ale/test/command_callback
Keith Maxwell 88fa0b9294 Add a terraform linter
This linter uses the check functionality built into terraform. ALE
already has a fixer using `terraform fmt` but this doesn't provide error
messages. ALE already has a linter using `tflint` but this requires an
extra application to be installed.

For example this linter will give a warning that ! is an illegal
character in the line below:

    variable "example" !{}

This linter runs the buffer through the command below and parses the
output:

    terraform fmt -no-color -check=true -

This commit includes a basic implementation, documentation and tests.
The only option is to control which executable is run.

Tested with:

    $ terraform -version
    Terraform v0.11.13
2019-05-23 15:49:02 +01:00
..
2018-12-01 15:05:18 +09:00
2018-09-07 13:16:22 -04:00
2017-06-28 15:27:02 +01:00
2018-12-10 14:02:32 -07:00
2018-12-11 23:44:06 +09:00
2018-06-23 22:59:13 +05:30