It's important to preserve the provider address because during the destroy
phase of provider tests we'll use the references in the state to determine
which providers are required, and so without this attempts to override
the provider using the "provider" meta-argument can cause failures at
destroy time when the wrong provider gets selected.
(This is particularly acute in the google-beta provider tests because that
provider is _always_ used with provider = "google-beta" to override the
default behavior of using the normal "google" provider.)
Provider tests often rely on checking values contained within sets, by
directly accessing their flatmapped representation. In order to provider
the test harness with the expected set hashes, the sets must be
generated by the schema.Resource itself.
During the test we now build a fixed map of the providers, which should
only contain schema.Provider instances, and pass them into each
TestStep. The individual schema.Resource instances can then be pulled
from the providers, and used to recreate the state from the cty.Value
returned by the core operations.
We use a shim to convert from the new state model back to the old because
the provider test API is still using the old API throughout. However, the
shim was not preserving the schema version recorded in the new-style state
and so a round-trip through this shim would cause the schema versions to
all revert to zero.
This can cause trouble with the destroy phase of provider tests because
(for API legacy reasons) we round-trip from old state back to new again
before the destroy phase and thus causing the providers to try to upgrade
from state version zero even though the data was already latest, which
can cause errors because state upgrades are generally not idempotent.
James Bardin