Due to how often the state and plan types are referenced throughout
Terraform, there isn't a great way to switch them out gradually. As a
consequence, this huge commit gets us from the old world to a _compilable_
new world, but still has a large number of known test failures due to
key functionality being stubbed out.
The stubs here are for anything that interacts with providers, since we
now need to do the follow-up work to similarly replace the old
terraform.ResourceProvider interface with its replacement in the new
"providers" package. That work, along with work to fix the remaining
failing tests, will follow in subsequent commits.
The aim here was to replace all references to terraform.State and its
downstream types with states.State, terraform.Plan with plans.Plan,
state.State with statemgr.State, and switch to the new implementations of
the state and plan file formats. However, due to the number of times those
types are used, this also ended up affecting numerous other parts of core
such as terraform.Hook, the backend.Backend interface, and most of the CLI
commands.
Just as with 5861dbf3fc49b19587a31816eb06f511ab861bb4 before, I apologize
in advance to the person who inevitably just found this huge commit while
spelunking through the commit history.
Our existing core tests make extensive use of the string representation
of a state for comparison purposes, because they were written before we
began making use of helper packages like "cmp".
To avoid the need to rewrite all of those tests and potentially break
them, we will instead port that particular rendering as closely as
possible but mark it with a comment sternly warning not to use it for
anything new.
We don't want to use this moving forward for a number of reasons, but
most notably:
- printing out whole before and after state representations makes it
hard to find a subtle difference in outcome when a test fails, while
"cmp" can provide us with a real diff.
- this string serialization is constrained by the capabilities of
Terraform prior to our new state models, and so it does not
comprehensively represent all possibilities in the new world.
- it will probably behave oddly/poorly when given states containing
features that arrived after it was written, even though I made a
best effort here to make it do something reasonable in situations
I thought about.
Martin Atkins