You're Shipping Untested Prompts to Production (Here's How to Fix It)

We test our code. We test our APIs. We test our UIs. But most teams ship LLM prompts based on... vibes. "This one seems better" → push to prod → hope for the best. Here's the thing: prompt engineering is experimental science. You need a way to measure, compare, and reproduce results. The Testing Gap When you change a prompt, you need to know: Does it still work? (regression testing) Is it better? (A/B comparison) How much does it cost? (token economics) How fast is it? (latency) Most teams check #1 manually and ignore #2-4 entirely. A Simple Testing Framework Here's the minimum viable prompt testing setup: Step 1: Define Your Prompts as Templates # templates/summarization.yaml prompts: concise: name: "Concise Summary" system: "You are a summarization expert. Be extremely concise." template: "Summarize in 2-3 sentences: {{input}}" detailed: name: "Detailed Summary" system: "You are a thorough analyst." te