting_state=0)
assert result == 3
def test_exceptions_are_raised_eventually():
with pytest.raises(AlwaysFailException, match="oh no - How shocking"):
run_transaction(steps=[MockCountingStep(), AlwaysFailsStep()], starting_state=0)
def test_the_retry_is_run():
mock_step = MockRetryStep()
run_transaction(steps=[mock_step], starting_state=0)
assert mock_step.actions_taken == ["ran retry on state 0 after 1 failures"]