The error message for `plancheck.ExpectUnknownValue` is misleading when value is known

[gdavison]

terraform-plugin-testing version

github.com/hashicorp/terraform-plugin-testing v1.11.0

Relevant provider source code

plancheck.ExpectUnknownValue(resourceName, tfjsonpath.New(names.AttrRule).AtSliceIndex(0).AtMapKey("prefix"))

Expected Behavior

The test failure message should indicate something like

Expected unknown value for 'rule[0].prefix', but had known value "prefix".

Actual Behavior

The test failure message is

path not found: specified key prefix not found in map at rule.0.prefix

Steps to Reproduce

1. Run an acceptance test with a plancheck.ExpectUnknownValue where the plan returns a known value

[austinvalle]

Agreed! Will look into this before our next release 👍🏻