My original intention was just to reduce our number of dependencies by
standardizing on a single comparison library, but in the process of doing
so I found various examples of the kinds of problems that caused this
codebase to begin adopting go-cmp instead of go-test/deep in the first
place, which make it easy to accidentally write a false-positive test that
doesn't actually check what the author thinks is being checked:
- deep.Equal silently ignores unexported fields, so comparing two values
that differ only in data in unexported fields succeeds even when it ought
not to.
TestContext2Apply_multiVarComprehensive in package tofu was an excellent
example of this problem: it had various test assertions that were
actually checking absolutely nothing, despite appearing to compare
pairs of cty.Value.
- deep.Equal also silently ignores anything below a certain level of
nesting, and so comparison of deep data structures can appear to succeed
even though they don't actually match.
There were a few examples where that problem had already been found and
fixed by temporarily overriding the package deep global settings, but
with go-cmp the default behavior already visits everything, or panics
if it cannot.
This does mean that in a few cases this needed some more elaborate options
to cmp.Diff to align with the previous behavior, which is a little annoying
but overall I think better to be explicit about what each test is relying
on. Perhaps we can rework these tests to need fewer unusual cmp options
in future, but for this commit I want to keep focused on the smallest
possible changes to remove our dependency on github.com/go-test/deep .
Signed-off-by: Martin Atkins <mart@degeneration.co.uk>
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.
