helper/copy CopyDir was used heavily in tests. It differes from
internal/copydir in a few ways, the main one being that it creates the
dst directory while the internal version expected the dst to exist
(there are other differences, which is why I did not just switch tests
to using internal's CopyDir).
I moved the CopyDir func from helper/copy into command_test.go; I could
also have moved it into internal/copy and named it something like
CreateDirAndCopy so if that seems like a better option please let me
know.
helper/copy/CopyFile was used in a couple of spots so I moved it into
internal, at which point I thought it made more sense to rename the
package copy (instead of copydir).
There's also a `go mod tidy` included.
We missed this on the initial update pass because this was calling
directly into the module package API rather than going through the Meta
methods that we updated for the new config loader.
m.installModules here is the same method that "terraform init" is using
for this purpose, ensuring the two will behave the same way. This changes
the output a little compared to the old installer, but it still includes
the important information about where each module is coming from.
Previously we did plugin discovery in the main package, but as we move
towards versioned plugins we need more information available in order to
resolve plugins, so we move this responsibility into the command package
itself.
For the moment this is just preserving the existing behavior as long as
there are only internal and unversioned plugins present. This is the
final state for provisioners in 0.10, since we don't want to support
versioned provisioners yet. For providers this is just a checkpoint along
the way, since further work is required to apply version constraints from
configuration and support additional plugin search directories.
The automatic plugin discovery behavior is not desirable for tests because
we want to mock the plugins there, so we add a new backdoor for the tests
to use to skip the plugin discovery and just provide their own mock
implementations. Most of this diff is thus noisy rework of the tests to
use this new mechanism.