assert¶

Validate a boolean quality condition across all rows without changing the active dataset.

Syntax¶

assert <boolean-expression>

True rows pass. False or missing predicate results fail. An empty dataset passes. A successful check prints assertion passed: N rows; a failure reports checked and failed row counts and preserves the active relation.

Examples¶

assert age >= 0
assert bmi == null
assert lower(sex) != "unknown"

The expression uses TabDat's existing identifiers, operators, functions, and explicit-null semantics. Options, if clauses, assignment, row filtering, and row-level diagnostics are not part of this bounded command. Aggregate scans preserve Polars-lazy execution.