Empty preview merge fields

Verification Boundary

This suite checks the empty-field helper used by preview; it does not render a template, persist content or call a provider.

What This Suite Proves

The executable case exercises distinguish empty preview values from zero and false.

What It Does Not Prove

The suite does not establish the entire feature chain or a fresh execution result. Its retained assertions apply only within the stated dependency boundary.

Real Dependencies and Test Doubles

The empty-field calculation is real and runs only on supplied values; it uses no test doubles.

Must Not Be Doubled

The empty-field calculation must execute its real implementation.