#Testing
Passing the Sandbox Doesn't Mean It Works — 7 False Signals
The automated ordering system I wrote passed every command in a provider's sandbox, but almost everything the sandbox told me differed from reality, from response times and charges to accepted names and items that were created successfully but could not be found. Here are 7 false signals and how to write code that does not fall for them.
Cross-Model Audits of AI-Written Code — Process, Not Faith
After using AI to port a calculator from a 35-sheet engineering spreadsheet, how do I know it is correct? This article covers three independent audit rounds by an agent from another provider, the rules to set before starting, confidence levels that keep claims within the evidence, and the classes of errors AI kept making in every round.
Bank Open API QR Payments — From Sandbox to Status Lifecycle
A static PromptPay QR is easy to build yourself, but nothing tells you whether the customer has paid. This article walks through a bank's Open API sandbox, from requesting a token and issuing a dynamic QR to tracking REQUESTED/PAID/CANCELLED/VOIDED states and the requestDt trap that rejects requests even when the entire payload is correct.
Reverse Engineering Spreadsheet Constants into Formulas
A sheet has a criteria table sitting beside the calculations, but no VLOOKUP connects them. People read the table and type values into cells themselves, and mistakes go unnoticed. This article covers separating formula cells from manually entered cells, then reconstructing a single formula that matches all 16 values in a multiplier column.
Making 20,000+ API Calls That Resume Without Leaving Corrupt Files
Generating 26,850 files through an API limited to 20 calls per minute requires three pieces—a system-wide throttle, resuming from what is already on disk, and a separate file validator—because files interrupted by network failures still have the right extension and a nonzero size.
A Cookie Banner That Loads GTM and GA4 Only After Consent
Most cookie banners look good but block nothing, because GTM and GA4 have already loaded from the first line of the page. This article covers a setup that loads the container only after acceptance, puts GA4 inside GTM to prevent double counting, hides AdSense slots initially, and checks that outgoing requests to those services stay at zero.
A Blank Page with No Errors, All Because I Named a Function top
After deployment, the page was blank, the logs had no errors, and node --check found nothing wrong. But the browser stopped the entire script before the first line ran because a function named top collided with window.top. Here are the names to avoid, the script loading order trap, and the Playwright check every project should have.
The App Uses UTC, People Use Thai Time — 7 Hours Off, No Errors
Scheduled for three in the afternoon, published at ten at night. No errors, nothing wrong in the logs, because the app stores UTC while the person entering the time thinks in Thai time. This article traces the issue from an env setting that has no effect to the single line that writes Thai wall-clock time into a column everyone reads as UTC.
php -l Passes, Web Pages Return 500 — A Compile Gate Before Commit
Templates broke twice in one month even though every php -l check passed, because php -l does not understand Blade syntax. This article covers the six-stage gate I put before commit — compiling the views and then linting the compiled files, plus a script that sweeps every GET route through the Kernel.
Auditing prod with real customer data without leaving a single row
The system owner asked me to test the entire system on the live server holding customer data without leaving even a single junk row behind. My approach was to bootstrap Laravel myself and call controllers directly inside a transaction that I rolled back, with a COUNT of every table before and after as evidence.