The most common usage usage will be enabling the `-write` and `-list`
options so that files are updated in place and a list of any modified files
is printed. This matches the default behaviour of `go fmt` (not `gofmt`). So
enable these options by default.
This does mean that you will have to explicitly disable these if you want to
generate valid patches, e.g. `terraform fmt -diff -write=false -list=false`
This uses the `fmtcmd` package which has recently been merged into HCL. Per
the usage text, this rewrites Terraform config files to their canonical
formatting and style.
Some notes about the implementation for this initial commit:
- all of the fmtcmd options are exposed as CLI flags
- it operates on all files that have a `.tf` suffix
- it currently only operates on the working directory and doesn't accept a
directory argument, but I'll extend this in subsequent commits
- output is proxied through `cli.UiWriter` so that we write in the same way
as other commands and we can capture the output during tests
- the test uses a very simple fixture just to ensure that it is working
correctly end-to-end; the fmtcmd package has more exhaustive tests
- we have to write the fixture to a file in a temporary directory because it
will be modified and for this reason it was easier to define the fixture
contents as a raw string
Dan Carley