Guide offers 12 prompt injection test cases for system prompts

On November 11, 2026, the DEV Community AI section published a guide, originally appearing on Litmiq, that offers 12 single-turn prompt injection test cases designed to be run directly against a system prompt. Two of the 12 are benign controls, so any prompt that falls to a trivial attack can be caught before it reaches users. The guide defines prompt injection as input that pushes a model to behave in ways the developer did not intend. It notes that OWASP ranks this risk first on its Top 10 for LLM applications and draws a distinction between two forms: direct injection, where the user types the attack themselves, and indirect injection, where the attack hides inside content the model reads, such as a web page or a file (OWASP, LLM01:2025 Prompt Injection). The material also cautions against assuming that testing can deliver absolute safety. OWASP states plainly that it is unclear whether fool-proof prevention is even achievable, and the value of testing lies instead in catching degradation early after a prompt is revised or a model is swapped out.