The fmtcmd tests weren't running before due to the same build tag
problem as #112, so didn't catch the fact that there was an extra
newline being added here, which is now doubled thanks to #112.
Fixing up the build tag reveals failing tests - removing the extra
newline fixes the tests.
The red CI build on Windows is making it harder to process actual bugs -
neither printer or fmt are used in any HC projects currently so
ignoring the tests on AppVeyor/Windows seems reasonable for now. At some
point they need fixing to account for line endings.
This uses the `printer` package to normalise HCL files. It's inspired by
github.com/fatih/hclfmt - but it differs in that it's intended to be more
generic, re-usable, and follow the semantics of `gofmt` or `go fmt`.
I intend to utilise this in Terraform by implementing `terraform fmt`
sub-command which will normalise all files in the current working directory
(like `go fmt ./..`) or contents over STDIN (with `terraform fmt -` that
could be used by editor plugins). So that Terraform users can benefit from
linting without installing another package/binary.
I hope that by placing most of the logic in the HCL package it should be
easy to implement sub-commands in other projects that also use HCL.
Some notes about the implementation:
- the significant difference from `gofmt` is that STDIN/STDOUT are passed in
and errors aren't logged/written directly to STDERR, which gives consumers
(e.g. Terraform) the ability to set appropriate exit codes
- I chose to use inline fixtures instead of files because there were a
number of times where I needed to reference the contents and group them
together with diff output
- it seemed simplest to construct the expected outputs by looping over the
relevant fixtures and building up a string/byte slice, hope it isn't too
confusing to read
- the test failure reporting is kind of rough because the outputs are so
large, but I didn't want to add another diff function
- I chose to have a separate test for sub-directories rather than making it
the default in the fixtures so that I didn't need to add additional logic
to the fixture rendering
- the fixtures are sorted by filename before any of the tests runs so that
they match the order that they are read from disk by `filepath.Walk()`
