Idea: Verifier > Show warning 'Empty list/map is risky'

[tienvx]

This idea is related to Optional Attributes

• Single element: Pact doesn't support it to be optional. This is nothing new. If we really want to test optional behavior, on consumer, we need to write 2 tests:
  • Element is null
  • Element match something
• Array of elements/A map: The FAQ said it's not supported, but we can achieve it in many ways:
  • atLeast, atMost, constrainedArrayLike
    • Validate min on consumer, then force setting min >= 1
      • Pact-GO does this
      • But Pact-JS or Pact-PHP doesn't do this (I'm not sure about other languages)
    • There are absolutely nothing stop user from bypassing this validation. User just learn how Json Integration works, then write the syntax by themself (which has min=0, like this Validate min = 0 #304).
    • Validate min=0 in FFI Validate min = 0 #304: @rholshausen doesn't agree with it, and I also don't agree
  • eachKey, eachValue
    • There are nothing we can do to stop provider to return empty list/map
  • matchAll
    • If consumer doesn't add atLeast(), or just add atLeast(0), there are nothing we can do to stop provider to return empty list/map
  • values
    • This matcher is weird (and deprecated in Pact-PHP), so I prefer don't talk about it.

So, it's hard to handle empty list/map on consumer side. How about we do this while verifying provider:

When verifying, if provider return empty list/map, and somehow it match all the rules (describe above), we display a warning like this Empty list/map is very risky. It's suggested to return non-empty list/map to verify its structure