Verification is the deliberate checking of generated or changed software before relying on it. The check includes whether the code is correct, fits its intended job, and is understandable enough to maintain. Generated code can be a useful starting point or learning aid, but accepting code without understanding it makes its future failures and support burden your responsibility. section 1.5.4 section 2.3.3
Treat plausible output as a hypothesis, not a finished solution. A program may compile or perform a simple action while still failing important business rules. Missing payment record types, incorrect record labels, or outdated library advice can create defects that are harder to notice than syntax errors. Check that suggestions match the required specification, the domain rules, and the versions actually in use. section 1.5.7 section 2.3.1 section 2.3.3
A practical verification workflow is:
- Read generated code until you can explain what it does, why it is structured that way, and how another developer could maintain it. section 1.5.4 section 2.3.3
- Compare its behavior and terminology with the required domain layout or business rules; domain knowledge is necessary to recognize a plausible but wrong result. section 2.3.1 section 2.5
- Make important logic testable by separating it into functions, then pass both well-formed and invalid inputs through those functions. section 2.3.1
- Use tests to drive or assess implementation, including regression-test questions about what must be checked and how others will understand it. section 2.3.3
- Independently check parsing results by hand or with another tool rather than trusting only the program’s return value. section 11.4
- Confirm that generated suggestions remain appropriate for the library or tool version in use, since stale knowledge can miss vulnerabilities or improvements. section 1.5.7
Verifying an ACH parser
An initial generated ACH parser recognizes record types 1, 6, 7, and 9, but omits types 5 and 8 and mislabels 6 and 7. A revised version includes more record handling, yet still needs review. Splitting parsing into functions such as parse_file_header, parse_batch_header, parse_entry_detail, and parse_addenda makes it possible to feed sample records and invalid data into focused tests. The improvement is not merely cleaner code: it creates places to check whether each record is classified and parsed according to the expected layout. section 2.3.1 section 2.5
Testing an IAT addenda record
A unit test can define a sample type 12 addenda record and an expected parsed result containing its record codes, originator location fields, and sequence number. Parsing logic can reject malformed city/state or country/postal-code segments, while expected record types help detect records that arrive out of sequence. This turns verification into explicit, repeatable checks rather than a visual guess that the import succeeded. section 11.4 section 11.4
Listing 11.5 Unit testing the parse routine for Type 12 addenda
class TestParsingIat712AddendaRecords:
TABLE_NAME: str = "ach_iat_addenda_712_records"
@pytest.fixture(autouse=True) #1
def setup_teardown_method(self): #1
SqlUtils.truncate_all() #1
yield #1
def test_parse_iat_addenda_712_records(self):
sample_addenda_record = "712BILBAO*BIZKAIA\ #2
➥ ES*48001\ #2
➥ 0000001" #2
record
expected_result = { #3
"record_type_code": Literal["7"], #3
"addenda_type_code": 12, #3
"originator_city": "BILBAO", #3
"originator_state": "BIZKAIA", #3
"originator_country": "ES", #3
"originator_postal_code": "48001", #3
"entry_detail_sequence_number": 1, #3
} #3
_, ach_records_type_7_id = #4
SqlUtils.setup_iat_addenda_test( #4
sample_addenda_record #4
) #4
parser = AchFileProcessor() #5
parser._parse_iat_addenda_712(ach_records_type_7_id, #5
sample_addenda_record) #5
sql = AchIat712AddendaSql() #6
retrieved_record = #6
sql.get_record(ach_records_type_7_id).model_dump( #6
exclude={"ach_records_type_7_id"} #6
) #6
assert SqlUtils.get_row_count_of_1( #7
self.TABLE_NAME #7
), f"Expected 1 row in {self.TABLE_NAME}" #7
assert ( #7
retrieved_record == expected_result #7
), f"Expected {expected_result}, #7
➥ but got {retrieved_record}" #7
Inspect the sample unit test to see verification expressed as a concrete input and an expected structured result. section 11.4
