Proposal: Simplify `KnownValue` checks for query results

[gdavison]

terraform-plugin-testing version

github.com/hashicorp/terraform-plugin-testing v1.14.0-beta.1

Use cases

When making knownvalue checks on a resource returned by a query, it will be more readable to perform one lookup for the resource and then apply one or more knownvalue checks.

This will especially be the case when looking up a resource by an identity with multiple attributes is supported.

Proposal

Add a querycheck function, e.g. ExpectResourceKnownValues, which will take a list-resource address, a resource lookup mechanism (either by display name or resource identity), and one or more path and knownvalue check pairs.

For example:

querycheck.ExpectResourceKnownValues("example_resource", querycheck.ResourceByIdentity(...), []querycheck.KnownValueCheck{
  querycheck.KnownValue(tfjsonpath.New("attr1"), knownvalue.NotNull()),
  querycheck.KnownValue(tfjsonpath.New("name"), knownvalue.StringExact("example")),
})

It will be an error if the lookup mechanism returns either zero or more than one result.