Placeholder (or similar concept) with generic matching

Sometimes, I don’t know the exact value my API would return, but I know that it has to return a value, and maybe I know that the value has to have a specific shape (e.g. an UUID or a Date).

Currently, I can use body.path("id").isPresent to assert that a value is there at all. This is somewhat fine, but doesn’t have a nice reading flow, e.g.:

And assert body.whiteListing.is(
"""
{
  "firstName": "Foo",
  "lastName": "Bar",
  "isAwesome": true
}
""")
And assert body.path("id").isPresent

The reading flow is better if the "id" presence is checked within the body-assertion.

And assert body.whiteListing.is(
"""
{
  "id": <is-present>,
  "firstName": "Foo",
  "lastName": "Bar",
  "isAwesome": true
}
""")

It would be even better if we can define matchers for the shape of the fields, e.g.:

And assert body.whiteListing.is(
"""
{
  "id": "<any-uuid>",
  "firstName": "Foo",
  "lastName": "Bar",
  "isAwesome": <any-boolean>,
  "createdAt": "<any-iso-date>"
}
""")

I used the <> syntax from placeholders in the examples. It would also be completely valid to introduce another syntax for it, as it’s a different concept (e.g. []).

[agourlay]

Looks really good, thank you for the input! I can definitely see how this could improve the user experience.

However it does require a non-trivial modification of the current model so no promises 😄

[agourlay]

I have done the predicate change, the code is much cleaner. https://github.com/agourlay/cornichon/commit/9c9733e5f7d58e2576b1f3d607ec81b0a02e4812

I also added a description field to help our dear users :bowtie: