Common Return Code Bugs in Function Testing and Their Solutions

This article discusses two common bugs related to function return codes encountered during white‑box testing, explains why they occur, and provides concrete remediation steps.

Return Code Bug 1 : In an exceptional scenario the function returns the success code QCONF_OK because the variable ret is initialized to QCONF_OK and never updated when an error occurs, causing the caller to treat the error as a normal flow.

Solution : Assign a distinct return value for each error branch so the caller can differentiate success from failure.

Return Code Bug 2 : The caller checks for -1 to detect failure, but the callee never returns -1 (it uses macros for all error codes), making the failure‑handling block unreachable.

Solution : Change the condition to if (QCONF_OK != ret) or use a unified macro for all non‑normal return codes.

Summary of Recommendations :

Check Rule

Typical Bug Points

Advice

Ensure every branch returns the correct code.

Missing assignment to the return‑code variable in complex branches.

Standardize initialization and assign a value in each error path.

Caller handling.

Make sure the callee defines all error paths and uses macros instead of raw numbers; update caller checks when return codes change.