Testing a business idea without building anything

Help me come up with a minimal test for my business idea, without developing anything.
Suggest five simple ways to validate if there is real demand: [BUSINESS IDEA].
For each method, tell me exactly what I need to create, which signals to look for to know if it’s working, and how to interpret ambiguous results.
Also, give me examples of punchy messages to use in each test to trigger sincere and useful feedback.