Validate Results

Unit ID: M10-U04 Estimated active time: 45-60 minutes

Validation answers whether the output follows the stated contract.

Check:

• raw source bytes and checksum remain unchanged;
• clean plus rejected row counts reconcile with raw rows;
• keys are present and unique where required;
• output columns and dtypes match the dictionary;
• numeric values remain inside the approved range;
• categories come from the allowed set;
• missingness follows the pathway rule;
• joins preserve intended rows and expose unmatched keys; and
• exported files reload with the same required values.

Assertions should name the failed rule. Do not use one vague assert all_checks when a learner needs to locate the cause.