cty's new "refinements" concept allows us to reduce the range of unknown
values from our functions. This initial changeset focuses only on
declaring which functions are guaranteed to return a non-null result,
which is a helpful baseline refinement because it allows "== null" and
"!= null" tests to produce known results even when the given value is
otherwise unknown.
This commit also includes some updates to test results that are now
refined based on cty's own built-in refinement behaviors, just as a
result of us having updated cty in the previous commit.
Previously we were just returning a string representation of the file mode,
which spends more characters on the irrelevant permission bits that it
does on the directory entry type, and is presented in a Unix-centric
format that likely won't be familiar to the user of a Windows system.
Instead, we'll recognize a few specific directory entry types that seem
worth mentioning by name, and then use a generic message for the rest.
The original motivation here was actually to deal with the fact that our
tests for this function were previously not portable due to the error
message leaking system-specific permission detail that are not relevant
to the test. Rather than just directly addressing that portability
problem, I took the opportunity to improve the error messages at the same
time.
However, because of that initial focus there are only actually tests here
for the directory case. A test that tries to test any of these other file
modes would not be portable and in some cases would require superuser
access, so we'll just leave those cases untested for the moment since they
weren't tested before anyway, and so we've not _lost_ any test coverage
here.
Some function errors include values derived from arguments. This commit
is the result of a manual audit of these errors, which resulted in:
- Adding a helper function to redact sensitive values;
- Applying that helper function where errors include values derived from
possibly-sensitive arguments;
- Cleaning up other errors which need not include those values, or were
otherwise incorrect.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
